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Recurrence Patterns of Locally Advanced Head and Neck Squamous Cell Carcinoma Patients after 3D Conformal Radiotherapy with or without Chemotherapy
I. J. Radiation Oncology d Biology d Physics
S414
Volume 75, Number 3, Supplement, 2009
Results: The mean volumes of GTV-P contoured on CT, PET, PET+CT and MRI were 22.81cm3, 24.49cm3, 30.30cm3 and 26.81cm3, respectively. The mean volumes of GTV-N on CT, PET, PET+CT and MRI were 20.37cm3, 22.50cm3, 29.09cm3 and 26.22cm3, respectively. Taking MRI as the gold standard, Pearson correlation revealed a strong correlation in the localization of GTV-P by different imaging tools: (1) MRI vs. CT (r = 0.990, p = 0.000), (2) MRI vs. PET (r = 0.964, p = 0.000) and (3) MRI vs. PET+CT (r = 0.979, p = 0.000). Subgroup analysis stratified into advanced (T3 & T4, AJCC 2002) and early T-Stage (T1, T2a & T2b, AJCC 2002) showed that high degrees of correlation for GTV-P were still maintained (MR vs. CT, r = 0.992, p = 0.000; MR vs. PET, r = 0.969, p = 0.000; and MR vs. PET+CT, r = 0.979, p 0.000). A high degree of correlation was also noted in GTV-N (MRI vs. CT, r = 0.976, p 0.000), (MRI vs. PET, r = 0.909, p = 0.000) and (MR vs. PET+CT, r = 0.975, p = 0.000). The minimum concentration of FDG in localizing both GTV-P (from 6800 to 7300 Bq/mL) and GTV-N (from 6800 to 7500 Bq/mL) were highly consistent and reproducible. Conclusions: The incorporation of PET scan into the standard MRI and CT co-registration is definitely feasible and helpful in tumor localization. Future efforts should be made to derive the most appropriate algorithm in contouring the GTV on PET images. Author Disclosure: V. Lee, None; D.L.W. Kwong, None; P.L. Khong, None; D.T.T. Chua, None; S.C.Y. Ng, None; G.K.W. Wong, None; K.S. Chan, None; T.W. Leung, None; G.K.H. Au, None.
2518
Failure Patterns of Early Stage NPC with Lymph Nodes Metastasis after Definitive Radiotherapy
G. Yunsheng, G. Zhu, X. He, H. Ying, L. Kong, Y. Wu, C. Hu Fudan University Cancer Hospital, Shanghai, China Purpose/Objective(s): To investigate failure patterns of early stage nasopharyngeal carcinoma with lymph node metastasis treated by radiation alone in single institution. Materials/Methods: From Jan. 2000 to Dec. 2003, 357 patients with early stage nasopharyngeal carcinoma existing lymph node metastasis staged according to the AJCC (1997) cancer staging classification were retrospectively analyzed. All patients had pathologically confirmed World Health Organization (WHO) type III NPC. The T classification was T1:117(32.8%), T2:240(67.2%). All patients with N1classification were included. Patients were immobilized in the supine position with a thermoplastic mask, followed by conventional simulation and planning. Radiation therapy were delivered by opposed lateral fields followed pre-auricular fields or only pre-auricular fields, including the primary disease, para-nasopharyngeal space, skull base, pterygopalatine fossa, posterior one-third to half of the nasal cavity and maxillary sinus, and whole neck lymph drainage region. The dose was 64–74 Gy, 1.8– 2.0 Gy per fraction over 6.5–7.5 weeks to the primary tumor with 60Co or 6MV X-rays, and 64–70 Gy to neck lymph node, 50–56 Gy to lower risk neck areas. Intracavitary high-dose brachytherapy to a dose of 6–8 Gy in 1 or 2 weekly fractions were used to treat limited residual lesions measured less than 1 cm .All patients received no chemotherapy before loco-regional failure or distant metastasis. Results: The median follow- up time was 55 months (range, 1–88 months). To the end of the follow-up, there are 14 cases experienced neck recurrence, 33 patients developed local recurrence in the primary area. In addition, 47 patients developed distant metastasis. A total of 68 cases died. 37 patients died from distant metastasis, 28 died from progression of local or regional disease after recurrence, and the causes of death of 6 additional cases were unknown. The 5-year overall survival rate(OS) was 78.6%. 5-year relapse-free survival rate(L-FFR), distant metastasis-free survival rate(D-FFR) and disease-free survival rate(DFS) were 86.7%, 85.6% and 74.7%, respectively. Both uni- and multivariate analyses demonstrated that T classification was the significant prognostic factor for predicting OS, DFS and D-FFR. While local or regional recurrence was affected by dose of irradiation. Conclusions: For early stage nasopharyngeal carcinoma with lymph node metastasis, distant metastasis is main failure pattern followed by local recurrence and regional relapse. T classification was the significant prognostic factor for predicting OS, DFS and D-FFR. Radiation combined with chemotherapy may reduce distant metastasis rate and improve overall survival and localregional control. Author Disclosure: G. Yunsheng, None; G. Zhu, None; X. He, None; H. Ying, None; L. Kong, None; Y. Wu, None; C. Hu, None.
