Initial Radiotherapy Research Articles

How Does the Interval Between Completion of Adjuvant Chemotherapy and Initiation of Radiotherapy Impact Clinical Outcomes in Operable Breast Cancer Patients?

PurposeThe aim of this study was to evaluate the impact of time to radiotherapy (TTR) after completion of chemotherapy (CT), and TTR after surgery, in breast cancer (BC) patients.Patients and MethodsContinuous breast cancer patients treated with surgery and CT followed by radiotherapy (RT) from 2009 through 2015 were retrospectively reviewed. Patients were categorized into four groups with respect to TTR after CT, i.e. <4, 4–8, 8–12, and >12 weeks, and TTR after surgery, i.e. <147, 147–180, 180–202, and >202 days. The Cox proportional hazards model was used to identify the independent effect of TTRs.ResultsOverall, 989 patients were enrolled. Patients with a TTR of >12 weeks after CT showed significantly worse breast cancer-specific survival (BCSS) and overall survival (OS) compared with those who had a TTR of <4 weeks (BCSS: hazard ratio [HR] 0.28, 95% confidence interval [CI] 0.1–0.76; OS: HR 0.33, 95% CI 0.13–0.88), 4–8 weeks (BCSS: HR 0.23, 95% CI 0.08–0.66; OS: HR 0.29, 95% CI 0.11–0.8), and 8–12 weeks (BCSS: HR 0.22, 95% CI 0.05–0.96; OS: HR 0.23, 95% CI 0.06–0.99). TTR after surgery showed no significant association with survival outcomes in the entire cohort, except in patients with hormone receptor (HR)-positive disease and those receiving mastectomy. In HR-positive tumors, a TTR after CT of >12 weeks remained an independent predictor for adverse BCSS and OS.ConclusionInitiation of RT beyond 12 weeks after CT might compromise survival outcomes. Efforts should be made to avoid delaying RT, especially after completion of CT and in patients with HR-positive tumors, positive lymph nodes, and those receiving mastectomy.

Salvage Treatment for Recurrent IDH-mutant Diffuse Gliomas after Radiation Therapy

Optimal management of patients diagnosed with recurrent IDH-mutant gliomas (IMGs) who relapse after prior radiation therapy (RT) is not well defined. This study evaluates the patterns of care and outcomes of our institutional experience with recurrent IMGs. Recurrent IMG patients including IDH-mutant astrocytomas (AC) and 1p/19q codeleted oligodendrogliomas (OD) from 1997-2019 were retrospectively reviewed at our institution. Recurrence was defined as progressive disease after initial RT with/without chemotherapy. IDH-mutation was confirmed using either immunohistochemistry or sequencing on either initial or recurrent tissue. Overall survival (OS) was calculated from the date of first recurrence and compared using Kaplan-Meier analysis. From 1997-2019, 100 patients with IMGs received salvage treatment after recurrence (49% OD, 51% AC). Tumor grade at recurrence was classified as: II (29%), III (55%) or IV (16%). First-line salvage therapies included: surgery alone (9%), chemotherapy alone (70%), RT alone (4%), and chemoradiotherapy (17%). Across all recurrences, 94% received chemotherapy (90% for OD and 98% for AC); 67% had surgery (71% for OD and 63% for AC); 40% had re-irradiation (41% for OD and 39% for AC). The median dose of re-irradiation was 36 Gy or GyRBE, and the most common technique was proton beam therapy (30%). After a median follow up of 21 months (range 1 – 256), OS was 63% at 2 years and 47% at 5 years. Patients with OD had significantly better OS than patients with AC: 74% vs 50% at 2 years, 56% vs 38% at 5 years, respectively, p=0.02. Among the OD patients, those treated with re-irradiation had higher but not statistically different OS than chemotherapy alone: 84% vs 65% at 2 years, respectively, p=0.62; a similar trend was also observed for the AC patients: 70% vs 37% at 2 years, respectively, p=0.31. Although chemotherapy was the most common salvage treatment for recurrent IDH-mutant OD and AC, local therapies such as surgery and re-irradiation were frequently used. The incorporation of re-irradiation with chemotherapy may warrant further investigation.

Does Age Impact Outcomes of Oropharyngeal squamous cell carcinoma?

