Delay In Radiotherapy Research Articles

The effect of radiation therapy on post-prostatectomy urinary function

We sought to evaluate the effect of radiation therapy on post-prostatectomy urinary quality of life in prostate cancer patients. In some men with non-metastatic prostate cancer, radiation therapy is indicated following prostatectomy. The radiation toxicity and quality of life considerations are unique in the post-prostatectomy setting. A total of 106 patients receiving post-prostatectomy radiation therapy completed the Expanded Prostate Cancer Index Composite questionnaire before radiation and at 2-year follow-up. The primary outcomes of this study were the urinary domain summary score and subscale scores. Planned analysis was performed based on time interval from prostatectomy to radiation therapy. Among the 106 patients analyzed, the mean urinary domain summary score worsened at 2-year follow-up after radiation therapy, lowering from 77.23-72.51 (p = 0.0085). Similar worsening was observed in the subscales of function (p = 0.003), bother (p = 0.0397), and incontinence (p = 0.0003). Urinary incontinence showed the greatest observable change among subscales. While the summary score worsened (p = 0.0031) among patients receiving radiation therapy more than 1 year after prostatectomy, it did not show statistically significant change in those treated 1 year or less after prostatectomy. Our results demonstrate that post-prostatectomy radiation therapy is associated with modest declines in reportable urinary quality of life. Patients receiving radiation therapy more than 1 year after prostatectomy showed greater worsening of urinary quality of life, which indicates that there may be no functional advantage to delaying radiation therapy beyond the initial postoperative period.

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

Optimal Timing of Radiotherapy Following Gross Total or Subtotal Resection of Glioblastoma: A Real-World Assessment using the National Cancer Database

Treatment for glioblastoma (GBM) includes surgical resection and adjuvant radiotherapy (RT) and chemotherapy. The optimal time interval between surgery and RT remains unclear. The National Cancer Database (NCDB) was queried for patients with GBM. Overall survival (OS) was estimated using Kaplan-Meier and log-rank tests. Univariate (UVA) and multivariable Cox regression (MVA) modeling was used to determine predictors of OS. A total of 45,942 patients were included. On MVA: younger age, female gender, black ethnicity, higher KPS, obtaining a gross total resection (GTR), MGMT promoter-methylated gene status, unifocal disease, higher RT dose, and RT delay of 4–8 weeks had improved OS. Patients who underwent a subtotal resection (STR) had worsened survival with RT delay ≤4 weeks and patients with GTR had worsened survival when RT was delayed >8 weeks. This analysis suggests that an interval of 4–8 weeks between resection and RT results in better survival. Delays >8 weeks in patients with a GTR and delays <4 weeks in patients with a STR/biopsy resulted in worse survival. This impact of time delay from surgery to RT, in conjunction with extent of resection, should be considered in the clinical management of patients and future designs of clinical trials.

Round Block Technique Versus Reduction Mammoplasty in Treatment of Early Breast Cancer

Abstract Background Early breast cancer can be defined as the presence of a mobile tumor within the breast with or without associated mobile enlarged lymph nodes, and represents the vast majority of patients who present now with breast cancer. Breast-conserving treatment (BCT) has become the standard treatment in early-stage breast cancer; Its goal is to provide a treatment as effective as mastectomy, with the added benefit of a preserved breast. Aims The aim of the study is the comparison between Round block technique and Reduction mammoplasty in management of early breast cancer. Methodology This is a prospective controlled clinical study which included 30 patients, who were admitted to Ain Shams University Hospitals, with a diagnosis of early breast cancer T1 or T2, N0 or N1, M0. Patients were subdivided into 2 groups: Group I: This group is composed of 15 patients with early breast cancer (T1 or T2, N0 or N1, MO) underwent\Round block rechnique. Group II: This group is composed of 15 patients with early breast cancer (T1 or T2, N0 or N1, MO) underwent Reduction mammoplasty. Results In our study, there was no significant statistical difference between the two groups regarding: patients age, our patients were younger in comparable to other studies as we reported average age 47(30-62 years) and 43 (30-64 years). Family history, as 2(40%) and 1(30%) in first degree family members. Side of the lesion (mass), was in right breast in (53.3%) and (60%) in group (I) (Round block group) and group(II) (Reduction mammoplasty group), respectively. There was a significant difference, between the two groups as regard: Intraoperative blood loss, intraoperative time, hospital stay, postoperative complication and cosmetic outcome Conclusion Oncoplastic surgery gives a new tool for the treatment of breast cancer as much larger volume of breast tissue can be excised, and wider surgical margins can be achieved especially for larger tumors with better cosmetic outcome, in which a standard resection can lead to poor cosmetic results and tumor-involved surgical margins. Patients with early breast cancer with medium size breast with no major ptosis that are candidate for Round block technique and reduction mammoplasty, round block technique is better for them as there is less morbidity, less complications so no delay in radiotherapy, better cosmesis, mostly doesn’t need contralateral breast surgery for symmetrization and Reduction mammoplasty needs more surgeon’s experience.

