Post-treatment Positron Emission Tomography-computed Tomography Research Articles

Post-treatment PET/CT for p16-positive oropharynx cancer treated with definitive proton therapy.

Given emerging data suggesting that uncertainty in the relative biologic effectiveness at the distal end of the Bragg peak results in increased mucosal injury in patients with oropharynx cancer receiving adjuvant proton therapy, we evaluated the results of post-treatment positron emission tomography-computed tomography (PET/CT) in patients with p16-positive oropharynx cancer (p16+OPC) treated with definitive intensity-modulated proton therapy (IMPT). A retrospective cohort study of patients with p16+OPC treated with definitive IMPT between 2016 and 2022 was performed at a single institution. Patients with PET/CT scans within 6 months following completion of IMPT were included in the study. Positive post-treatment scans were defined by a maximum standard uptake values (SUVmax) >4.0 or a <65% reduction in SUVmax in either the primary tumor or lymph node. The Fisher's exact test was used to evaluate factors associated with positive post-treatment PET/ CT values. Sixty-two patients were included for analysis. Median follow-up was 21 months (range: 3-71 months) with a median time to post-treatment PET/CT of 3 months (range: 2-6 months). Median post-treatment SUVmax of the primary disease and nodal disease was 0 (mean: 0.8, range: 0-7.7) and 0 (mean: 0.7, range: 0-9.5), respectively. Median post-treatment percent reduction in SUVmax for the primary site and lymph node was 100% (mean: 94%, range: 31.3-100%) and 100% (mean: 89%, range: 23-100%), respectively. Eleven patients had a positive post-treatment PET/CT with one biopsy-proven recurrence. Negative and positive predictive values (NPV and PPV) were 98% and 9.1%, respectively. There were no factors associated with positive post-treatment PET/CT. Similar to patients treated with photon-based radiation therapy, post-treatment PET/CT has a high NPV for patients with p16+OPC treated with definitive proton therapy and should be used to guide patient management. Additional patients and more events are needed to confirm the PPV of a post-treatment PET/CT in this favorable patient cohort.

The Effects of Human Papillomavirus Status and Treatment on the Positive Predictive Value of Post-radiotherapy 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in Advanced Head and Neck Squamous Cell Carcinoma

AimsThe high negative predictive value of post-chemoradiation (CRT) positron emission tomography-computed tomography (PET-CT) is well established in head and neck squamous cell cancers (HNSCC). The positive predictive value (PPV) remains under scrutiny, with increasing evidence that it is affected by several factors. The aim of this study was to assess the PPV of post-treatment PET-CT for residual nodal disease when stratified by treatment modality and tumour human papillomavirus (HPV) status. Materials and methodsThis was a retrospective cohort study in a tertiary oncology centre carried out between January 2013 and December 2019. Patients were radically treated with radiotherapy only/CRT for node-positive HNSCC. PET-CT nodal responses were categorised as complete, equivocal (EQR) or incomplete (ICR), and outcomes extracted from electronic records. ResultsIn total, 480 patients were evaluated, all had a minimum potential follow-up of 2 years, with a median of 39.2 months. The PPV of 12-week PET-CT was significantly different between HPV-positive (22.5%) and HPV-unrelated (52.7%) disease, P < 0.001. It was also significantly different between the CRT (24.8%) and radiotherapy-only (51.1%) groups, P = 0.001. The PPV of an EQR was significantly less than an ICR, irrespective of HPV status and primary treatment modality. In HPV-positive disease, the PPV of an EQR was 9.0% for the CRT group compared with 21.4% for radiotherapy only, P = 0.278. The PPV in those who achieved an ICR was 34.2% in the CRT group, significantly lower than 70.0% in the radiotherapy-only group, P = 0.03. ConclusionThe PPV of 12-week PET-CT is significantly lower for HPV-positive compared with HPV-unrelated HNSCC. It is poorer in patients with HPV-positive disease treated with CRT compared with radiotherapy alone.