It is well-established that human papilloma virus (HPV) positive (+ve) oropharyngeal (OP) squamous cell carcinoma (SCC) carries a better overall prognosis than HPV negative (-ve) tumors. We sought to investigate the impact of age upon survival endpoints for HPV +ve and -ve OP SCC as well as the differences in acute radiotherapy (RT) toxicity. We included all OP SCC cases treated definitively between 2010-2017. All cases underwent either surgery ± adjuvant RT; or definitive RT ± chemotherapy according to the multidisciplinary tumor board decision. After determining p16 status we dichotomized each HPV group by age at diagnosis into old (> or = 65 years) and young (<65 years) sub-groups. Patients' demographics, clinico-pathological data and treatment modalities were compared across age groups for both HPV sub-types. Log-rank test and Kaplan-Meier curves were utilized to measure effect of age on overall (OS), local recurrence free (LRFS) and distant metastases free (DMFS) survival for HPV +ve and -ve. For patients receiving RT we compared weight loss, feeding tube insertion, treatment breaks and hospitalization during RT as parameters for acute toxicity across age groups. We identified 217 OP SCC who fit our inclusion criteria. Seventy percent were HPV+ve, males were 82%, mean age at diagnosis was 61 years, 75% were white, 67% were ever smokers and 54% were frequent/heavy alcohol drinkers. According to AJCC 7th edition, Stages III and IVA formed 87%; however, these were regrouped as stage I (51%) and stage IVA (62%) as prevalent stages for HPV+ve and -ve respectively as per AJCC 8th version. Definitive CRT was utilized in 58% and surgery ± adjuvant therapy in 31% of the study cohort. For HPV+ve sub-group, 31% were old (n=47); whereas they constituted 40% (n=27) of HPV-ve cases. Clinicopathological and treatment characteristics were generally equivalent among age groups except that HPV +ve younger patients had more adequate surgical margins (≥5mm) (78% vs 36%; p=0.03) than old; and HPV-ve old cases had a trend towards more utilization of concomitant cetuximab (30% vs 13%; p=0.09) than younger ones. All endpoints were not significantly different between old vs young HPV+ve cases with 2-year OS and LRFS of (64% vs 59%; p=0.41 and 88% vs 87%; p=0.98 for both respectively). Similar outcomes were observed between study age groups for HPV-ve cases (p>0.05 for all endpoints). Hospitalization during RT was more frequent in old patients (44% vs 28%; p=0.03). Median weight loss during RT was 9.5% (0-22%) vs 9.3% (0-17%) for old vs young (p=0.35) and RT breaks were also non-significant (39% vs 27%, p=0.8). Feeding tubes were inserted after RT initiation in 41% of old and 36% in young (p=0.5). Older patients with OP SCC have equivalent outcomes compared to younger ones irrespective of HPV status. Optimal treatments must be offered following standard of care as determined by a multi-disciplinary group of providers.

The Impact of 18F-DCFPyL PET-CT Imaging on Initial Staging, Radiation, and Systemic Therapy Treatment Recommendations for Veterans With Aggressive Prostate Cancer

PurposeOur purpose was to study the effect of 2-(3-{1-carboxy-5-[(6-[18F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (18F-DCFPyL) positron emission tomography (PET)-computed tomography (CT) on staging/treatment recommendations of previously untreated prostate cancer. We report here results of a prospective single center single arm imaging trial within Veterans Affairs (Greater Los Angeles): the frequency of patients upstaged to M1 disease (primary endpoint) and the frequency of patients with change in treatment recommendations (secondary endpoint). This is the first report of prostate-specific membrane antigen PET-CT exclusive to U.S. veterans. Methods and MaterialsVeterans with Gleason ≥4 + 3, clinical stage ≥T2c, or prostate-specific antigen >10 ng/mL were eligible. Patients underwent conventional imaging (99mTc-methyl diphosphonate bone scan or 18F-NaF PET-CT; and pelvic CT or pelvic magnetic resonance imaging) in addition to 18F-DCFPyL PET-CT. The effect of 18F-DCFPyL PET-CT on treatment change was determined by applying prespecified treatment recommendations based on National Comprehensive Cancer Network guidelines and modern clinical practice. ResultsOne hundred patients underwent 18F-DCFPyL PET-CT. Nineteen out of 84 (23%) patients initially thought to be nonmetastatic were upstaged to M1; 8/16 (50%) patients initially thought to have M1 disease were downstaged to M0. In total, 39/100 (39%) had a change in prespecified treatment recommendations, including change of radiation therapy volume/dose in 39/100 (39%) and starting abiraterone in 22/100 (22%). ConclusionsIncorporation of 18F-DCFPyL PET-CT into the initial conventional imaging workup for prostate cancer can substantially affect staging/treatment recommendations.

Circulating Cell-Free DNA Correlates with Body Integral Dose and Radiation Modality in Prostate Cancer.

PurposeThe RadTox assay measures circulating cell-free DNA released in response to radiotherapy (RT)-induced tissue damage. The primary objectives for this clinical trial were to determine whether cell-free DNA numbers measured by the RadTox assay are (1) correlated with body integral dose, (2) lower with proton RT compared with photon RT, and (3) higher with larger prostate cancer RT fields.Patients and MethodsPatients planned to receive proton or photon RT for nonmetastatic prostate cancer in the setting of an intact prostate or postprostatectomy were eligible for the trial. Plasma was collected pre-RT and at 5 additional daily collection points beginning 24 hours after the initiation of RT. Data from 54 evaluable patients were analyzed to examine any correlations among RadTox scores with body-integral dose, RT modality (photon versus proton), and RT field size (prostate or prostate bed versus whole pelvis).ResultsBody integral dose was significantly associated with the peak post-RT RadTox score (P = .04). Patients who received photon RT had a significant increase in peak post-RT RadTox score (P = .04), average post-RT RadTox score (P = .04), and day-2 RadTox score (all minus the pre-RT values for each patient) as compared with patients who received proton RT. Field size was not significantly associated with RadTox score.ConclusionRadTox is correlated with body integral dose and correctly predicts which patients receive proton versus photon RT. Data collection remains ongoing for patient-reported RT toxicity outcomes to determine whether RadTox scores are correlated with toxicity.