2519
Recurrence Patterns of Locally Advanced Head and Neck Squamous Cell Carcinoma Patients after 3D Conformal Radiotherapy with or without Chemotherapy
D. Oksuz1, B. Carey1, S. Wilson1, M. Senocak2, K. Dyker1, C. Coyle1, M. Sen1 St. James’s Institute of Oncology, Leeds, United Kingdom, 2I.U.Cerrahpasa Medical Faculty Department of Biostatistics, Istanbul, Turkey
1
Purpose/Objective(s): To establish recurrence patterns among locally advanced head and neck non-nasopharyngeal squamous cell carcinoma (HNSCC) patients treated with radical radiotherapy or chemoradiotherapy (chemoXRT) and to correlate the sites of locoregional recurrence with radiotherapy volumes. Materials/Methods: One hundred and fifty one locally advanced HNSCC patients were treated between January 2004 and December 2005 using three-dimensional (3D) conformal CT-planned external beam radiotherapy. The median age was 59 years (range,34–89 years). Thirty-five (23.2%) patients had Stage III disease, 116 patients had Stage IV A/B. One hundred and fifteen patients were treated with chemoXRT and 36 (23.8%) patients were treated with radical radiotherapy alone. All patient images were reviewed to identify the precise site of locoregional recurrence. Local and regional recurrences were compared to previous radiotherapy doses and target volumes with the aid of radiologist and dosimetrist. The recurrences were classified as 1) "in-field," in which 95% or more of the recurrence volume (V(recur)) was within the 95% isodose; 2) "marginal," in which 20% to 95% of V(recur) was within the 95% isodose; or 3) "outside," in which less than 20% of V(recur) was within the 95% isodose. Univariate and multivariate analyses were performed according to covariates properties. Results: The median follow-up all patients was 38 months (range,3–62 months). One hundred twenty five of 151 (82.8%) patients achieved complete response after their radical treatment. Among the patients who had achieved a complete response 20 patients
Proceedings of the 51st Annual ASTRO Meeting recurred locally and/or regionally and 16 patients developed distant metastasis. The 3-year local and regional control rates were 86.8%, 89.5%, respectively in complete responders. For the entire cohort of 151 patients, the 3-year cause specific survival rate was 66.8%. Of the 14 local recurrences 12 were in-field recurrences. Of the 11 regional failures 6 were in field recurrences. On univariate analysis age, tumor subsite and T-Stage were significant prognostic factors for progression-free and cause specific survival. On multivariate analysis T-Stage was found as a significant prognostic factor affecting both progression-free and cause specific survival. Conclusions: Most of the local-regional recurrences are within the PTV suggesting that local regional failure is not related to geographical miss but might relate to intrinsic radio-resistance or associated factors (e.g., hypoxia). By improving loco-regional control, the pattern of recurrences is changing compared with historical series, with metastatic relapse a more common occurrence. As translational research may aid outcome prediction we plan to explore this further. Author Disclosure: D. Oksuz, None; B. Carey, None; S. Wilson, None; M. Senocak, None; K. Dyker, None; C. Coyle, None; M. Sen, None.