Infrastructural Challenges Lead to Delay of Curative Radiotherapy in Nigeria.

PURPOSEIn low- and middle-income countries, there has been an exponential increase in cancer incidence. According to the International Atomic Energy Agency, the biggest gap in radiotherapy availability and need is in Nigeria, where each machine serves an estimated 25.7 million people. This study aimed to characterize the barriers to radiotherapy and to identify areas for intervention.METHODSThis was a cross-sectional study conducted at the University College Hospital in Ibadan, Nigeria, from June 2017 to August 2017. Demographic, sociocultural, and infrastructural factors relating to radiotherapy were collected through a questionnaire (N = 186). Ordinal logistic regression was used to identify the factors leading to delays in referral and delays in treatment initiation.RESULTSPatients traveled from 20 of Nigeria’s 36 states. The median age was 50 years (range, 19-79 years). The most common cancers treated were breast (37.5%), cervical (16.3%), head and neck (11.9%), and prostate (10.9%). In ordinal logistic regression, sociocultural factors, including the inability to pay (odds ratio [OR], 1.99; P = .034), a bad hospital experience (OR, 7.05; P = .001), and travel time (OR, 1.36; P = .001), increased the odds of referral delay to radiotherapy. In contrast, there was no significant relationship between time to treatment initiation and sociocultural factors including age, education, and inability to pay. Infrastructural barriers, including machine breakdown (OR, 2.92; P = .001), worker strikes (OR, 2.64; P = .001), and power outages (OR, 2.81; P = .022), increased the odds of treatment delay.CONCLUSIONAlthough delays caused by patient factors are reported extensively, patients overcame these barriers in the hopes of curative treatment. However, staff and equipment malfunctions prevented patients from receiving timely radiotherapy. Policies aimed at addressing machine maintenance, health care worker satisfaction, and the aging power grid in Nigeria must be implemented in the future to strengthen the health care system to care for patients with cancer.

Delays in radiation therapy as a result of insurance peer-to-peer prior authorizations among lung cancer patients

Lung cancer is the leading cause of cancer death in the USA and timely treatment plays a major role in the prognosis. Peer-to-peer insurance prior authorizations are believed to represent a major cause of treatment delays. However, the effect of peer-to-peer prior authorizations on radiotherapy treatment delays in lung cancer remains unknown. We reviewed departmental treatment records between September 2015 and 2018 for patients who received radiation therapy (RT) with curative intent for lung cancer. Our primary endpoint was delay in RT initiation; delay in RT simulation served as a secondary endpoint. Univariate and multivariate logistic regressions were used to estimate the effect of peer-to-peer reviews on treatment delays of at least 7 days. Two hundred and seventy patients were included. The median treatment delay was 6.5 days for those requiring peer-to-peer review versus 1 day for those who did not (Wilcoxon rank-sum test, p = 0.002). Univariate logistic regression found peer-to-peer review to be strongly correlated with a delay in start of treatment (OR = 3.58, p = 0.002) and simulation (OR = 9.24, p < 0.001); this effect persisted on multivariate analysis. Time trend analysis found that utilization of peer-to-peer reviews increased in frequency over our study period (p < 0.001). Peer-to-peer reviews were strongly correlated with delay in RT treatment and planning. This insurance practice has additionally become more prevalent over time. A more streamlined process is needed to address this issue.