Outcomes after reirradiation of spinal metastasis with stereotactic body radiation therapy (SBRT): a retrospective single institutional study.

ABSTRACTThis study was aimed at assessing the feasibility and toxicity of using stereotactic body radiation therapy (SBRT) for reirradiation of spinal metastatic tumors. We conducted a retrospective review, from our institutional database, of the data of patients who received reirradiation, with overlap of some prescribed isodose lines to the vertebra from the initial radiation therapy, between 2007 and 2019. We identified 40 patients with spinal metastatic tumors, of whom 2 had 2 metastatic vertebral lesions each, totaling up to 42 target lesions. The median dose to spinal cord at the initial radiation therapy was 30 Gy. SBRT based on the intensity-modulated radiation therapy (IMRT) technique was used for reirradiation to spare the spinal cord. All patients received a prescription dose of 25 Gy in 5 fractions to the planning target volume (PTV). Among the 40 cases who had pain, pain relief was obtained in 24 (60%) after reirradiation. Neurologic improvement was obtained in 8 of 15 cases (53%). The adverse events were evaluated using the Common Terminology Criteria for Adverse Events Version 5.0. Reirradiation was well-tolerated, with only 2 patients experiencing adverse events ≥grade 2 in severity, including 1 patient with grade 3 pain, and another patient with grade 3 spinal fracture. None of the patients developed radiation myelopathy. Our data demonstrated that reirradiation of spinal metastasis using SBRT provided effective pain relief and neurologic improvement, with minimal toxicity.

Treatment Outcomes for Primary Retromolar Trigone Carcinoma: A Single Institution Experience.

Retromolar trigone (RMT) is a rare location for oral cavity cancers. RMT cancers are aggressive malignancies that mostly present at an advanced stage. In this study, we aimed to evaluate treatment outcomes in patients who underwent initial radical surgical resection and postoperative radiotherapy or chemoradiotherapy with a diagnosis of primary RMT squamous cell carcinoma in our institution. The study included 20 primary RMT tumor patients out of 191 oral cavity cancer cases treated from January 2010 through December 2019. We retrospectively analyzed treatment details, histopathology reports, postoperative clinical course and survival outcomes. The mean age at presentation was 59.4 years. Eighty percent of all patients were either stage 3 or stage 4. We performed mandibular resection in 14 patients (70%) and partial maxillectomy in eight patients (40%). Nineteen patients (95%) underwent unilateral neck dissection. The incidence of metastatic cervical lymph node was 13/20 (65%). Overall survival (OS) and disease-free survival (DFS) rates during follow-up (mean 26.3 months) were 60% and 75%, respectively. There was statistical significance between presence of multilevel metastatic lymph nodes and OS (p=0.013). DFS and OS of early stage and advanced stage groups were 100% vs 75% and 100% vs 50%, respectively, with no statistical significance (p=0.189 and p=0.084). The survival of advanced stage RMT cancer is poor despite appropriate treatment. Bone involvement that necessitates resection is common due to the proximity of the tumor to the mandible and the maxilla. Multilevel positive cervical lymph nodes and advanced stage are poor prognostic factors.

The Management of rNPC: Salvage Surgery vs. Re-irradiation.

Treatment failure, in the form of either persistence or local recurrence, occurs in 10 to 30% of nasopharyngeal carcinoma patients after initial radiotherapy (RT). Early detection of persistent or recurrent disease aids in the recognition of tumors that can be candidates for salvage nasophayngectomy or re-irradiation. There is no consensus till now on the indications or selection of the above two salvage treatment. In recent years, there has been a paradigm shift from open to endoscopic approach for nasopharyngectomy, which carries nearly no complications. For salvage re-irradiation, intensity-modulated radiotherapy (IMRT) is the most commonly indicated modality. Compared to IMRT, salvage endoscopic nasopharyngectomy may be more beneficial in terms of prolonging survival, improving quality of life, and minimizing treatment-related complications and medical costs in a selected subset of recurrent nasopharyngeal carcinoma (rNPC) patients. Salvage nasopharyngectomy should be the mainstay of treatment for rNPC.