2520
Combined-modality Treatment of Sinonasal Undifferentiated Carcinoma of the Head and Neck
M. Little, E. Lin, A. Eisbruch, M. Feng University of Michigan Health System, Ann Arbor, MI Purpose/Objective(s): Sinonasal undifferentiated carcinoma (SNUC) is an uncommon malignancy for which the optimal management strategy is unknown. We investigated the outcome of various combined-modality treatment approaches for SNUC at a single institution. Materials/Methods: The records of 15 patients with SNUC treated with curative intent at the University of Michigan between 1994 and 2008 were retrospectively analyzed. The tumor stage at presentation was T2 in 2 patients, T3 in 2 patients, T4 in 11 patients, and N1 in 2 patients. Treatment consisted of surgical resection and adjuvant concurrent chemoradiotherapy (chemoRT) in 8 patients, concurrent chemoRT alone in 6 patients, or sequential chemoRT in 1 patient. No differences were observed with respect to tumor stage between the treatment groups. The median adjuvant radiation dose was 60 Gy (range, 58–64.6), and the median definitive radiation dose was 70 Gy (range, 64–70). Of the 13 patients without evidence of regional nodal disease, 6 received elective neck irradiation. Gross total resection was achieved in all but 1 patient undergoing surgery as initial therapy. Median follow-up was 24 months (range, 2–147). Outcomes were calculated using the Kaplan-Meier method and compared using log–rank tests. Results: The 3-year outcome estimates are as follows: local control, 61%; distant metastasis-free survival, 66%; cause-specific survival, 66%; and overall survival, 62%. Patients undergoing definitive chemoRT had an improved cause-specific survival relative to those undergoing resection followed by adjuvant chemoRT (100 vs. 58% at 2 years, p = 0.01), with a trend toward improved overall survival (86 vs. 58% at 2 years, p = 0.09). There was no significant difference in local control, which was 67% for definitive chemoRT patients and 56% for surgery followed by adjuvant chemoRT patients (p = 0.57). No differences in local control or survival were found with respect to age, gender, T-Stage, intracranial involvement, or orbital invasion. Of the 7 total recurrences, 1 was local only, 2 were distant only, and 3 patients relapsed with both local and distant disease. There was only 1 neck failure, which occurred outside the radiation field in a patient with N1 disease. This patient also had simultaneous evidence of local and distant recurrence. No isolated neck recurrences were observed. There was 1 treatment-related death in a patient who developed febrile neutropenia 1 week after completion of definitive chemoRT. Conclusions: This is the largest series of patients with SNUC treated definitively with chemoRT. In contrast to the published literature where surgery is a mainstay of therapy, this suggests treatment results for SNUC with definitive chemoRT are equivalent, if not superior, to those of surgical resection followed by adjuvant chemoRT. Author Disclosure: M. Little, None; E. Lin, None; A. Eisbruch, None; M. Feng, None.
2521
Development of a Rodent Model to Study Flap Revascularization in Irradiated Tissue
P. C. Angelos, C. Bicquart, K. E. McCarn, S. S. Winn, T. Ghanem, D. S. Kaurin, J. M. Holland, M. K. Wax Oregon Health & Science University, Portland, OR Purpose/Objective(s): To develop a reproducible animal model to study the effects of radiation on flap revascularization. Materials/Methods: Following IACUC review and approval, sixteen male Sprague-Dawley rats received either 23 or 40 Gy to their ventral abdominal walls. Radiation was delivered over five fractions with 6 MeV electrons and 1 cm bolus. After a recovery period, the animals underwent ventral fasciocutaneous flap with subsequent pedicle ligation at 10 days. Percentage (area) of flap viability was recorded as a measure of flap revascularization 5 days after pedicle ligation. An additional sixteen rats received 40 Gy and underwent pedicle ligation at 8 or 14 days to evaluate the effect of time to pedicle ligation on flap viability. Results: Histologic sectioning of flap tissue after 40 Gy revealed loss of adnexal structures and dermal sclerosis consistent with radiation effect. Rats receiving 40 Gy had a significantly lower average percentage of flap viability (57%) than animals receiving 23 Gy (91%) Decreasing the time interval from 40 Gy until pedicle ligation lead to significant decreases in flap viability. Animals with 14 day intervals had flap viability rates of 73%; 10 day intervals 57%, and 8 day intervals 39% (ANOVA between all four groups, p \ 0.001). Conclusions: We have successfully created an animal model to evaluate the effects of radiation on flap revascularization and viability. This model will allow for the study of novel therapies to improve wound healing, flap revascularization, and flap viability in irradiated tissues. Author Disclosure: P.C. Angelos, None; C. Bicquart, None; K.E. McCarn, None; S.S. Winn, None; T. Ghanem, None; D.S. Kaurin, None; J.M. Holland, None; M.K. Wax, None.