55 Outcomes of FDG PET-CT in Surveillance of Residual Nodal Metastases Following Non-Surgical Management of Head and Neck Squamous Cell Carcinoma: A Retrospective Review

Abstract Aim Assessing the role of positron emission tomography-computed tomography (PET-CT) surveillance in detecting residual disease in nodal metastasis, following non-surgical treatment of Head and neck squamous cell carcinoma (HNSCC), such as chemoradiotherapy or radical radiotherapy. To analyse differences in outcomes between HPV positive and HPV negative cancers. Method Retrospective analysis of 327 patients in South Wales, with histologically proven HNSCC was conducted. All patients were treated non-surgically and post-treatment PET-CT scans were obtained. Patients with PET-CT showing incomplete responses had further analysis of outcomes assessed via surgical histology of the nodes. Outcomes in patients with p16 positive disease were recorded to determine outcomes in HPV positive individuals. Results 64 individuals had residual nodal tumours according to PET-CT. 18 out of 43 patients had a negative histology for malignancy, of which 12 showed p16 positive disease. PET-CT showed a false positive in 41.8% of patients, with a positive predictive value of 58%. 225 patients in total were p16 positive, and 38 out of the 64 residual patients had p16 positive disease. There was no significant difference in outcomes between p16 positive and negative patients. Conclusions Our study concurs with similar literature, that primary CRT in N2 and N3 nodal metastasis followed by PET-CT surveillance minimises unnecessary neck dissections and triple modality treatment. Further research needs to be conducted however, to determine the efficacy of PET-CT surveillance compared to planned neck dissections. Furthermore, outcomes in p16 positive patients requires additional ongoing research to best determine surveillance techniques and long-term health outcomes.

Does a 6-point scale approach to post-treatment 18F-FDG PET-CT allow to improve response assessment in head and neck squamous cell carcinoma? A multicenter study

PurposeResponse assessment to definitive non-surgical treatment for head and neck squamous cell carcinoma (HNSCC) is centered on the role of 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET-CT) 12 weeks after treatment. The 5-point Hopkins score is the only qualitative system available for standardized reporting, albeit limited by suboptimal positive predictive value (PPV). The aim of our study was to explore the feasibility and assess the diagnostic accuracy of an experimental 6-point scale (“Cuneo score”).MethodsWe performed a retrospective, multicenter study on HNSCC patients who received a curatively-intended, radiation-based treatment. A centralized, independent qualitative evaluation of post-treatment FDG-PET/CT scans was undertaken by 3 experienced nuclear medicine physicians who were blinded to patients’ information, clinical data, and all other imaging examinations. Response to treatment was evaluated according to Hopkins, Cuneo, and Deauville criteria. The primary endpoint of the study was to evaluate the PPV of Cuneo score in assessing locoregional control (LRC). We also correlated semi-quantitative metabolic factors as included in PERCIST and EORTC criteria with disease outcome.ResultsOut of a total sample of 350 patients from 11 centers, 119 subjects (oropharynx, 57.1%; HPV negative, 73.1%) had baseline and post-treatment FDG-PET/CT scans fully compliant with EANM 1.0 guidelines and were therefore included in our analysis. At a median follow-up of 42 months (range 5-98), the median locoregional control was 35 months (95% CI, 32-43), with a 74.5% 3-year rate. Cuneo score had the highest diagnostic accuracy (76.5%), with a positive predictive value for primary tumor (Tref), nodal disease (Nref), and composite TNref of 42.9%, 100%, and 50%, respectively. A Cuneo score of 5-6 (indicative of residual disease) was associated with poor overall survival at multivariate analysis (HR 6.0; 95% CI, 1.88-19.18; p = 0.002). In addition, nodal progressive disease according to PERCIST criteria was associated with worse LRC (OR for LR failure, 5.65; 95% CI, 1.26-25.46; p = 0.024) and overall survival (OR for death, 4.81; 1.07-21.53; p = 0.04).ConclusionsIn the frame of a strictly blinded methodology for response assessment, the feasibility of Cuneo score was preliminarily validated. Prospective investigations are warranted to further evaluate its reproducibility and diagnostic accuracy.