Hyaluronic acid spacer in focal prostate reirradiation: A single centre experience

PurposeThe optimal management of locally recurrent prostate cancer after curative radiotherapy is still unknown. In this study, we evaluated the preliminary results of reirradiation using stereotactic body radiotherapy for locally recurrent prostate cancer after initial definitive local radiotherapy. Materials and methodsBetween April 2016 and February 2019, 11 patients with recurrent disease at the previously irradiated prostate were treated. Local recurrence was detected by radiological with or without functional imaging modalities including prostate multiparametric/pelvic MRI or positron-emission tomography–computerised tomography with (68Ga)-labelled prostate-specific membrane antigen performed after rising prostate specific antigen serum level during follow-up. All patients received stereotactic body radiotherapy to the recurrent nodule to a total dose of 30Gy in five fractions. Hyaluronic acid spacer was injected between prostate and rectum in seven patients to decrease the rectal dose. Acute toxicity was evaluated by using Common Terminology Criteria for Adverse Events version 4.0, and late toxicity was evaluated by using Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer late radiation morbidity scoring schema. ResultsAt the diagnosis, the median age was 64 years, and the mean prostate specific antigen serum concentration was 17.7ng/mL. The median interval time between local recurrence and initial definitive radiotherapy was 63 months. Mean prostate specific antigen concentration nadir value during follow-up was 0.43ng/mL. With a median follow up of 19 months, three patients developed either local or distant relapse. One patient had grade 3 acute rectal toxicity, and one patient had grade 2 late urinary toxicity. We did not observe any acute or late toxicity due to hyaluronic acid spacer injection. ConclusionReirradiation after local recurrence following initial definitive radiotherapy together with hyaluronic acid spacer use seems to be effective and safe.

Reirradiation of High-Grade Gliomas: A Retrospective Analysis of 198 Patients Based on the Charité Data Set

PurposeThere is no standard of care for recurrent high-grade glioma. Treatment strategies include reresection, reirradiation, systemic agents, intratumoral thermotherapy using magnetic iron-oxide nanoparticles (“nanotherapy”), and tumor treating fields. Only a small number of patients are eligible for reresection, and because many patients receive a full course of radiation therapy, there is fear of reirradiation-induced morbidity. Modern radiation techniques have resulted in greater acceptance of reirradiation. In this work we retrospectively analyzed patients who had undergone reirradiation of high-grade glioma at Charité Universitätsmedizin Berlin. Methods and MaterialsAll patients treated with reirradiation for recurrent high-grade glioma in our department from January 1997 to February 2014 were analyzed in this study. In total, 198 patients were included. The primary endpoint was overall survival after recurrence. ResultsOne hundred ninety-eight patients were identified. Median time from first radiation therapy to reirradiation was 14 months. Median follow-up from the first day of reirradiation to last contact or death was 7 months. Median overall survival after relapse was 7 months for the overall cohort. For glioblastoma, median overall survival after relapse was 6 months and for grade 3 gliomas 14 months. Treatment was generally well tolerated. Common Terminology Criteria for Adverse Events grade 3 toxicity was observed in 5.1% patients and grade 4 toxicity in 2.5%. No patient developed grade 5 toxicity. The likelihood of developing severe toxicity (Common Terminology Criteria for Adverse Events grade 3 or 4) was not significantly higher in the group of patients who received reirradiation in the first 14 months after initial radiation therapy. Patients who received a higher biologically effective dose to the tumor also did not have a significantly higher rate of severe acute toxicity. ConclusionsThe prognosis of recurrent high-grade glioma remains dismal. Reirradiation is often tolerable even after early recurrence (<14 months) and with higher doses (eg, 49.4 Gy/3.8 Gy) in selected patients.

Abstract B023: Racial-ethnic disparities in the receipt of initial, cure-intended treatment for localized prostate cancer, SEER Medicare, 2004-2013

Abstract Purpose: We sought to determine if there were racial/ethnic disparities in the receipt of initial, cure-intended treatment for localized prostate cancer. Methods: We analyzed prostate cancer cases reported in 2004-2013 to Surveillance, Epidemiology and End Results (SEER) cancer registries, linked with Medicare claims from 2003-2014. We focused on cases that were fee-for-service with continuous Part A and B Medicare from 12 months before first diagnosis to 6 months after diagnosis, and that had American Joint Committee on Cancer 6th Edition tumor extent T1 or T2 without metastatic disease. We used SEER race/ethnicity to categorize cases as non-Hispanic whites; non-Hispanic blacks; non-Hispanic Asian or Pacific Islanders; Hispanics of any race; and Other/Unknown. We defined initial treatment to include 1 month before to 6 months after first diagnosis; cure-intended radical prostatectomy to include radical prostatectomy with or without radiation therapy; cure-intended radiation therapy to include radiation therapy without a radical prostatectomy; and noncurative treatment to include other initial treatment or no treatment. We used multivariable logistic regression to calculate adjusted odds ratios (OR) and 95% confidence intervals (CI) for receipt of each category of initial treatment, compared with the remaining cases, and adjusting for race/ethnicity; life expectancy from the man's age at diagnosis; pretreatment prostate cancer disease recurrence risk category; Charlson comorbidity score; year of diagnosis; SEER registry region, census tract poverty; and metropolitan or nonmetropolitan county location. Results: Our final study cohort included a total of 125,072 men, with 95,763 non-Hispanic white, 13,616 non-Hispanic black, 4,658 non-Hispanic Asian or Pacific Islanders, 7,933 Hispanic any race, and 3,102 in the Other/Unknown category. After adjustment for multiple variables, non-Hispanic blacks were less likely than non-Hispanic whites to receive initial radical prostatectomy (with or without radiation therapy) (OR, 0.57; 95% CI, 0.53-0.61) or initial radiation therapy without radical prostatectomy (OR, 0.85; 95% CI, 0.82-0.88), and more likely to receive noncurative treatment (OR, 1.51; 95% CI, 1.45-1.57). Non-Hispanic Asian or Pacific Islanders were more likely than non-Hispanic whites to receive initial radiation therapy without radical prostatectomy (OR, 1.23; 95% CI, 1.16-1.31), and less likely to receive noncurative treatment (OR, 0.84; 95% CI, 0.78-0.89). The adjusted odds ratios for curative and noncurative initial treatment received by Hispanics of any race were similar to those for non-Hispanic whites. Conclusion: Compared with non-Hispanic whites, non-Hispanic black men were less likely to receive curative and more likely to receive noncurative initial treatment for localized prostate cancer during 2004-2013. Citation Format: Thomas B. Richards, David G. Stinchcomb, Timothy S. McNeel, Wilhelmina Ross, Diane Ng. Racial-ethnic disparities in the receipt of initial, cure-intended treatment for localized prostate cancer, SEER Medicare, 2004-2013 [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr B023.