S415
S414
Volume 75, Number 3, Supplement, 2009
Results: The mean volumes of GTV-P contoured on CT, PET, PET+CT and MRI were 22.81cm3, 24.49cm3, 30.30cm3 and 26.81cm3, respectively. The mean volumes of GTV-N on CT, PET, PET+CT and MRI were 20.37cm3, 22.50cm3, 29.09cm3 and 26.22cm3, respectively. Taking MRI as the gold standard, Pearson correlation revealed a strong correlation in the localization of GTV-P by different imaging tools: (1) MRI vs. CT (r = 0.990, p = 0.000), (2) MRI vs. PET (r = 0.964, p = 0.000) and (3) MRI vs. PET+CT (r = 0.979, p = 0.000). Subgroup analysis stratified into advanced (T3 & T4, AJCC 2002) and early T-Stage (T1, T2a & T2b, AJCC 2002) showed that high degrees of correlation for GTV-P were still maintained (MR vs. CT, r = 0.992, p = 0.000; MR vs. PET, r = 0.969, p = 0.000; and MR vs. PET+CT, r = 0.979, p 0.000). A high degree of correlation was also noted in GTV-N (MRI vs. CT, r = 0.976, p 0.000), (MRI vs. PET, r = 0.909, p = 0.000) and (MR vs. PET+CT, r = 0.975, p = 0.000). The minimum concentration of FDG in localizing both GTV-P (from 6800 to 7300 Bq/mL) and GTV-N (from 6800 to 7500 Bq/mL) were highly consistent and reproducible. Conclusions: The incorporation of PET scan into the standard MRI and CT co-registration is definitely feasible and helpful in tumor localization. Future efforts should be made to derive the most appropriate algorithm in contouring the GTV on PET images. Author Disclosure: V. Lee, None; D.L.W. Kwong, None; P.L. Khong, None; D.T.T. Chua, None; S.C.Y. Ng, None; G.K.W. Wong, None; K.S. Chan, None; T.W. Leung, None; G.K.H. Au, None.
2518
Failure Patterns of Early Stage NPC with Lymph Nodes Metastasis after Definitive Radiotherapy
G. Yunsheng, G. Zhu, X. He, H. Ying, L. Kong, Y. Wu, C. Hu Fudan University Cancer Hospital, Shanghai, China Purpose/Objective(s): To investigate failure patterns of early stage nasopharyngeal carcinoma with lymph node metastasis treated by radiation alone in single institution. Materials/Methods: From Jan. 2000 to Dec. 2003, 357 patients with early stage nasopharyngeal carcinoma existing lymph node metastasis staged according to the AJCC (1997) cancer staging classification were retrospectively analyzed. All patients had pathologically confirmed World Health Organization (WHO) type III NPC. The T classification was T1:117(32.8%), T2:240(67.2%). All patients with N1classification were included. Patients were immobilized in the supine position with a thermoplastic mask, followed by conventional simulation and planning. Radiation therapy were delivered by opposed lateral fields followed pre-auricular fields or only pre-auricular fields, including the primary disease, para-nasopharyngeal space, skull base, pterygopalatine fossa, posterior one-third to half of the nasal cavity and maxillary sinus, and whole neck lymph drainage region. The dose was 64–74 Gy, 1.8– 2.0 Gy per fraction over 6.5–7.5 weeks to the primary tumor with 60Co or 6MV X-rays, and 64–70 Gy to neck lymph node, 50–56 Gy to lower risk neck areas. Intracavitary high-dose brachytherapy to a dose of 6–8 Gy in 1 or 2 weekly fractions were used to treat limited residual lesions measured less than 1 cm .All patients received no chemotherapy before loco-regional failure or distant metastasis. Results: The median follow- up time was 55 months (range, 1–88 months). To the end of the follow-up, there are 14 cases experienced neck recurrence, 33 patients developed local recurrence in the primary area. In addition, 47 patients developed distant metastasis. A total of 68 cases died. 37 patients died from distant metastasis, 28 died from progression of local or regional disease after recurrence, and the causes of death of 6 additional cases were unknown. The 5-year overall survival rate(OS) was 78.6%. 5-year relapse-free survival rate(L-FFR), distant metastasis-free survival rate(D-FFR) and disease-free survival rate(DFS) were 86.7%, 85.6% and 74.7%, respectively. Both uni- and multivariate analyses demonstrated that T classification was the significant prognostic factor for predicting OS, DFS and D-FFR. While local or regional recurrence was affected by dose of irradiation. Conclusions: For early stage nasopharyngeal carcinoma with lymph node metastasis, distant metastasis is main failure pattern followed by local recurrence and regional relapse. T classification was the significant prognostic factor for predicting OS, DFS and D-FFR. Radiation combined with chemotherapy may reduce distant metastasis rate and improve overall survival and localregional control. Author Disclosure: G. Yunsheng, None; G. Zhu, None; X. He, None; H. Ying, None; L. Kong, None; Y. Wu, None; C. Hu, None.