EP1.16-24 Overcoming Appointment Delay in Radiotherapy: A Single Institution Experience

EP1.16-24 Overcoming Appointment Delay in Radiotherapy: A Single Institution Experience

Impact of Delay in Initiation of Radiation Therapy in Newly Diagnosed Glioblastoma Patients after Gross Total Resection

Newly diagnosed glioblastoma (GBM) is treated with surgery followed by radiation therapy (RT) and temozolomide (TMZ). We evaluated the impact on clinical outcomes of a delay in the initiation of RT for newly diagnosed GBM patients who have undergone a gross total resection (GTR). Consecutive GBM patients who underwent GTR and were treated at our institution from 2005-2014 were investigated. Patient, tumor, and treatment details were abstracted from the electronic medical record. A delay in RT start was defined as interval from surgery to RT initiation of over 5 weeks (35 days). Kaplan-Meier and Cox proportional hazards modeling were used to evaluate overall survival (OS) and recurrence-free survival (RFS). We identified 179 GBM patients with a median age of 59 years (range 22-87) who underwent GTR. 94% had KPS ≥ 70. Median RT dose was 60 Gy and 93% received concurrent TMZ with RT. Among 110 patients with known MGMT methylation status, 51% were methylated. The median interval from diagnosis to RT start was 28 days (range 10-93) and 32 patients (17%) had an RT delay (start > 5 weeks after diagnosis). There was an explicit medical reason for delay (e.g. wound healing, hospitalization, management of other malignancy) in 7 patients. Among those with RT delay, MGMT was methylated in 47%. Median age was 59 years versus 58 years in those without a delay (p = 0.4). 90% had KPS ≥ 70 versus 95% of those without RT delay (p = 0.4). On univariable analysis (UVA), a delay in RT start was associated with inferior OS (HR 1.66, 95% CI 1.05-2.66, p=0.03). Crude median OS was 19.5 months for patients with RT delay vs. 26.9 months in patients without RT delay. On multivariable analysis (MVA) with RT delay, age, MGMT methylation status, and KPS < 70 as covariates, age (AHR 1.05, 95% CI 1.03-1.08, p < 0.001) was significantly associated with OS and MGMT methylation was near-significant (AHR 0.63, 0.37-1.07, p = 0.09), while RT delay was not significant (AHR 0.83, 95% CI 0.41-1.65, p = 0.59). RT delay was associated with inferior RFS on UVA (HR 1.65, 95% CI 1.09-2.51, p = 0.02), but this did not hold on MVA (AHR 0.96, 0.54-1.70, p=0.9). Age (AHR 1.02, 95% CI 1.00-1.05, p = 0.02) and MGMT methylation (AHR 0.44, 95% CI 0.28-0.70, p<0.001) were associated with improved RFS. Among GBM patients with GTR, patients with RT delay > 5 weeks had inferior OS and RFS relative to patients without a delay, but there was no significant difference after adjustment for clinical covariates.

Delays in Radiation Therapy as a Result of Peer to Peer Review Process

Delays in Radiation Therapy as a Result of Peer to Peer Review Process

Prolonged Interval between Initiation of Neoadjuvant Chemotherapy and Radiotherapy Impairs Long Term Survivals in Locoregionally Advanced Nasopharyngeal Carcinoma

Longer waiting time for radiotherapy (RT) has been associated with inferior survival in nasopharyngeal carcinoma (NPC), but this effect is unclear with the inclusion of neoadjuvant chemotherapy (NACT). Our study aimed to investigate the impact of time factor between NACT and RT in locoregionally advanced NPC. Clinical data on 577 patients with locoregionally advanced NPC treated with intensity-modulated radiotherapy (IMRT) were retrospectively reviewed. The optimal cut-off value of time interval was identified using a “surv_cutpoint” function in R software. Overall survival (OS), locoregional relapse-free survival (LRFS), distant metastasis-free survival (DMFS) and disease-free survival (DFS) were estimated using the Kaplan–Meier method. Univariate and multivariable survival analyses were performed with Cox proportional hazards models. Univariate analysis showed that patients with longer interval between initiation of NACT and RT (≥70 days) had significantly worse OS (81.9% vs. 68.0%, P=0.012), DMFS (83.6% vs. 63.9%, P=0.001) and DFS (69.4% vs. 51.4%, P=0.001), compared those with shorter waiting time. This difference remained significant when stratified by N classification and cycles of NACT (≤2 vs. >2) (P<0.05). No difference was observed in LRFS. After adjusting for clinical variables including age, sex, T and N classification, treatment modality and cumulative cisplatin dose, multivariable models revealed that time interval (≥70 days) was an independent predictor for OS (HR 1.88, 95%CI: 1.16-3.03, p=0.011), DMFS (HR 2.08, 95%CI: 1.27-3.41, p=0.004) and DFS (HR 1.83, 95%CI: 1.24-2.69, p=0.002). Severe delay of radiotherapy by NACT may detriment long-term survivals for locoregionally advanced NPC patients, most likely through enhanced distant metastasis rate. Long-course NACT and extended RT planning process should be avoided.