Role of radiotherapy and dose-densification of R-CHOP in primary mediastinal B-cell lymphoma: A subgroup analysis of the unfolder trial of the German Lymphoma Alliance (GLA).

8041 Background: Primary mediastinal B-cell lymphoma (PMBCL) is a distinct entity of aggressive lymphoma, which typically presents in young patients (pts) with a bulky mediastinal mass. Therapy is based on R-CHOP or similar regimens, but the role of treatment intensification and consolidative radiotherapy (RT) is controversial, because data from randomized trials are rare. Methods: The UNFOLDER trial included 18-60 year-old pts (aaIPI = 0 with Bulk [≥7.5 cm] or aaIPI = 1) qualifying for radiotherapy to Bulk or extralymphatic involvement (E). Pts were randomized in a 2 x 2 factorial design to 6xR-CHOP-14 or 6x-R-CHOP-21 without RT or with RT (39.6 Gy) to Bulk and E. Primary endpoint was event-free survival (EFS), secondary endpoints were progression-free (PFS) and overall survival (OS). Response was evaluated by the Internat Standardized Response Criteria, Cheson 1999. Results: 131 PMBCLs were included with a median age of 34 years, 54% were female, 79% had elevated LDH &gt; UNV and 24% had E. 82 pts (R-CHOP-21: 43; R-CHOP-14: 39) were assigned to RT and 49 (R-CHOP-21: 27, R-CHOP-14: 22) to no-RT. 96% (79/82) received RT per protocol and 5 pts in the no-RT arm received unplanned RT (4 after PR and 1 after CR/CRu). Response RT vs no-RT were CR/Cru 94% vs 84%, PR 2% vs 10%, PD 2% vs 4%. 3-year EFS was superior in pts assigned to RT (94% vs. 78%; p = 0.007), mostly due to events caused by initiation of RT (n = 5) in the no-RT arm. In an as treated analysis the difference between the RT and the no-RT arm was not significant (p = 0.136). Regarding PFS and OS no difference between the RT vs no-RT arm was detected (PFS: 95% (95% CI: 90-100) vs 90% (95% CI: 81-98), p = 0.253; OS: 98% (95% CI: 94-100) vs 96% (95% CI: 90-100), p = 0.636). Dose-densification of R-CHOP-21 by R-CHOP-14 did not improve EFS, PFS nor OS. Only 4 pts died. Conclusions: To our knowledge, this is the largest series of PMBCLs so far, which have been treated in a prospective, randomized trial in the rituximab era. The results reveal no differences between R-CHOP-14 vs R-CHOP-21. Pts assigned to RT had a superior EFS mostly due to a higher PR rate in the no-RT arm triggering RT, with no differences in PFS and OS. The results suggest a benefit of RT only for pts, who are responding to R-CHOP with PR. Testing RT in PET-positive residual tumors in a randomized trial can solve the question, while RT in PET-negative pts is studied in the ongoing randomized IELSG 37 trial. Our results indicate a very favorable 3-year OS of 96% in PMBCL pts treated with R-CHOP. Supported by Deutsche Krebshilfe, Amgen and Roche. Clinical trial information: NCT00278408 .

Definitive re-irradiation of locally recurrent esophageal cancer after trimodality therapy in patients with a poor performance status.