2519
Recurrence Patterns of Locally Advanced Head and Neck Squamous Cell Carcinoma Patients after 3D Conformal Radiotherapy with or without Chemotherapy
D. Oksuz1, B. Carey1, S. Wilson1, M. Senocak2, K. Dyker1, C. Coyle1, M. Sen1 St. James’s Institute of Oncology, Leeds, United Kingdom, 2I.U.Cerrahpasa Medical Faculty Department of Biostatistics, Istanbul, Turkey
1
Purpose/Objective(s): To establish recurrence patterns among locally advanced head and neck non-nasopharyngeal squamous cell carcinoma (HNSCC) patients treated with radical radiotherapy or chemoradiotherapy (chemoXRT) and to correlate the sites of locoregional recurrence with radiotherapy volumes. Materials/Methods: One hundred and fifty one locally advanced HNSCC patients were treated between January 2004 and December 2005 using three-dimensional (3D) conformal CT-planned external beam radiotherapy. The median age was 59 years (range,34–89 years). Thirty-five (23.2%) patients had Stage III disease, 116 patients had Stage IV A/B. One hundred and fifteen patients were treated with chemoXRT and 36 (23.8%) patients were treated with radical radiotherapy alone. All patient images were reviewed to identify the precise site of locoregional recurrence. Local and regional recurrences were compared to previous radiotherapy doses and target volumes with the aid of radiologist and dosimetrist. The recurrences were classified as 1) "in-field," in which 95% or more of the recurrence volume (V(recur)) was within the 95% isodose; 2) "marginal," in which 20% to 95% of V(recur) was within the 95% isodose; or 3) "outside," in which less than 20% of V(recur) was within the 95% isodose. Univariate and multivariate analyses were performed according to covariates properties. Results: The median follow-up all patients was 38 months (range,3–62 months). One hundred twenty five of 151 (82.8%) patients achieved complete response after their radical treatment. Among the patients who had achieved a complete response 20 patients
Proceedings of the 51st Annual ASTRO Meeting recurred locally and/or regionally and 16 patients developed distant metastasis. The 3-year local and regional control rates were 86.8%, 89.5%, respectively in complete responders. For the entire cohort of 151 patients, the 3-year cause specific survival rate was 66.8%. Of the 14 local recurrences 12 were in-field recurrences. Of the 11 regional failures 6 were in field recurrences. On univariate analysis age, tumor subsite and T-Stage were significant prognostic factors for progression-free and cause specific survival. On multivariate analysis T-Stage was found as a significant prognostic factor affecting both progression-free and cause specific survival. Conclusions: Most of the local-regional recurrences are within the PTV suggesting that local regional failure is not related to geographical miss but might relate to intrinsic radio-resistance or associated factors (e.g., hypoxia). By improving loco-regional control, the pattern of recurrences is changing compared with historical series, with metastatic relapse a more common occurrence. As translational research may aid outcome prediction we plan to explore this further. Author Disclosure: D. Oksuz, None; B. Carey, None; S. Wilson, None; M. Senocak, None; K. Dyker, None; C. Coyle, None; M. Sen, None.
