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Natural Course Following Failure After Definitive Chemoradiation Therapy in HPV-Related and HPV-Unrelated Oropharyngeal Cancer
Volume 93 Number 3S Supplement 2015 95.5% and fe- 4.5%. All received 70 Gy to gross disease, and 98% (43) received concurrent chemotherapy. Of the 44 patients, 70.5% (31) were p16+ve, 20.5% (9) were p16-ve, and 9.1% (4) had unknown p16 status. Twenty-five (56.8%) had <10 pack-year history (PYH), and 43.2% (19) >10 PYH. Nodal status was as follows; N1 11% (nZ4), N2a 5% (nZ2), N2b 55% (nZ24), N2c 25% (nZ11), and N3 5% (nZ2). Nodal volumes were measured on CBCTs from treatment day 1, 10, 20, and 35. Nodal decrease (ND) was determined based on percent shrinkage from day 1 volume. Results: At a median follow-up of 17 months (2-31), the 2-year actuarial estimates of disease-free survival (DFS), local control (LC), regional control (RC), distant metastasis (DM), and overall survival (OS) were 87%, 94%, 92%, 89%, and 92% respectively. ND at days 10 or 35 did not correlate with outcomes, however, ND at day 20 (D20) and smoking status did. Pts with ND above the median decrease at D20 (40%) had improved 2year RC (100% vs 78.4%, PZ.03), and trended toward improved 2-year DFS (95.5% vs 72.7%, PZ.06), LC (100% vs 85%, PZ.08), and OS (100% vs 81.0%, PZ.11), compared to those with D20 ND <40%. Similarly, smoking status <10 PYH correlated with improved 2-year RC (100 vs 77%, PZ.02) and OS (100% vs 66%, PZ.003) with a trend to improved 2-year DFS (100% vs 79%, PZ.08) and LC (100% vs 84%, PZ.07) compared to those with >10 PYH. Among smokers, a ND at D20 >40% vs <40% had 2-year RC of 100% vs 49.4% (PZ.04). Two-year DM rates were higher in >10 PYH smokers (30% vs 0%, PZ.01) and p16 -ve (29% vs 4%, PZ.01) pts compared to <10 PYH and p16+ pts, respectively. Among p16+ve patients, a ND at D20 >40% vs <40% had 2year LC and RC of 100% vs 77.9% (PZ.05). Interestingly, pts with an increase in nodal volume between day 1 and 10 (4) all achieved RC, LC, and were without evidence of DM. Conclusion: ND of >40% by treatment day 20 is associated with improved RC, with a trend to improved DFS and LC. Smoking history was strongly associated with poorer RC and OS. P16-ve and smokers had higher rates of DM. All pts with <10 PYH achieved RC. The prognostic benefit for RC of midtreatment ND appeared to be confined to smokers with >10 PYH. This patient subset can potentially be identified during treatment and targeted for treatment intensification strategies to improve locoregional outcomes. An early increase in nodal size occurred in 10% and did not adversely affect outcomes. Author Disclosure: R. Stewart: None. K. Hu: Active member; ASTRO, New York Head and Neck Society. Z. Li: None. B. Culliney: None. M. Persky: None. A. Jacobson: None. M. Urken: None. T. Tran: None. S. Schantz: None. L.B. Harrison: None.