There are few treatment guidelines for locally recurrent esophageal cancer after trimodality treatment (pre-operative chemoradiation followed by surgery) in patients with a poor performance status. The purpose of this single institutional, retrospective study was to evaluate the clinical outcomes and toxicities of definitive-intent re-irradiation for patients with recurrent esophageal cancer with a poor performance status [ECOG (Eastern Cooperative Oncology Group) ≥2]. Seven patients were identified with a median age of 74 years (range, 61-81 years). Four patients were ECOG 2 and three patients were ECOG 3. The median follow-up time after re-irradiation was 49 months. The median interval between initial radiotherapy and re-treatment was 32 months. Six patients received concurrent chemotherapy [carboplatin + paclitaxel in three patients; folinic acid, fluorouracil, oxaliplatin (FOLFOX) + 5-fluorouracil in one patient; FOLFOX in one patient, and capecitabine in one patient]. At the last follow-up, the six patients who underwent concurrent chemotherapy had stable disease (86%), while the one who did not receive chemotherapy progressed (14%). Two patients developed metastases. Three patients developed acute (<6 months) grade 4 toxicities (dysphagia, anemia, esophagitis). There were no early deaths attributable to treatment. Late toxicities (>6 months) were limited to grades 1 and 2 dysphagia and pneumonitis in four patients. In conclusion, definitive re-irradiation of recurrent esophageal cancer in patients with a poor performance status appears to be safe with acceptable acute toxicity and late complications. It also appears to result in durable local control when combined with chemotherapy, albeit with a small number of patients and limited follow-up.

MON-308 Pituitary Magnetic Resonance Imaging in the Postoperative Follow-Up of Patients with Acromegaly, Less Is More!

Background Patients (pts) with acromegaly (A) require long term follow up, as up to 15% will develop recurrence. Current guidelines for MRI surveillance recommend 12 week post-operative (postop) imaging for all pts and yearly if on pegvisomant (PEG). Many pts with residual tumor postop undergo repetitive imaging even when controlled with pituitary (PIT) directed therapies. However, gadolinium retention and healthcare costs are of increased concern. Aim Assess tumor growth postop and necessity of serial MRI in medically treated A pts. Methods Retrospective, IRB-approved, data analysis of pathology-proven A pts. Included were pts with at least 1 MRI at ≥1 year postop. Initial tumor size, invasion status, pathology, postop remission, MRIs, radiation and medical therapy data were collected. Biochemical (biochem) remission = normal IGF-1 and GH <1 at 3 mo postop. For pts with radiation, data was only collected up to radiation. Stats: t-test, chi-square. Results 83 pts were included; mean age 46±16 years, 45% female, mean follow up 7.9±5.3 years. 55 pts were on PIT-directed therapy (50 on somatostatin receptor ligands (SRL) alone, 1 on cabergoline (Cab) alone, 4 on SRL/Cab), 12 on PEG > 1 year (9 on PEG alone.) 11/83 (13.25%) had tumor growth at median 3.5 years (range 1-11). Tumors that grew were larger at diagnosis (25.21±10.93 mm vs 17.45±8.37 mm, p=0.004), had larger residuals postop (23.83±5.0 mm vs 11.86±7.47 mm, p=0.0003), and tended to be invasive (77.78% (7/9) vs 53.03% (35/66), p=NS). 7/11 were sparsely granulated and 4 mixed GH-PRL. Of 11 that grew, 8 had postop residual tumor, 3 in remission, 4 with discrepant IGF-1/GH, 2 uncontrolled and 2 with no data at 3 months postop. At the time of growth, 9/11 pts were untreated (6 had active A, 1 with discrepant IGF-1/GH and 2 with no IGF-1/GH data), 1 was controlled on pasireotide and one in biochem remission. Only 1/50 (2%) pts on pasireotide had growth and no pts on PEG >1 year. Discussion 86.75% of pts with A did not have tumor growth after surgery. Only one pt on PIT-targeted medications and none on PEG experienced tumor growth. Almost all pts who had growth had large invasive adenomas, majority were sparsely granulated, residual tumor postop, were biochemically uncontrolled and not on medication at the time of growth. A previous metanalysis of SRLs in A showed that tumor increase occurs in 1.4% (follow up 3-36 months). In our study pt follow up was longer and 1.82% (1/55) of pts who were on SRL/Cab had growth. Conclusion We recommend less frequent MRI monitoring for pts treated with PIT-targeted medications. Conversely, pts with residual adenoma not on medical therapy should be closely monitored biochemically and by serial MRIs. Further studies are needed to identify appropriate imaging interval for pts on medications and based on characteristics of aggression (such as sparsely granulated, large residual tumors, lack of biochemical control despite medications).

SUN-279 A Rare Case of Atypical Rhaboid Teratoid Tumour with Germinoma Differentiation in a 59 Year Old Woman