Wilm's Tumor-Collaborative Approach is needed to Prevent Tumor Upstaging and Radiotherapy Delays: A Single Institutional Study

Abstract Context: Successful management of Wilm's tumor (WT) necessitates meticulous attention for proper staging and collaborative effort for its optimal management. Aims: The aim of the study was to observe the patterns of WT. Settings and Design: This study was a single-institutional retrospective study. Subjects and Methods: Twenty-three WT case records were analyzed over 6 years and the data collected were interpreted as number, percent, mean ± and standard deviation with regard to clinicodemographic aspects, staging, and diagnostic modality and treatment options. Results: Mean age was 3.97 ± 2.67 years with maximum number in the 2–5-year age group. Males slightly dominated the number, and majority cases were from the rural area. The major clinical presentation was abdominal mass followed by abdominal pain, fever, vomiting, hematuria, and urinary retention. Left laterality was common and single bilateral WT was seen. Majority of tumors were &gt;10 cm in their largest dimensions. Most WT presented in Stage III followed by Stage I and IV. One was a recurrent tumor. Conclusion: WT was usually diagnosed at the locally advanced or metastatic stages; hence, the comprehensive collaborative approach will help to manage the patients optimally and avoid tumor upstaging and radiotherapy delays. Besides awareness at community level is needed to pick up the disease at the earlier stage to have a better outcome in the form of disease control and disease-free survival.

ONCOPLASTIC TECHNIQUES FOR EARLY UPPER INNER QUADRANT BREAST CANCER; A COMPARATIVE STUDY BETWEEN INFERIOR PEDICLE MAMMAPLASTY AND DOUGHNUT MASTOPEXY

Background: Breast conserving treatment (BCT) has become the standard treatment in early breast cancer; its goal is to provide a treatment as effective as mastectomy with the added benefit of a preserved breast. However, it is sometimes difficult to achieve good cosmetic results, particularly in patients with breast cancer located in the upper inner quadrant, for which the traditional conservative surgery results in a deformed breast. Aim of the work: To compare prospectively the oncoplastic results of inferior pedicle mammaplasty and doughnut mastopexy as techniques for early breast cancers located at the upper inner quadrant. Patients and Methods: This is a prospective randomized study on twenty female patients who were diagnosed to have early breast cancer located in the upper inner quadrant and are candidates foroncoplastic breast surgery. The study was conducted at Ain Shams University Hospitals. Approval of the Ethical Committee and written informed consent from all participants were obtained. Patient selection was achieved through a number of inclusion and exclusion criteria. Results: There is significant difference between the two groups as regards the operative time, intraoperative blood loss, hospital stay, total drainage volume, drainage days, postoperative complications,cosmetic outcome and the need for contralateral symmetrization. Inferior pedicle mammaplasty needs longer operative time and postoperative hospital stay and drainagy days with more intraoperative blood loss in comparison to Doughnut mastopexy. As regards the postoperative complications, we found that there are more complications in Inferior pedicle mammaplasty than Doughnut mastopexy as wound wound infection and dehiscence. Conclusion: Patients with early breast cancer located in the upper inner quadrant are candidate for either Inferior pedicle mammaplasty or Doughnut mastopexy. Doughnut mastopexy is better for them as there is less morbidity, better cosmesis, no need for contralateral symmetrization and fewer complications, so no delay in radiotherapy and Inferior pedicle mammaplasty needs more surgeon experience.