2754 Retrospective Analysis of Diminished Narcotic Dependency and Weight Loss With Prophylactic Gabapentin Use in Patients Undergoing Radiation Therapy for Oropharyngeal Cancer T. Dong,1 G.C. Jones,2 D. Scoble,3 and G.K. Bajaj3; 1Howard University College of Medicine, Washington, DC, 2National Cancer Institute, Bethesda, MD, 3Inova Comprehensive Cancer and Research Institute, Falls Church, VA Purpose/Objective(s): Pain and weight loss are common side effects of radiation therapy (RT) for head and neck cancer. Narcotic pain medication (NPM) is commonly used, but often results in incomplete pain control and is associated with its own side effects. Single-institution retrospective reports have provided evidence that prophylactic gabapentin (PG) may reduce the need for NPM in patients undergoing RT, however the ideal dosing schedule is unknown. The purpose of this study was to evaluate whether the use of 300 mg 3 times daily (TID) of PG in a community oncology center will result in reduced need for NPM or reduced weight loss (WL) in patients undergoing RT with or without chemotherapy (CT) for oropharyngeal (OPX) cancer. Materials/Methods: We performed a retrospective chart review of all patients treated with RT for OPX cancer in our clinic over the last 2
Poster Viewing Session E303 years. From these data, we stratified patients by the use of PG and compared the amount of NPM, the time to initiation of NPM, and the amount of WL between patients who did and did not receive PG. Twotailed t-tests were used to determine significance with a for significance set at P.05. Results: Over the past 2 years, 54 patients with OPX cancer completed their prescribed RT course and at least 1 month of post-RT follow-up at our institution. Twenty-one patients received PG (300 mg TID) within the first 2 weeks of RT. Patients who received PG had less unintentional WL (9.8 vs 15.8 lbs, PZ.025) and initiated NPM later in their RT course (34.6 vs 22.3 days, P<.001). Patients who underwent induction CT initiated NPM earlier (21.0 vs 28.4 days, PZ.041). Although patients who received PG did take a lower morphine-equivalent of opioids at completion of RT (58.6 vs 72.3 mg), this was not significant. OPX subsite and p16 status did not influence the effect of PG. No adverse effects were attributed to PG. Conclusion: Patients who initiated 300 mg TID of PG within the first 2 weeks of RT for OPX cancer experienced less WL and a longer time to initiation of NPM compared to those that did not initiate PG. These differences held true across OPX subsites and p16 status and no adverse effects were attributed to PG. These data support continued exploration of PG use in this patient population. Our institution intends to explore the effect of higher PG dosing in future patients to elucidate potential doseresponse relationships. Author Disclosure: T. Dong: None. G.C. Jones: None. D. Scoble: None. G.K. Bajaj: None.
2755 Natural Course Following Failure After Definitive Chemoradiation Therapy in HPV-Related and HPV-Unrelated Oropharyngeal Cancer S. Rathod, S.H. Huang, J.H. Kim, S. Su, W. Xu, J. Waldron, A. Bayley, S. Bratman, J. Cho, M.E. Giuliani, A.J. Hope, J.G. Ringash, A. Hansen, D. Goldstein, L. Tong, B. Perez-Ordonez, I. Weinreb, and B. O’Sullivan; Princess Margaret Cancer Centre / University of Toronto, Toronto, ON, Canada Purpose/Objective(s): To report patterns of first site of failure and outcomes after failure and to identity predictors of survival following failure in human papillomavirus-related (HPV+) and HPV-unrelated (HPV-) oropharyngeal cancer (OPC) treated with definitive radiation therapy (RT) or chemoradiation therapy (CRT). Materials/Methods: A prospectively assembled cohort of p16-confirmed OPC patients (pts) with documented disease relapse at local, regional, or distant sites following RT/CRT (RT dose 50 Gy) from 2000 to 2012 were included. Temporal pattern with frequency of site of first failure and outcome following failure were compared between HPV+ and HPV- cohorts. Overall survival (OS) after failure was estimated by Kaplan-Meier method and multivariate analysis (MVA) was performed to identify survival predictors. Results: A total of 249 OPC pts (136 HPV+ and 113 HPV-) with disease relapse following primary RT/CRT were identified. The most common site of first failure was locoregional (LRF) in the HPV- pts (70 [62%]), while distant metastases (DM) was most common in the HPV+ pts (84 [62%]). The interval from RT/CRT to DM was longer in HPV+ versus HPV- (16.7 vs 8.9 months, P<.01) but interval to LRF was similar (8.4 vs 6.8 months, PZ.80). First failure occurred within the first 2 years following RT/CRT in 90% HPV- versus 78% HPV+ cases. Median follow-up was 1.8 years. HPV+ pts had longer OS compared to the HPV(OS at 2 years: 32% vs 15%, P<.01). For the LRF alone subset, more HPV+ pts underwent salvage surgery (Sx) (30 of 52 [58%] vs 22 of 70 [31%], P.01). Salvage Sx recipients had higher OS (2-year rates: 43% vs 19%; P<.001) compared to those without salvage Sx. HPV+ pts had higher OS at 2 years compared to the HPVe pts (26% vs 11%, P<.01) for