Atypical teratoid/rhabdoid tumours (ATRT) are a rare class of central nervous system malignant tumours which are comprised of elements of ectoderm and mesoderm germ-cell layers, but exhibit microscopic similarity to skeletal muscle. These tumours are more commonly seen in pediatric patients, with few case reports recently describing adult patients with this condition, in particular middle-aged women.1–3 We present the case of a previously healthy 59-year-old woman who was found incidentally to have a pituitary mass on CT head, with retrospective symptoms of headaches, polyuria, polydipsia, diplopia, and low blood pressure. At presentation, she was found biochemically to have pan-hypopituitarism with a left cranial nerve six deficit, with an MRI depicting a 19.5 x 22 x 11 mm suprasellar mass extending into the infundibulum and hypothalamus, with displacement of the optic chiasm; repeat imaging ruled out apoplexy. She was started on supplemental levothyroxine and hydrocortisone replacement therapy, and sent for urgent transsphenoidal resection, which was complicated afterwards by hypernatremia from diabetes insipidus. Preliminary reports were suggestive of germinoma given the diffuse presence of Oct 3/4 and C-kit, with a proliferation index of 99%; further cytology of lumbar puncture revealed no malignant cells. However, upon further pathological analysis, her tumour demonstrated loss of INI-1 expression, which is diagnostic of ATRT. Given the mixed features on immunohistochemistry, the final diagnosis was concluded as an atypical teratoid/rhabdoid tumour of the sella turcica with germinoma differentiation. A multi-disciplinary approach consisted of initial radiotherapy, with chemotherapy targeted towards a germinoma-type tumour, and pituitary hormone replacement including treatment for central diabetes insipidus. This represents a unique case of a rare tumour with germinoma differentiation in an older patient that has not been previously reported.

Efficacy of stereotactic radiosurgery for radiation-induced meningiomas.

Stereotactic radiosurgery is an established treatment option for sporadic meningiomas, though limited data exists for radiation-induced lesions. Patients treated with cobalt-60 radiosurgery between October 2005 and December 2018 in an institutional registry were reviewed. Single fraction treatments were prescribed to the 50% isodose line. Lesions were deemed to be radiation-induced according to standard criteria previously established by Cahan et al. RESULTS: A total of 37 patients with 72 lesions were analysed. Median follow up per patient was 44months (range, 1.4-150.7months). Median age at initial radiotherapy was 5years (4months-48years), and at radiosurgery was 38years. Of the 72 lesions, 62 were grade 1 (n = 4) or radiologically-diagnosed (n = 58), six were grade 2 and four were grade 3. Median lesion volume was 2.13cc (0.04-13.8cc), while the median radiosurgery margin dose was 13Gy. Local control, on a per lesion basis, was 88.6% at 5years (95% confidence interval [CI] 72.3-95.6). For grade 1 or radiologically-diagnosed lesions, local control was 96.6% at 5years (95% CI 77.9-99.5), whereas those with grade 2 or higher lesions had a local control of 40% at 5years (95% CI 5.2-75.3, p = 0.005). Radiologic oedema developed in 17 lesions (23.6%) and was symptomatic in 12 patients (16.7%). Doses above 12Gy were not associated with local control probability (p = 0.292). Radiosurgery is an effective treatment option for grade 1 or radiologically-diagnosed radiation-induced meningiomas, with 12Gy appearing to be a sufficient dose.

Efforts to Reduce the Impact of Coronavirus Disease 2019 Outbreak on Radiation Oncology in Taiwan

Efforts to Reduce the Impact of Coronavirus Disease 2019 Outbreak on Radiation Oncology in Taiwan

Effect of early radiotherapy initiation and high-dose chemotherapy on the prognosis of pediatric atypical teratoid rhabdoid tumors in different age groups

The optimal treatment strategy for pediatric atypical teratoid rhabdoid tumor (ATRT) is inconclusive. This study evaluated the prognostic value of early radiotherapy (RT) and high-dose chemotherapy with autologous stem cell rescue (HDC/ASCR) in pediatric ATRT. This pooled analysis included ATRT patients treated at our institution and from other studies who were identified by a search of the PubMed electronic database. The effect of patient demographics and treatment profiles on progression-free survival (PFS) and overall survival (OS) were analyzed using Cox regression. Overall, 34 patients from our institution and 436 patients from 35 published studies were included. In multivariable analysis, patients with gross total resection (GTR), early RT (time to RT interval < 2months), and HDC/ASCR had both better PFS [hazard ratio (HR) 0.46, p[Formula: see text] 0.001; HR 0.64, p = 0.011; and HR 0.51, p = 0.005, respectively] and OS (HR 0.55, p = 0.002; HR 0.48, p = 0.004; and HR 0.42, p < 0.001, respectively). For patients aged < 3years, both RT and HDC/ASCR were significant favorable factors for PFS (HR 0.32 and 0.46, respectively) and OS (HR 0.40 and 0.36, respectively), while early RT was not prognostic. For patients aged ≥ 3years, early RT was significantly associated with better PFS (HR 0.51) and HDC/ASCR did not affect PFS, and neither was related to OS. Both early RT initiation and HDC/ASCR were important components in the treatment of pediatric ATRT. However, the optimal treatment strategies might differ by age.