Leukemia Recurrence Exclusively in the Breast after Stem Cell Transplant

Introduction: Leukemic involvement of the breast is extremely rare but constitutes an oncologic emergency. Imaging findings of T-Cell acute lymphoblastic leukemia (T-ALL) recurrence in the breasts have not been previously described. Case Description: Patient is a 25 year old female who presented with symptoms of superior vena cava (SVC) obstruction secondary to a mediastinal mass status post biopsy demonstrating T-ALL, which was cluster of differentiation 3 (CD3) positive and B-cell lymphoma 2 (BCL-2), and 80% Ki-67 positive. She was treated with chemotherapy and post-treatment positron emission tomography/computed tomography (PET/CT) demonstrated resolution of mediastinal mass, with no evidence of distant disease. She underwent allogeneic hematopoietic stem cell transplant (HSCT) in first remission. Seven months post-HSCT, patient presented with a large area of tender swelling of both the breasts with biopsy demonstrating relapsed T-ALL. Radiologic findings showed bilateral breast masses on ultrasound and mammogram, which were hypermetabolic on PET/CT. Conclusions: Breast involvement in leukemia recurrence, a very rare entity, can present with palpable masses. Mammographic findings in leukemia can include masses or architectural distortion, they are typically hyperechoic on ultrasound, and can have marked uptake on PET/CT. Oncologists, primary care providers and radiologists should be aware of leukemia presentations in the breast for prompt referral for urgent management.

Post-treatment positron emission tomography-computed tomography is highly predictive of outcome in Plasmablastic lymphoma.

Plasmablastic lymphoma (PBL) is a rare variant of diffuse large B cell lymphomas (DLBCL) clinically characterized by a poorer prognostic. Few clinical and imaging data are available and derived from pooled case reports and small series. The aim of the study was to evaluate the FDG avidity at baseline and the utility of 18-Fluorodeoxyglucose (FDG) positron-emission-tomography/computed-tomography (PET/CT) for staging and response assessment. Patients with newly diagnosed PBL seen at Lymphoma Study Association centers during the period 2005-2015 were included if they underwent a PET/CT at staging and at the end of treatment (eotPET) and had received an anthracycline-based first line therapy. EotPET scans were analyzed using the 5-point-scale visual analysis in accordance with Lugano criteria. Patients were classified in complete metabolic response (CMR) or no-CMR including partial metabolic response (PMR), stable disease (SD) and progression disease (PD). EotPET results were assessed for the ability to predict event free survival (EFS) and overall survival (OS). Thirty-five PBL patients fulfilled the inclusion criteria. The median follow-up was 34months (2.8-120months). FDG avidity was found in all patients at diagnosis. Most patients (80%) achieved CMR, and 20% were no-CMR including 9% PMR, 6% SD, and 6% PD. A CMR after first line chemotherapy predicted higher EFS (p < 0.0001) and OS (p = 0.0006). This study confirmed the FDG avidity of PBL subtype and the usefulness of PET/CT scanning in restaging an aggressive lymphoma at the completion of chemotherapy. EotPET can predict outcomes following treatment in patients with PBL.

Extranodal diffuse large B-cell lymphomas: A retrospective case series and review of the literature.

Non-Hodgkin lymphomas commonly show extranodal involvement (25-30%) but primary diffuse large B-cell lymphomas (DLBCL) with extranodal localization represent clinically and molecularly distinct entities. The present study involved retrospective analysis of case records of 4 patients who were diagnosed with extranodal DLBCL between 2010 and 2016 at the Medical Oncology and Hematology Departments of the Ioannina University Hospital, Greece. Median age of presentation was 69 years (range 60-77 years). There were 2 males and 2 females. The sites of DLBCL involvement included adrenal gland, mandible, cervix uteri, and ileum. Two patients had B symptoms while none had bone marrow involvement. After staging workup, all the patients fell into IE stage. The treatment approach included chemotherapy combined with rituximab (R), whereas one patient received additionally irradiation therapy. Post-treatment positron emission tomography-computed tomography scan was performed in 3 patients. In terms of the outcome, 3 patients are alive in complete response, whereas one was lost in follow-up. Further prospective data analyses are required so as to better elucidate the biology and course of extranodal DLBCL.