E304 those without salvage Sx and marginally higher in those with salvage Sx (52% vs 30%, PZ.08). For the DM subset, HPV+ also had higher 2-year OS compared to the HPV- group (31% vs 19%, P<.01). On MVA, HPV+ status (hazard ratio [HR] 0.7, PZ.03), >20 smoking pack-years (HR 1.9, P<.01), and salvage Sx intervention (HR 0.4, P<.01) were the survival predictors. Conclusion: This study confirms a differing natural course following disease failure in HPV+ and HPV- OPC. A longer survival in HPV+ pts is observed in almost all subsets compared to their HPV- counterparts. In HPV+ pts, delayed distant failures are a feature with 22% DM presenting after 2 years of follow-up. This study has implications on surveillance strategies and highlights the importance of long-term surveillance in HPV+ pts. HPV status, smoking pack-years, and surgical salvage intervention are independent predictors of survival after progression. Author Disclosure: S. Rathod: None. S. Huang: None. J. Kim: None. S. Su: None. W. Xu: None. J. Waldron: None. A. Bayley: None. S. Bratman: None. J. Cho: None. M.E. Giuliani: Travel Expenses; ELECTA. A.J. Hope: Travel Expenses; ELECTA. J.G. Ringash: None. A. Hansen: None. D. Goldstein: None. L. Tong: None. B. Perez-Ordonez: None. I. Weinreb: None. B. O’Sullivan: None.
International Journal of Radiation Oncology Biology Physics Poster Viewing Abstracts 2756; Table 1 Clinical vs. Pathological Involvement of the Neck Node Levels in 30 Surgical Cases Pathological node involvement Clinical node involvement Node negative Single level Multiple levels Total
II III without III with III
5 5 1 2 17 (7) 30 (7)
I
II
III
IV
V
0 0 0 1 0 1
0 5 0 2 12/1 (6/2) 19/1 (6/2)
0 0 1 0 14 (4/2) 15 (4/2)
0 0 0 0 11/2 11/2
0 0 0 0 2/1 2/1
Data in parentheses denote the contralateral positive levels. The numbers after the slash indicate clinically negative but pathologically positive levels.
Author Disclosure: A. Semba: None. R. Murakami: None. D. Murakami: None. R. Toya: None. T. Hirai: None. T. Saito: None. T. Matsuyama: None. T. Toyofuku: None. N. Oya: None.
2757 2756 Assessment of the Neck Node Levels in Patients With Hypopharyngeal Carcinoma A. Semba,1 R. Murakami,2 D. Murakami,2 R. Toya,1 T. Hirai,2 T. Saito,1 T. Matsuyama,1 T. Toyofuku,1 and N. Oya1; 1Kumamoto University Hospital, Kumamoto, Japan, 2Kumamoto University, Kumamoto, Japan Purpose/Objective(s): Although elective neck irradiation has been recommended in definitive radiation therapy (RT) for patients with hypopharyngeal carcinoma (HPC), there is continuing controversy regarding the clinical target volume (CTV). In 2013, the international consensus guidelines for the delineation of the neck node (N) levels were updated. The purpose of this study was to assess the metastatic involvement of the N levels taking into consideration the CTV for HPC patients. Materials/Methods: Between 2005 and 2012, 75 HPC patients underwent pretreatment radiological examinations. The clinical N (cN) stage was cN0 in 26, cN1 in 3, cN2a in 1, cN2b in 31, cN2c in 9, and cN3 in 5 patients. Of the 75 patients, 30 underwent surgery and then the pathological N (pN) findings were recorded at each N level. The other patients underwent definitive RT; upper neck and whole neck irradiation was performed in 10 and 35 patients, respectively. We retrospectively assessed cN and pN involvement of the N levels. On follow-up examinations for the RT patients, the initial sites of disease progression were classified as local, regional, and distant. Results: Based on the neck node levels, the incidence of cN involvement of the ipsilateral retropharyngeal and levels I to V was 3%, 1%, 57%, 48%, 29% and 1%, respectively. Similar distributions were observed in the contralateral positive necks. In 30 surgical cases, the pN involvement was 3%, 3%, 63%, 50%, 37%, and 7%, respectively. There were pN level IV involvements, contralateral pN involvements, and false negative cN levels in patients with cN involvement of multiple levels including the level III. During a median follow-up period of 48 months (range, 3-111 months), local, regional, and distant were observed in 3, 4, and 3 of 45 RT patients, respectively; there were no regional progressions out of the target volumes even in patients treated with upper neck irradiation. Conclusion: In HPC patients, N involvements are common in the ipsilateral levels II and III; these levels should be included in the CTV. However, it is uncertain whether the CTV routinely including the level IV and/or the contralateral neck appears advantages.