Impact of multidisciplinary tumor board discussion on palliation of patients with esophageal or gastro-esophageal junction cancer: a population-based study

Background: The Dutch guidelines for esophageal and gastro-esophageal junction (GEJ) cancer recommend discussion of patients by a multidisciplinary tumor board (MDT). Despite this recommendation, one previous study in the Netherlands suggested that therapeutic guidance was missing for palliative care of patients with esophageal cancer. The aim of the current study was therefore to assess the impact of an MDT discussion on initial palliative treatment and outcome of patients with esophageal or GEJ cancer.Material and methods: The population-based Netherlands Cancer Registry was used to identify patients treated for esophageal or GEJ cancer with palliative intent between 2010 and 2017 in 7 hospitals. We compared patients discussed by the MDT with patients not discussed by the MDT in a multivariate analysis. Primary outcome was type of initial palliative treatment. Secondary outcome was overall survival.Results: A total of 389/948 (41%) patients with esophageal or GEJ cancer were discussed by the MDT before initial palliative treatment. MDT discussion compared to non-MDT discussion was associated with more patients treated with palliative intent external beam radiotherapy (38% vs. 21%, OR 2.7 [95% CI 1.8–3.9]) and systemic therapy (30% vs. 23%, OR 1.6 [95% CI 1.0–2.5]), and fewer patients treated with stent placement (4% vs. 12%, OR 0.3 [95% CI 0.1–0.6]) and best supportive care alone (12% vs. 33%, OR 0.2 [95% CI 0.1–0.3]). MDT discussion was also associated with improved survival (169 days vs. 107 days, HR 1.3 [95% CI 1.1–1.6]).Conclusion: Our study shows that MDT discussion of patients with esophageal or GEJ cancer resulted in more patients treated with initial palliative radiotherapy and chemotherapy compared with patients not discussed by the MDT. Moreover, MDT discussion may have a positive effect on survival, highlighting the importance of MDT meetings at all stages of treatment.

Abstract P4-12-19: Impact of delaying initiation of RT following definitive surgery or following adjuvant chemotherapy on survival outcomes in breast cancer patients

Abstract Purpose: For breast cancer (BC) patients treated with adjuvant chemotherapy (CT), the optimal time to initiation of adjuvant radiotherapy (TTR) from definitive surgery is still controversial especially with modern systemic therapy, while the impact of TTR from completion of CT has not been reported to date. The current study aims to evaluate the impact of TTR from surgery and from completion of CT on survival outcomes in non-metastatic BC patients according to BC subtype. Methods and Materials: BC patients who were treated with definitive surgery followed by adjuvant CT and received adjuvant radiotherapy (RT) from January 2009 through December 2015 in a single institution were included in this study. Patients receiving neoadjuvant therapy were not enrolled. According to our clinical practice, if adjuvant treatments were well organized, RT could be initiated within 180 days following surgery and with completion of most up-to-date CT regimens. As a result, patients were categorized into two groups according to TTR from surgery as ≤180 and &amp;gt;180 days and according to TTR from CT as ≤12 and &amp;gt;12 weeks. The survival curves were estimated by the Kaplan-Meier method and compared by log-rank test. The independent effect of TTR from surgery and TTR from CT were separately tested using a Cox proportional hazards model for multivariate analysis after adjusting for these variables that were statistically significant on univariate analysis. Results: In total, 989 patients were enrolled. The number of patients with HR-positive, triple-negative (TN) and HER2-positive BC was 590, 196, and 203, respectively. The median follow-up was 43 (range: 4 to 117) months. The median TTR from surgery was 180 (range: 24 to 117) days and from completion of CT was 29 (range: 7 to 247) days. The 5-year recurrence-free survival (RFS), locoregional RFS (LRRFS), distant RFS (DRFS) and overall survival (OS) were 88.0%, 96.9%, 89.3% and 93.5%, respectively. The 5-year OS was 94.7%, 88.3% and 95.2% in patients with HR-positive, TN and HER-2 positive BC, respectively (P&amp;lt;0.01). Initiation of RT &amp;gt;12 weeks after completion of CT was associated with worse OS (5-year 94.0% vs 85.1%, p=0.006), &amp;gt;180 days after surgery was associated with worse DRFS (5-y 91.7% vs 86.9%, p=0.004) and worse RFS (5-y 90.7% vs 85.4%, p=0.003). In the multivariable analysis, TTR after completion of CT remained independent prognostic factor for OS (hazard ratio [HR], 2.81; 95% CI, 1.17 to 6.74; P=0.02) and TTR &amp;gt;180 days after surgery was also significantly associated with worse DRFS (HR, 1.79; 95% CI, 1.09 to 2.93; P=0.02) and RFS (HR, 1.71; 95% CI, 1.09 to 2.69; P=0.02). In patients with HR-positive BC, TTR &amp;gt;12 weeks after completion of CT was significantly associated with worse OS, while &amp;gt;180 days after surgery was with adverse DRFS (5-y 91.0% vs. 83.8%, p=0.004), RFS (5-y 89.8% vs. 82.8%, p=0.003), and OS (5-y96.6% vs 91.8%, p=0.026). However, these associations between TTRs and survival outcomes were not found in patients with HER2-positive BC or TNBC. Conclusion: In BC patients indicated for CT, delaying initiation of RT after definitive surgery or after completion of CT both adversely impact on survival outcomes. Efforts should be made to minimize delays in the initiation of RT in the above two TTR settings. Citation Format: Lu Cao, Jia-Yi Chen. Impact of delaying initiation of RT following definitive surgery or following adjuvant chemotherapy on survival outcomes in breast cancer patients [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-12-19.