Complete metabolic response (CMR) in positron emission tomography-computed tomography (PET-CT) scans may have prognostic significance in patients with marginal zone lymphomas (MZL).

Although clinical use of positron emission tomography-computed tomography (PET-CT) scans is well established in aggressive lymphomas, its prognostic value in marginal zone lymphoma (MZL) remains yet unclear. Hence, we investigated potential role of PET-CT in predicting MZL patients' outcomes following systemic chemotherapy. A total of 32 patients with MZL who received first-line chemotherapy were included in the analysis. They all underwent pretreatment, interim, and posttreatment PET-CT scans. The primary objective was to evaluate the role of complete metabolic response (CMR) in posttreatment PET-CT scans in predicting progression-free survival (PFS). Compared with non-CMR group, 5-year PFS rate was significantly higher in patients who achieved CMR in posttreatment PET-CT (54.2% vs 0.0%, P=.003) and also in patients gaining CMR in interim PET-CT scans (62.5% vs 15.6%, P=.026). Interestingly, early CMR group, who achieved and maintained CMR in both interim and posttreatment PET-CT scans, showed significantly higher 5-year PFS than those with delayed or never CMR group (62.5% vs 37.5% vs 0%, P=.008). Therefore, interim and/or posttreatment CMR can be prognostic at least in these subsets of patients with MZL treated with chemotherapy.

323P The role of SUVmax in 18F-FDG PET/CT for assessing radiation therapy response for cervical cancer

Background We assessed the relationship between primary tumor18F-fluorodeoxyglucose (FDG) uptake expressed as the maximum standardized uptake value (SUV max), primary tumor response, and survival in patients with cervical cancer on pretreatment and posttreatment positron emission tomography-computed tomography (PET-CT). Methods We conducted a retrospective review of 35 cervical cancer patients (stage I-II: n = 19; stage III-IV: n = 16) treated with radiation therapy with or without chemotherapy. All patients (median age, 58.5 years; range, 37~81 years) had FDG PET- CT scans performed before and after radiation therapy (pre- and post-RT). The SUV max were recorded from PET-CT scans performed pre-and post-RT. The correlation between SUV max and treatment response was evaluated and analyzed. Measurement of primary tumor volumes (pTV) for the treatment response evaluation was performed by the diagnostic radiologist using magnetic resonance imaging or abdominopelvic CT. Results The median duration of follow-up was 42 months (range 5-72 months). The median SUVmax of cervical cancer pre- and post-RT were 10.1 (range: 4.31~28.5) and 2.51 (range: 1.65~5.91), respectively. After treatment for cervical cancer, the reduction of SUVmax (median 7.4 (range: 0.05~25.85)) was significant (p < 0.001). There was a significant correlation between post-RT SUVmax and post-RT pTV (r=0.470, p=0.004). There was also a significant correlation between SUVmax reduction rate and pTV reduction rate (r=0.447, p=0.007). A significant correlation was observed between post-RT SUV max and the pTV reduction rate after RT (r=-0.534, p=0.001). Conclusions The SUVmax was significantly reduced after RT for cervical cancer. This study showed that the SUVmax after RT in patients with cervical cancer was significantly correlated with the primary tumor response. Legal entity responsible for the study Gachon University Gil Medical Center Funding Gachon University Gil Medical Center Disclosure All authors have declared no conflicts of interest.

Post-treatment PET-CT Findings may Predict the Prognosis of DLBCL with a Bulky Mass.

We retrospectively analyzed the prognosis of patients with diffuse large B cell lymphoma (DLBCL) and a bulky mass at diagnosis. We retrospectively analyzed clinical data for 29 consecutive DLBCL patients with an initial bulky mass receiving R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) therapy from 2004 to 2011. Bulky disease was defined as a measurable tumor mass >10cm in diameter or a mediastinal mass >1/3 of the chest diameter. Patients with primary mediastinal large B-cell lymphoma were excluded. The median age was 65years (20-78years) and the maximum tumor diameter was 11.5cm (10.0-17.0cm). Complete response and partial response were achieved in 14 patients each, while 1 patient had progressive disease. The 3-year overall survival (OS) rate and progression-free survival (PFS) rate were 66 and 56%, respectively. Findings on post-treatment positron emission tomography-computed tomography (PET-CT) were significantly associated with OS (34% for patients with abnormal uptake vs. 75% for those without, P=0.014), and were also associated with PFS (36 vs. 83%, respectively, P<0.001). Nine patients with a single site of abnormal uptake on PET-CT underwent radiotherapy and 5 of them subsequently relapsed. An initial bulky mass does not indicate a poor prognosis of DLBCL. However, the post-treatment PET-CT findings may have predictive value in DLBCL patients with a bulky mass.