Cervical Lymph Node Calcification on Its Own Following Radiation Therapy Is Not Predictive for Neck Recurrence in Oropharyngeal Carcinoma S. Rathod, S.H. Huang, J. Waldron, J.H. Kim, E. Yu, L. Tong, A. Bayley, S. Bratman, J. Cho, M.E. Giuliani, A.J. Hope, J.G. Ringash, and B. O’Sullivan; Princess Margaret Cancer Centre / University of Toronto, Toronto, ON, Canada Purpose/Objective(s): Claims that lymph node calcification (calLN+) following radiation therapy (RT) is a putative adverse feature for residual neck disease in head and neck cancer are not readily supported with evidence. This study evaluates the frequency and prognostic significance of post-RT calLN+ in lymph node-positive (LN+) oropharyngeal cancer (OPC) following definitive RT with or without chemotherapy (CRT). Materials/Methods: A retrospective review of a prospectively assembled cohort of LN+ OPC treated with RT/CRT from 2003 to 2012 was conducted. Tumor human papillomavirus (HPV) status was ascertained by p16 staining. calLN+ was identified by review of all patients (pts) with contrast-enhanced computed tomography (CT) undertaken within 6 months following RT. Radiological details of calLN+ and adverse radiologic features (defined as extra capsular extension [ECE], necrosis, or conglomerate nodal mass[es]) were recorded. Each calLN+ pt was matched to 2 controls without lymph node calcification (calLNe) treated during the same study period (1:2 matched for T, N category, and p16 status). Regional control (RC) was calculated using Kaplan-Meier method and log-rank test for comparison between study (calLN+) and control (calLNe) cohorts. Multivariable analysis (MVA) identified predictors for RC. Results: calLN+ were present in 52 (5%) of 966 consecutive LN+ OPC pts, of whom 31 (60%), 10 (19%), 3 (6%) and 8 (15%) had 1, 2, 3 or 4 calLN+, respectively. Median calLN+ size was 1.3 cm (range: 0.5-4.1 cm). The frequency of calLN+ did not differ between p16-positive (p16+) and p16-negative (p16e) pts (37 of 615 [6%] vs 12 of 192 [6%], PZ.90). The matched control cohort of 104 calLN- pts had similar demographic and clinical features compared to the study population. Post-RT neck dissection was performed in 9 of 52 (17%) calLN+ vs 13 of 104 (13%) calLNe pts (PZ.41). Adverse radiological features were present in 8 of 52 (15%) calLN+ vs 12 of 104 (12%) calLNe pts, respectively (PZ.49). Regional failure manifested in 7 of 52 (13%) calLN+ pts, 5 with residual nodal disease (all had adverse radiological features) while 2 failed subsequently. The remaining 42 calLN+ cases without adverse radiological features did not experience regional failure until the last follow-up. At the
2754 Retrospective Analysis of Diminished Narcotic Dependency and Weight Loss With Prophylactic Gabapentin Use in Patients Undergoing Radiation Therapy for Oropharyngeal Cancer T. Dong,1 G.C. Jones,2 D. Scoble,3 and G.K. Bajaj3; 1Howard University College of Medicine, Washington, DC, 2National Cancer Institute, Bethesda, MD, 3Inova Comprehensive Cancer and Research Institute, Falls Church, VA Purpose/Objective(s): Pain and weight loss are common side effects of radiation therapy (RT) for head and neck cancer. Narcotic pain medication (NPM) is commonly used, but often results in incomplete pain control and is