Timing of adjuvant radiation therapy and survival outcomes after surgical resection of intracranial non-small cell lung cancer metastases

Objective: To investigate if delay of adjuvant radiotherapy (ART) beyond 6 post-operative weeks affects survival outcomes in patients undergoing craniotomy or craniectomy for resection of non-small cell lung cancer (NSCLC) intracranial metastases. Patients and methodsWe performed a retrospective analysis of 28 patients undergoing resection of intracranial metastases and ART at our institution from 2001 to 2016. We assessed survival outcomes for patients who received delayed versus non-delayed ART, as well as associated risk factors. ResultsAmong 28 patients, 8 (29%) had delayed ART beyond 6 post-operative weeks. Fifteen received stereotactic radiotherapy (SRT), 8 (29%) received whole brain radiotherapy (WBRT), and 5 (18%) received combination WBRT + SRT. There were no significant differences in ART modality or dosing, age, sex, number of intracranial metastases, primary metastasis volume, rates of chemotherapy, extracranial metastases, or post-operative functional scores between groups. Expected post-operative survival was shorter with delayed ART (7 months versus 28 months, P = 0.01). The most common reason for delayed ART was complicated post-operative course (n = 3.38%). Significant risk factors for delayed ART included non-routine discharge (P = 0.01) and additional invasive procedures between surgery and ART start date (P = 0.02). ConclusionsOur results suggest delayed ART in patients undergoing surgical resection of intracranial NSCLC metastases is associated with shorter overall survival. However, risk factors for delayed ART, including non-routine discharge and the need for additional invasive procedures, may have in themselves reflected poorer clinical courses that may have also contributed to the observed survival differences.

Induction chemotherapy with docetaxel, cisplatin and cetuximab versus docetaxel, cisplatin and 5-fluorouracil followed by radiotherapy with cetuximab for locally advanced or inoperable squamous cell carcinoma of the head and neck: Promising results of a randomized phase II AGMT-trial.

6027 Background: Induction chemotherapy (ICT) with Cisplatin (P), 5-FU (F) and Taxanes (T) is a therapeutical option in patients suffering from locally advanced or unresectable stage III or IV squamous cell carcinoma of the head and neck (SCCHN). The role of ICT is controversial and toxicity and/or delay of radiotherapy may reduce the potential benefit of this treatment regimen. Here we report promising results of a randomized phase II trial comparing TPF with TP and Cetuximab (C) replacing F. Methods: In our trial, N= 100 patients with locally advanced or unresectable stage III or IV SCCHN were randomly assigned to either Arm A ( N= 49), receiving TPF, or Arm B ( N= 51), receiving TPC, both followed by radiotherapy (RT) + C. The primary end-point of the study was overall response rate (ORR) three months after RT + C was finished. Results: We observed a remarkable response rate (CR + PR) of 86.4% in the TPC-arm that compared favorably with 77.5% responding patients in the TPF-arm three months after RT + C was completed. OS and PFS were similar in both arms. After 400 days we observed an OS rate of 79% in the TPF and 86% in the TPC arm, and a PFS rate of 67% in the TPF and 70% in the TPC arm. TPC containing ICT led to less serious adverse events (SAEs), including blood and lymphatic disorders (40.8% in TPF arm, 27.5% in TPC arm) and metabolism and nutrition disorders (22.4% in TPF arm, 9.8% in TPC arm) during ICT. Interestingly, in HPVp16 positive patients, 88.24% in the TPF-arm and 93.33% in the TPC-arm showed CR or PR three months after RT + C, whereas only 69.57% in the TPF-arm and 82.76% in the TPC-arm showed CR or PR. We only lost one patient because of treatment-related mortality (TRM) and no delay from the end of ICT to local radiotherapy was observed in any patient. All patients received RT + C within three weeks after ICT was completed. Conclusions: In conclusion, TPC is a feasible and tolerable therapy regimen and can be applied within one day with less hematological toxicities. In contrast, more local reactions were observed after TPC. TPC containing ICT leads to improved response rates, while OS and PFS were similar in both arms. TRM was extremely low with 1%. Therefore, we conclude, that TPC containing ICT could be a considerable therapeutical alternative for patients with locally advanced or unresectable stage III or IV SCCHN, who are eligible for ICT. Clinical trial information: 2011-005540-99.

Role of early and aggressive post-operative radiation therapy in improving outcome for pediatric central nervous system atypical teratoid/rhabdoid tumor.