CD68 staining correlates with the size of residual mass but not with survival in classical Hodgkin lymphoma

The prognostic role of CD68 tumor-associated macrophages in classic Hodgkin lymphoma (cHL) remains controversial. We stained diagnostic biopsies and scored for CD68 using the PGM1 antibody among 98 consecutive patients with cHL from our center followed over a median of 45 months for progression-free survival (PFS). Among 79 patients we assessed interim and post-treatment positron emission tomography-computed tomography (PET-CT). Residual mass (RM) size was based on the greatest diameter of the largest mass seen in post-treatment imaging, and percent reduction was calculated by comparing RM size with its greatest pretreatment diameter. We found a significant association between CD68 positivity and absolute size of initial disease mass (p = 0.014) and residual mass at the end of therapy (p = 0.006) but no association was observed with interim PET-CT results or PFS. Our findings suggest that macrophages may influence tumor size by altering the microenvironment. This study does not support a prognostic role of CD68 positivity in predicting survival.

Prognostic Significance Of Positron Emission Tomography-Computed Tomography In Patients With Marginal Zone Lymphoma

Background & Aims18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) scan has been increasingly used for initial staging and response evaluation in patients with lymphomas, and its clinical utility is well established in Hodgkin's lymphoma (HL) as well as in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). However, its role remains undetermined in marginal zone lymphomas (MZL), due to its relatively low FDG avidity as well as small numbers of patients in the Western countries although it is the most common type of indolent lymphoma in Korea. Thus, we aimed to assess the prognostic significance of PET-CT scan performed after first-line therapy in patients with MZL. Patients & MethodsWe retrospectively reviewed the medical records of a total of 194 patients with pathologically confirmed MZL in the Asan Medical Center between February 2003 and February 2011. Post-treatment FDG PET-CT scan was defined as which performed during the periods of 2 to 4 weeks after the completion of chemotherapy or 7 to 9 weeks after radiotherapy. Among them, we identified 32 patients with evaluable pretreatment, interim and post-treatment PET-CT scans who received chemotherapy. We investigated the prognostic significance of maximum standardized uptake value (SUVmax) at pretreatment PET-CT and metabolic complete response (mCR) at post-treatment PET-CT. The log-rank test was used to assess the correlation of event-free survival (EFS) and overall survival (OS) with baseline SUVmax or the presence of mCR. All categorical variables were analyzed using Chi-square test or Fisher's exact test. ResultsIn a total of analyzable 32 patients, histopathologic subtypes of them were as follow: Mucosa-associated lymphoid tissue (MALT) lymphoma (n=14, 43.8%), nodal MZL (n=17, 53.1%), and splenic MZL (n=1, 3.2%). The median SUVmax in pretreatment PET-CT was 5.3 (range, 1.3 – 18.8). There were no significant associations of SUVmax (cutoff: 5.3) at pretreatment PET-CT to mCR in both post-treatment and interim PET-CT scans (p =0.694 and p=0.723, respectively). However, high SUV group (SUVmax at baseline PET-CT >5.3) showed inferior 5-year EFS and OS to low SUV group (¡Â 5.3) with marginal statistical significicance (p=-0.072 and p=0.101, respectively). With a median follow-up duration of 41 months (range, 9 to 99 months), 5-year OS and EFS rate were 87.9% and 43.9%, respectively. 5-year EFS was significantly superior in patients who attained mCR at post-treatment PET-CT (p =0.010, 55.0% to 0%), and also in interim PET-CT (p=0.007, 70.6% to 13.1%). In addition, patients who attained early mCR showed significantly better 5-year EFS than patients of delayed and never mCR groups (p=0.011, 70.6% to 22.5%, and 0%). ConclusionIn our study cohort, patients with low SUVmax (¡Â 5.3) in pretreatment PET-CT showed strong trends of superior EFS and OS. More importantly, early attained mCR and mCR at post-treatment PET-CT were independent predictors of higher 5-year EFS rates. [Display omitted] [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Interim and Post-Treatment Positron Emission Tomography-Computed Tomography Scan Status Is Highly Predictive Of Outcome In Diffuse Large Cell Lymphoma Patients Treated With R-CHOP21