associated with its own side effects. Single-institution retrospective reports have provided evidence that prophylactic gabapentin (PG) may reduce the need for NPM in patients undergoing RT, however the ideal dosing schedule is unknown. The purpose of this study was to evaluate whether the use of 300 mg 3 times daily (TID) of PG in a community oncology center will result in reduced need for NPM or reduced weight loss (WL) in patients undergoing RT with or without chemotherapy (CT) for oropharyngeal (OPX) cancer. Materials/Methods: We performed a retrospective chart review of all patients treated with RT for OPX cancer in our clinic over the last 2
Poster Viewing Session E303 years. From these data, we stratified patients by the use of PG and compared the amount of NPM, the time to initiation of NPM, and the amount of WL between patients who did and did not receive PG. Twotailed t-tests were used to determine significance with a for significance set at P.05. Results: Over the past 2 years, 54 patients with OPX cancer completed their prescribed RT course and at least 1 month of post-RT follow-up at our institution. Twenty-one patients received PG (300 mg TID) within the first 2 weeks of RT. Patients who received PG had less unintentional WL (9.8 vs 15.8 lbs, PZ.025) and initiated NPM later in their RT course (34.6 vs 22.3 days, P<.001). Patients who underwent induction CT initiated NPM earlier (21.0 vs 28.4 days, PZ.041). Although patients who received PG did take a lower morphine-equivalent of opioids at completion of RT (58.6 vs 72.3 mg), this was not significant. OPX subsite and p16 status did not influence the effect of PG. No adverse effects were attributed to PG. Conclusion: Patients who initiated 300 mg TID of PG within the first 2 weeks of RT for OPX cancer experienced less WL and a longer time to initiation of NPM compared to those that did not initiate PG. These differences held true across OPX subsites and p16 status and no adverse effects were attributed to PG. These data support continued exploration of PG use in this patient population. Our institution intends to explore the effect of higher PG dosing in future patients to elucidate potential doseresponse relationships. Author Disclosure: T. Dong: None. G.C. Jones: None. D. Scoble: None. G.K. Bajaj: None.
2755 Natural Course Following Failure After Definitive Chemoradiation Therapy in HPV-Related and HPV-Unrelated Oropharyngeal Cancer S. Rathod, S.H. Huang, J.H. Kim, S. Su, W. Xu, J. Waldron, A. Bayley, S. Bratman, J. Cho, M.E. Giuliani, A.J. Hope, J.G. Ringash, A. Hansen, D. Goldstein, L. Tong, B. Perez-Ordonez, I. Weinreb, and B. O’Sullivan; Princess Margaret Cancer Centre / University of Toronto, Toronto, ON, Canada Purpose/Objective(s): To report patterns of first site of failure and outcomes after failure and to identity predictors of survival following failure in human papillomavirus-related (HPV+) and HPV-unrelated (HPV-) oropharyngeal cancer (OPC) treated with definitive radiation therapy (RT) or chemoradiation therapy (CRT). Materials/Methods: A prospectively assembled cohort of p16-confirmed OPC patients (pts) with documented disease relapse at local, regional, or distant sites following RT/CRT (RT dose 50 Gy) from 2000 to 2012 were included. Temporal pattern