The purpose of the study is to evaluate possible prognostic factors and optimal management for pediatric atypical teratoid/rhabdoid tumor (AT/RT) of the central nervous system (CNS). Twenty-eight pediatric patients with CNS AT/RT who were treated with radiation therapy (RT) as part of multimodality treatment regimens at a single institution (1996-2015) were reviewed. Survival outcomes were analyzed in relation to possible prognostic factors. The 28 patients analyzed were followed up for a median 48-month period. Median progression-free survival (PFS) was 11months, and overall survival (OS) was 57months. Patients < 3years old had RT delayed for a longer period after surgery (p = 0.04), and the mean RT dose to tumor bed was lower (p < 0.01) than in patients ≥ 3years old. In multivariate analysis, a higher primary tumor bed RT dose was identified as a favorable prognostic factor for both PFS (hazard ratio [HR] = 0.85 per gray, p < 0.01) and OS (HR = 0.92 per gray, p = 0.02). In addition, an interval between surgery and RT initiation > 2months, with disease progression observed before RT, as compared with an interval ≤ 2months without disease progression prior to RT, was associated with worse PFS (HR = 8.50, p < 0.01) and OS (HR = 5.27, p < 0.01). Early and aggressive RT after surgery is critical for successful disease control in AT/RT patients. Conversely, a delay in RT until disease progression is observed that leads to unfavorable outcomes.

EP-1657 Overcoming appointment delay in radiotherapy: a single institution experience

EP-1657 Overcoming appointment delay in radiotherapy: a single institution experience

Abstract P5-13-18: Barriers to adjuvant radiotherapy treatment for breast cancer in a teaching hospital in Brazil

Abstract BACKGROUND: Adjuvant treatment of non-metastatic breast cancer (BC) represents an important paradigm of multimodality approach in oncology practice, with an established role for radiotherapy (RT). A delay of adjuvant radiotherapy can lead to poorer results. When chemotherapy (CT) is not indicated, RT should be initiated within 8 weeks after surgery. If CT is administered first, RT should be started within 7 months from surgery, since there is a continuous relation between time to radiotherapy and local recurrence. Brazil's public healthcare system, SUS, faces many challenges caring for cancer patients: inadequate funding, inequitable distribution of resources and services, among others. According to research done by Lins et al, around 458 linear accelerators would be necessary to supply the Brazilian public health demand and end the waiting line for radiation therapy. Currently, our healthcare system has 283 machines, which are responsible for more than 70% of our population. Furthermore, patients lack understanding of treatment windows, which is an additional hurdle. METHODS: We randomly selected 122 charts of female BC patients submitted to treatment with curative intent from 2003-2017 in Hospital das Clínicas da UFMG, the biggest teaching hospital of the 3rd largest city in Brazil. Primary endpoint was to determine median time from surgery to adjuvant radiotherapy, and second point was to determine median radiotherapy time. RESULTS: Twenty eight patients were not included in the analysis, 26 due to lack of information in the charts and two for not having received the proposed radiotherapy. Ninety four patients were included: median age was 49 years old (21-90), 21.5% were stage I, 41.9% stage II and 34.4% stage III at diagnosis. Patients received chemotherapy (neo or adjuvant), hormonotherapy, or both, according to oncologists discretion. All patients were submitted to surgery and radiotherapy. Long median times from referral to RT initiation and to radiotherapy completion were identified: 54 days and 97 days, respectively, as well as 7 months from surgery to beginning of RT (1-16) and 9 months from diagnosis to its completion (2-29).Biopsies were performed in 27 different sites and RT in 12. IntervalMedian Time (days)Biopsy to results13 (1-77)Referral to RT initiation54 (1-238)Referral to RT completion97 (43-238)RT initiation to RT completion42 (20-80) IntervalMedian Time (months)Surgery to RT initiation7 (1-16)Diagnosis to RT completion9 (2-29) CONCLUSIONS: This study shows that intervals for completion of adjuvant radiotherapy are well above recommended, mostly due to long delays in initiating radiotherapy. Although in our study all patients were conducted by the same oncology team, the system is fragmented, making it even more difficult for patients to receive multidisciplinary care and improve prognosis. There is undeniable need for more radiotherapy machines, but since their acquisition depends on costly governmental actions, we need to think about strategies that may allow us to better use the resources already available. We believe that Patient Navigation plays an important role here and were are establishing this program in our institution with Global Cancer Institute support. Citation Format: Vieira CM, Nogueira-Rodrigues A, Sousa CF, Krush L, Goss PE. Barriers to adjuvant radiotherapy treatment for breast cancer in a teaching hospital in Brazil [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-13-18.

Machine Learning to Predict Delays in Adjuvant Radiation following Surgery for Head and Neck Cancer.