BackgroundTaking a step forward from the international prognostic index, attention is focused on the role of 18F-fluorodeoxyglucose positron-emission tomography-Computed Tomography scan (PET) as a tool for guidance in risk stratification in patients with diffuse large B-cell lymphoma (DLBCL). Here, we analyzed the predictive value of interim and post-treatment PET in patients with DLBCL. MethodsIn our retrospective study, we analyzed a homogeneous cohort of newly diagnosed DLBCL patients treated with R-CHOP21 who underwent PET scan at diagnosis, after three cycles of chemotherapy and at the end of treatment. For interim PET, images were interpreted by computing maximum standardized uptake value between PET performed at baseline and after three cycles of immuno-chemotherapy (¦¤SUVmax). The images of post-treatment PET were interpreted visually according to the International Harmonization Project criteria. The primary study endpoints were progression-free survival (PFS) and overall survival (OS). ResultsThirty-eight patients with DLBCL with PET data were identified. The median follow-up was 28 months. At interim PET evaluation, optimal cutoff to predict progression was 66% for ¦¤SUVmax. ¦¤SUVmax analysis (≥66% vs< 66%) identified patients with significantly different 2-year PFS (90.7% vs 38.9%; P =.000) and 2-year OS (95.5% vs 62%; P=.016) (Fig1). Post-treatment PET status (negative vs positive) was statistically significantly associated with 2-year PFS (91% vs 45.5%; P =.001) and 2-year OS (100% vs 72.7%; P =.012) (Fig2). [Display omitted] [Display omitted] ConclusionsThese data support the prognostic utility of PET in interim and post-treatment settings in patients with DLBCL treated with R-CHOP21. An interim PET scan after three cycles of treatment can effectively predict the outcome by using quantitative assessment of ¦¤SUVmax and allows clinicians to design a risk-adapted therapeutic strategy. A positive PET after the completion of therapy identifies a patient subset with an inferior PFS and OS. Disclosures:No relevant conflicts of interest to declare.

Prognostic Value of Positron Emission Tomography- Computed Tomography in Patients with Marginal Zone Lymphoma