with frequency of site of first failure and outcome following failure were compared between HPV+ and HPV- cohorts. Overall survival (OS) after failure was estimated by Kaplan-Meier method and multivariate analysis (MVA) was performed to identify survival predictors. Results: A total of 249 OPC pts (136 HPV+ and 113 HPV-) with disease relapse following primary RT/CRT were identified. The most common site of first failure was locoregional (LRF) in the HPV- pts (70 [62%]), while distant metastases (DM) was most common in the HPV+ pts (84 [62%]). The interval from RT/CRT to DM was longer in HPV+ versus HPV- (16.7 vs 8.9 months, P<.01) but interval to LRF was similar (8.4 vs 6.8 months, PZ.80). First failure occurred within the first 2 years following RT/CRT in 90% HPV- versus 78% HPV+ cases. Median follow-up was 1.8 years. HPV+ pts had longer OS compared to the HPV(OS at 2 years: 32% vs 15%, P<.01). For the LRF alone subset, more HPV+ pts underwent salvage surgery (Sx) (30 of 52 [58%] vs 22 of 70 [31%], P.01). Salvage Sx recipients had higher OS (2-year rates: 43% vs 19%; P<.001) compared to those without salvage Sx. HPV+ pts had higher OS at 2 years compared to the HPVe pts (26% vs 11%, P<.01) for
E304 those without salvage Sx and marginally higher in those with salvage Sx (52% vs 30%, PZ.08). For the DM subset, HPV+ also had higher 2-year OS compared to the HPV- group (31% vs 19%, P<.01). On MVA, HPV+ status (hazard ratio [HR] 0.7, PZ.03), >20 smoking pack-years (HR 1.9, P<.01), and salvage Sx intervention (HR 0.4, P<.01) were the survival predictors. Conclusion: This study confirms a differing natural course following disease failure in HPV+ and HPV- OPC. A longer survival in HPV+ pts is observed in almost all subsets compared to their HPV- counterparts. In HPV+ pts, delayed distant failures are a feature with 22% DM presenting after 2 years of follow-up. This study has implications on surveillance strategies and highlights the importance of long-term surveillance in HPV+ pts. HPV status, smoking pack-years, and surgical salvage intervention are independent predictors of survival after progression. Author Disclosure: S. Rathod: None. S. Huang: None. J. Kim: None. S. Su: None. W. Xu: None. J. Waldron: None. A. Bayley: None. S. Bratman: None. J. Cho: None. M.E. Giuliani: Travel Expenses; ELECTA. A.J. Hope: Travel Expenses; ELECTA. J.G. Ringash: None. A. Hansen: None. D. Goldstein: None. L. Tong: None. B. Perez-Ordonez: None. I. Weinreb: None. B. O’Sullivan: None.
International Journal of Radiation Oncology Biology Physics Poster Viewing Abstracts 2756; Table 1 Clinical vs. Pathological Involvement of the Neck Node Levels in 30 Surgical Cases Pathological node involvement Clinical node involvement Node negative Single level Multiple levels Total
II III without III with III
5 5 1 2 17 (7) 30 (7)
I
II
III
IV
V
0 0 0 1 0 1
0 5 0 2 12/1 (6/2) 19/1 (6/2)
0 0 1 0 14 (4/2) 15 (4/2)
0 0 0 0 11/2 11/2
0 0 0 0 2/1 2/1
Data in parentheses denote the contralateral positive levels. The numbers after the slash indicate clinically negative but pathologically positive levels.
Author Disclosure: A. Semba: None. R. Murakami: None. D. Murakami: None. R. Toya: None. T. Hirai: None. T. Saito: None. T. Matsuyama: None. T. Toyofuku: None. N. Oya: None.