To apply a novel methodology with machine learning (ML) to a large national cancer registry to help identify patients who are high risk for delayed adjuvant radiation. Observational cohort study. National Cancer Database (NCDB). A total of 76,573 patients were identified from the NCDB who had invasive head and neck cancer and underwent surgery, followed by radiation. The model was constructed from 80% of the patient data and subsequently evaluated and scored with the remaining 20%. Permutation feature importance analysis was used to understand the weighted model construction. A total of 76,573 patients met inclusion and exclusion criteria. Our ML model was able to predict whether patients would start adjuvant therapy beyond 50 days after surgery with an overall accuracy of 64.41% and a precision of 58.5%. The 2 most important variables used to build the model were treating facility and urban versus rural demographics. Statistics can provide inferences within an overall system, while ML is a novel methodology that can make predictions. We can identify patients who are "high risk" for delayed radiation using information from >75,000 patient experiences, which has the potential for a direct impact on clinical care. Our inability to achieve greater accuracy is due to limitations of the data captured by the NCDB, and we need to continue to identify new variables that are correlated with delayed radiation therapy. ML will prove to be a valuable clinical tool in years to come, but its utility is limited by available data.

Delayed Radiation Therapy is Associated with Improved Overall Survival in Node Positive Prostate Cancer Treated with Androgen Deprivation Therapy

Delayed Radiation Therapy is Associated with Improved Overall Survival in Node Positive Prostate Cancer Treated with Androgen Deprivation Therapy

Oligodendroglioma Patients with 1p/19q Co-deletion Treated with Early or Delayed Radiation Therapy over the Last Two Decades: A Multi-institutional Report

To evaluate the patterns of care and clinical outcomes of irradiated oligodendroglioma patients using a pooled analysis of a multi-institutional cohort. Oligodendroglioma patients with confirmed 1p/19q co-deletion who were treated with radiation therapy (RT) with or without chemotherapy from 2000-2017 at four tertiary academic cancer centers were retrospectively reviewed. PFS and OS rates were determined with Kaplan-Meier analyses. Logistic regression analysis was used to identify factors associated with delayed use of RT. Cox regression analysis was used to identify factors associated with worse progression free survival (PFS) and overall survival (OS). Progression was defined as progression after RT, whether RT was delivered adjuvantly or in a delayed fashion. All times to progression or death were determined from the time of initial surgery. One hundred eighty-eight patients were identified: 122 (65%) received early RT (within 6 months of surgery, median: 1.2 months, range: 0.03-5.6 months), and 67 (35%) received delayed RT (more than 6 months from surgery, median: 50 months, range: 6.3-213 months). Most patients were treated with intensity-modulated RT (65%) followed by 3D conformal RT (23%) and proton therapy (12%). Median age and follow up was 43 years (range 20-80) and 69 months (range 2-242), respectively. For patients who were treated with early RT, 70% were treated with RT and temozolomide (TMZ), and 15% were treated with RT and procarbazine/lomustine/vincristine (PCV), and 15% were treated with RT alone. For patients who were treated with delayed RT, 36% patient were treated with initial chemotherapy and then salvage RT later, 46% were treated with RT +TMZ, 13% were treated with RT+PCV, and 5% were treated with RT alone. Ten-year PFS for early RT and delayed RT were 63% vs. 74%, respectively (P=0.02); ten-year OS for early RT and delayed RT were 67% vs. 91%, respectively (P=0.02). Younger age (OR = 1.04, 95% CI 1.02-1.07) and grade 2 histology (OR = 7.0, 95% CI 3.4 -14.2) were associated with delayed RT. Gliomatosis (HR = 46, 95% CI 5.1-422) and grade 3 histology (HR = 2.2, 95% CI 1.3-3.9) were significantly associated with worse PFS after RT. Older age (HR = 1.06, 95% CI 1.03-1.09), lower performance status (HR = 1.04, 95% CI 1.01-1.08), gliomatosis (HR = 42.7, 95% CI 4.5-401), and early RT (HR = 2.4, 95% CI 1.03-5.6) were associated with worse OS. In this large multi-institutional cohort with treatment spanning over two decades, oligodendroglioma patients had favorable prognosis regardless whether treated with early or delayed RT. Young age and grade 2 histology were more likely to receive delayed RT, which was not associated with significantly worse PFS or OS. Among this molecularly homogenous oligodendroglioma population with 1p/19q co-deletion, grade 3 histology was prognostic for PFS after RT but not OS. When chemotherapy was chosen to combine with either early or delayed RT, TMZ was preferentially chosen over PCV.