AbstractAbstract 5084 Background & Aims18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) scan has been increasingly used for initial staging and response evaluation in patients with lymphomas, and its clinical utility is well established in diffuse large B-cell lymphoma as well as Hodgkin lymphoma. However, its role remains undetermined in marginal zone lymphomas (MZL), most common type of indolent lymphoma in Korea, due to its relatively low FDG avidity. Thus, we aimed to assess the prognostic significance of PET-CT scan in patients with MZL. Patients & methodsWe retrospectively reviewed the medical records of a total of 194 patients with pathologically confirmed MZL in the Asan Medical Center between February 2003 and February 2011. Post-treatment FDG PET-CT scan was defined as which performed during the periods of 2 to 4 weeks after the completion of induction chemotherapy or 7 to 9 weeks after radiotherapy. [a4] Among them, both baseline and post-treatment FDG PET-CT scans were performed in 64 patients. We investigated the prognostic significance of maximum standardized uptake value (SUVmax) at baseline PET-CT and metabolic complete response. Metabolic compete response (mCR) was defined as no pathologic FDG uptake at any site in post-treatment PET-CT scan. The log-rank test was used to assess the correlation of progression-free survival (PFS) and overall survival (OS) with baseline SUVmax or the presence of mCR. ResultsIn a total of analyzable 64 patients, histopathologic subtypes of them were as follow: extranodal marginal zone lymphoma (ENMZL=38, 59. 4%) including mucosa-associated lymphoid tissue (MALT) (n=35, 54. 7%) and bronchus-associated lymphoid tissue (BALT) (n=3, 4. 7%) lymphoma, nodal MZL (n=25, 39. 0%), splenic MZL (n=1, 1. 6%). The median SUVmax in baseline PET-CT was 4. 9 (range, 1. 3 – 18. 8). There were no significant associations of baseline SUVmax (cutoff: 5) to mCR at post-treatment PET-CT scan or survival outcomes. Patients group with high SUVmax (SUVmax >5. 0) showed mCR rate of 72. 7 %, and patients low SUVmax (SUVmax ° A′ 5) showed mCR rate of 67. 7%, respectively. (p=0. 786). With a median follow-up duration of 46 monthss (range, 13 to 109 months), 5-year OS and PFS rate were 91% and 71%, respectively. 5-year PFS rate (76% vs. 62%, p=0. 27) did not differ between complete metabolic responders and incomplete responders. However, complete metabolic responders showed higher 5 year OS rate compared with incomplete responders (93% vs. 86%, p=0. 43) although statistical significance was not secured. ConclusionIn the study cohort, baseline SUVmax was not a significant predictor of mCR, PFS nor OS. However, the patients achieved mCR at the end of induction treatment seemed to have superior survival rates than incomplete responders, which warrants further investigation. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Neck Dissection can be avoided after Sequential Chemoradiotherapy and Negative Post-treatment Positron Emission Tomography-Computed Tomography in N2 Head and Neck Squamous Cell Carcinoma

Aims This study assessed neck control in patients with N2 head and neck squamous cell carcinoma (HNSCC) treated with sequential chemoradiotherapy (SCRT) and the incidence of neck recurrence when neck dissection was withheld in those with negative post-treatment fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET). Materials and methods Thirty-four consecutive patients with N2 HNSCC who were treated with radical intent using SCRT were included. Twenty-seven patients received concomitant platinum-based chemotherapy with their radiotherapy. Nineteen patients were treated with intensity-modulated radiotherapy. PET-computed tomography (PET-CT) was obtained 3 months after the completion of radical radiotherapy. Neck dissection was carried out only in those with increased FDG uptake in the neck. Results The median follow-up was 39.1 months. One patient had increased FDG uptake in the neck post-treatment, which was false positive for malignancy. The remaining 33 patients were observed without neck dissection. No regional recurrence occurred. The negative predictive value (NPV) of post-treatment PET-CT was 100%. Conclusions Good disease control in the neck can be achieved in patients with N2 HNSCC with SCRT. Post-treatment PET-CT has a high NPV. Neck dissection can be avoided if post-treatment PET-CT is negative.

Phase II study of helical tomotherapy for oligometastatic colorectal cancer

BackgroundTo evaluate the efficacy and toxicity of helical tomotherapy in the treatment of oligometastatic colorectal cancer (CRC) patients who were not amenable for metastasectomy and/or (further) systemic treatment. Patients and methodsCRC patients with five or less metastases were enrolled. No limitations concerning dimension or localization of the metastases were imposed. Patients were treated with intensity-modulated and image-guided radiotherapy using helical tomotherapy, delivering a total dose of 40 Gy in fractions of 4 Gy. Positron emission tomography–computed tomography (PET-CT) was carried out at baseline and 3 months after the initiation of radiotherapy to evaluate the metabolic response rate according to PET Response Criteria in Solid Tumors (PERCIST) version 1.0. Side-effects were scored using National Cancer Institute Common Terminology Criteria for Adverse Events (NCI–CTC AE) version 3.0. ResultsTwenty-three patients were enrolled. A total of 52 metastases were treated. One patient (4%) experienced grade 3 vomiting; two patients (9%) grade 2 diarrhea and dysphagia, respectively. Twenty-two patients were evaluated by post-treatment PET-CT. Five (23%) and seven patients (32%) achieved a complete and partial metabolic response, respectively, resulting in an overall metabolic response rate of 55%. The actuarial 1-year local control, progression-free survival, and overall survival were 54%, 25% and 86%, respectively. ConclusionThe use of helical tomotherapy in oligometastatic CRC patients resulted in a promising metabolic response rate of 55%.