2757 2756 Assessment of the Neck Node Levels in Patients With Hypopharyngeal Carcinoma A. Semba,1 R. Murakami,2 D. Murakami,2 R. Toya,1 T. Hirai,2 T. Saito,1 T. Matsuyama,1 T. Toyofuku,1 and N. Oya1; 1Kumamoto University Hospital, Kumamoto, Japan, 2Kumamoto University, Kumamoto, Japan Purpose/Objective(s): Although elective neck irradiation has been recommended in definitive radiation therapy (RT) for patients with hypopharyngeal carcinoma (HPC), there is continuing controversy regarding the clinical target volume (CTV). In 2013, the international consensus guidelines for the delineation of the neck node (N) levels were updated. The purpose of this study was to assess the metastatic involvement of the N levels taking into consideration the CTV for HPC patients. Materials/Methods: Between 2005 and 2012, 75 HPC patients underwent pretreatment radiological examinations. The clinical N (cN) stage was cN0 in 26, cN1 in 3, cN2a in 1, cN2b in 31, cN2c in 9, and cN3 in 5 patients. Of the 75 patients, 30 underwent surgery and then the pathological N (pN) findings were recorded at each N level. The other patients underwent definitive RT; upper neck and whole neck irradiation was performed in 10 and 35 patients, respectively. We retrospectively assessed cN and pN involvement of the N levels. On follow-up examinations for the RT patients, the initial sites of disease progression were classified as local, regional, and distant. Results: Based on the neck node levels, the incidence of cN involvement of the ipsilateral retropharyngeal and levels I to V was 3%, 1%, 57%, 48%, 29% and 1%, respectively. Similar distributions were observed in the contralateral positive necks. In 30 surgical cases, the pN involvement was 3%, 3%, 63%, 50%, 37%, and 7%, respectively. There were pN level IV involvements, contralateral pN involvements, and false negative cN levels in patients with cN involvement of multiple levels including the level III. During a median follow-up period of 48 months (range, 3-111 months), local, regional, and distant were observed in 3, 4, and 3 of 45 RT patients, respectively; there were no regional progressions out of the target volumes even in patients treated with upper neck irradiation. Conclusion: In HPC patients, N involvements are common in the ipsilateral levels II and III; these levels should be included in the CTV. However, it is uncertain whether the CTV routinely including the level IV and/or the contralateral neck appears advantages.
Cervical Lymph Node Calcification on Its Own Following Radiation Therapy Is Not Predictive for Neck Recurrence in Oropharyngeal Carcinoma S. Rathod, S.H. Huang, J. Waldron, J.H. Kim, E. Yu, L. Tong, A. Bayley, S. Bratman, J. Cho, M.E. Giuliani, A.J. Hope, J.G. Ringash, and B. O’Sullivan; Princess Margaret Cancer Centre / University of Toronto, Toronto, ON, Canada Purpose/Objective(s): Claims that lymph node calcification (calLN+) following radiation therapy (RT) is a putative adverse feature for residual neck disease in head and neck cancer are not readily supported with evidence. This study evaluates the frequency and prognostic significance of post-RT calLN+ in lymph node-positive (LN+) oropharyngeal cancer (OPC) following definitive RT with or without chemotherapy (CRT). Materials/Methods: A retrospective review of a prospectively assembled cohort of LN+ OPC treated with RT/CRT from 2003 to 2012 was conducted. Tumor human papillomavirus (HPV) status was ascertained by p16 staining. calLN+ was identified by review of all patients (pts) with contrast-enhanced computed tomography (CT) undertaken within 6 months following RT. Radiological details of calLN+ and adverse radiologic features (defined as extra capsular extension [ECE], necrosis, or conglomerate nodal mass[es]) were recorded. Each calLN+ pt was matched to 2 controls without lymph node calcification (calLNe) treated during the same study period (1:2 matched for T, N category, and p16 status). Regional control (RC) was calculated using Kaplan-Meier method and log-rank test for comparison between study (calLN+) and control (calLNe) cohorts. Multivariable analysis (MVA) identified predictors for RC. Results: calLN+ were present in 52 (5%) of 966 consecutive LN+ OPC pts, of whom 31 (60%), 10 (19%), 3 (6%) and 8 (15%) had 1, 2, 3 or 4 calLN+, respectively. Median calLN+ size was 1.3 cm (range: 0.5-4.1 cm). The frequency of calLN+ did not differ between p16-positive (p16+) and p16-negative (p16e) pts (37 of 615 [6%] vs 12 of 192 [6%], PZ.90). The matched control cohort of 104 calLN- pts had similar demographic and clinical features compared to the study population. Post-RT neck dissection was performed in 9 of 52 (17%) calLN+ vs 13 of 104 (13%) calLNe pts (PZ.41). Adverse radiological features were present in 8 of 52 (15%) calLN+ vs 12 of 104 (12%) calLNe pts, respectively (PZ.49). Regional failure manifested in 7 of 52 (13%) calLN+ pts, 5 with residual nodal disease (all had adverse radiological features) while 2 failed subsequently. The remaining 42 calLN+ cases without adverse radiological features did not experience regional failure until the last follow-up. At the