False-Positive Hypermetabolic Lesions on Post-Treatment PET-CT after Influenza Vaccination

We report a case of a 59-year-old man with testicular germ cell tumor who showed new hypermetabolic lesions at the left axillary lymph nodes on a post-treatment positron emission tomography-computed tomography (PET-CT) scan. The hypermetabolic lesions were found to be caused by an influenza vaccination 10 days prior to the PET-CT scan and disappeared without additional treatment. To date, he is alive with complete remission.

Prognostic Utility of Squamous Cell Carcinoma Antigen in Carcinoma of the Cervix: Association With Pre- and Posttreatment FDG-PET

Squamous cell carcinoma antigen (SCC Ag) is a serum biomarker for squamous cell carcinoma (SCC) of the cervix. We investigated the prognostic significance of SCC Ag levels before and at the completion of chemoradiotherapy and compared these levels with the results of pre- and posttreatment positron emission tomography/computed tomography (PET/CT) using [(18)F]fluorodeoxyglucose (FDG). The records of 63 women who underwent definitive chemoradiotherapy for SCC of the cervix were reviewed. SCC Ag levels were obtained before and at the completion of radiotherapy. Patients were divided into two groups on the basis of their pretreatment SCC Ag level (>30 ng/mL vs. ≤30 ng/mL). Pre- and posttreatment FDG-PET/CT characteristics and progression-free survival (PFS) were analyzed according to SCC Ag groups. Median follow-up was 12 months. Women with SCC Ag >30 ng/mL at diagnosis had more advanced lymph node disease on pretreatment FDG-PET/CT than those with SCC Ag ≤30 ng/mL (p = .002). Women whose SCC Ag normalized at the completion of chemoradiotherapy were more likely to have a complete metabolic response on their 3-month posttreatment FDG-PET/CT than those whose SCC Ag did not normalize (p = .006). The 2-year PFS was 73% for patients with a SCC Ag level ≤30 ng/mL at diagnosis compared with 0% for those with a SCC Ag level >30 ng/mL at diagnosis (p < .0001). The 2-year PFS was 62% for patients whose SCC Ag normalized at the completion of chemoradiotherapy compared with 0% for those whose SCC Ag did not normalize (p = .0004). Elevated SCC Ag at diagnosis and failure of the SCC Ag to normalize at the completion of treatment are associated with incomplete metabolic response and decreased PFS.

Radiation Pneumonitis: Local Dose Versus [ 18F]-Fluorodeoxyglucose Uptake Response in Irradiated Lung

To quantify the relationship between the local radiation dose received and the posttreatment positron emission tomography/computed tomography (PET/CT) [(18)F]2-fluoro-2-deoxyglucose (FDG) uptake in the lung. The data from 36 patients treated for esophageal cancer with thoracic radiotherapy who underwent restaging PET/CT imaging between 4 and 12 weeks after radiotherapy completion were evaluated. Their treatment planning CT was registered with the restaging PET/CT. Using histogram analysis, the voxel average FDG-PET uptake vs. radiation dose was obtained for each case. Hierarchical linear regression models for each patient were applied to study the variation in the linear trends between cases. Deviation of the dose-response curve from a linear model was tested. The median time between radiotherapy completion and FDG-PET imaging was 40 days (range, 26-70 days). The median of the mean standard uptake value in the lung that received 0-5 Gy was 0.63 (range, 0.36-1.27), 5-10 Gy was 0.77 (range, 0.40-1.35), 10-20 Gy was 0.80 (range, 0.40-1.72), and >20 Gy was 1.08 (range, 0.44-2.63). A hierarchical linear regression model of the radiation dose and normalized FDG uptake per case found an adequate fit with the linear model, and the addition of quadratic and logarithmic functions did not improve the fit. The 36 cases had a posterior mean of slopes range of 0.0048-0.069. The regional dose vs. radiation pneumonitis response was evaluated with FDG-PET/CT imaging. Statistical modeling found a linear relationship. The slope of this relationship varied over an order of magnitude, reflecting the range of the underlying biological response to radiation among the study population.