2520
Combined-modality Treatment of Sinonasal Undifferentiated Carcinoma of the Head and Neck
M. Little, E. Lin, A. Eisbruch, M. Feng University of Michigan Health System, Ann Arbor, MI Purpose/Objective(s): Sinonasal undifferentiated carcinoma (SNUC) is an uncommon malignancy for which the optimal management strategy is unknown. We investigated the outcome of various combined-modality treatment approaches for SNUC at a single institution. Materials/Methods: The records of 15 patients with SNUC treated with curative intent at the University of Michigan between 1994 and 2008 were retrospectively analyzed. The tumor stage at presentation was T2 in 2 patients, T3 in 2 patients, T4 in 11 patients, and N1 in 2 patients. Treatment consisted of surgical resection and adjuvant concurrent chemoradiotherapy (chemoRT) in 8 patients, concurrent chemoRT alone in 6 patients, or sequential chemoRT in 1 patient. No differences were observed with respect to tumor stage between the treatment groups. The median adjuvant radiation dose was 60 Gy (range, 58–64.6), and the median definitive radiation dose was 70 Gy (range, 64–70). Of the 13 patients without evidence of regional nodal disease, 6 received elective neck irradiation. Gross total resection was achieved in all but 1 patient undergoing surgery as initial therapy. Median follow-up was 24 months (range, 2–147). Outcomes were calculated using the Kaplan-Meier method and compared using log–rank tests. Results: The 3-year outcome estimates are as follows: local control, 61%; distant metastasis-free survival, 66%; cause-specific survival, 66%; and overall survival, 62%. Patients undergoing definitive chemoRT had an improved cause-specific survival relative to those undergoing resection followed by adjuvant chemoRT (100 vs. 58% at 2 years, p = 0.01), with a trend toward improved overall survival (86 vs. 58% at 2 years, p = 0.09). There was no significant difference in local control, which was 67% for definitive chemoRT patients and 56% for surgery followed by adjuvant chemoRT patients (p = 0.57). No differences in local control or survival were found with respect to age, gender, T-Stage, intracranial involvement, or orbital invasion. Of the 7 total recurrences, 1 was local only, 2 were distant only, and 3 patients relapsed with both local and distant disease. There was only 1 neck failure, which occurred outside the radiation field in a patient with N1 disease. This patient also had simultaneous evidence of local and distant recurrence. No isolated neck recurrences were observed. There was 1 treatment-related death in a patient who developed febrile neutropenia 1 week after completion of definitive chemoRT. Conclusions: This is the largest series of patients with SNUC treated definitively with chemoRT. In contrast to the published literature where surgery is a mainstay of therapy, this suggests treatment results for SNUC with definitive chemoRT are equivalent, if not superior, to those of surgical resection followed by adjuvant chemoRT. Author Disclosure: M. Little, None; E. Lin, None; A. Eisbruch, None; M. Feng, None.
2521
Development of a Rodent Model to Study Flap Revascularization in Irradiated Tissue
P. C. Angelos, C. Bicquart, K. E. McCarn, S. S. Winn, T. Ghanem, D. S. Kaurin, J. M. Holland, M. K. Wax Oregon Health & Science University, Portland, OR Purpose/Objective(s): To develop a reproducible animal model to study the effects of radiation on flap revascularization. Materials/Methods: Following IACUC review and approval, sixteen male Sprague-Dawley rats received either 23 or 40 Gy to their ventral abdominal walls. Radiation was delivered over five fractions with 6 MeV electrons and 1 cm bolus. After a recovery period, the animals underwent ventral fasciocutaneous flap with subsequent pedicle ligation at 10 days. Percentage (area) of flap viability was recorded as a measure of flap revascularization 5 days after pedicle ligation. An additional sixteen rats received 40 Gy and underwent pedicle ligation at 8 or 14 days to evaluate the effect of time to pedicle ligation on flap viability. Results: Histologic sectioning of flap tissue after 40 Gy revealed loss of adnexal structures and dermal sclerosis consistent with radiation effect. Rats receiving 40 Gy had a significantly lower average percentage of flap viability (57%) than animals receiving 23 Gy (91%) Decreasing the time interval from 40 Gy until pedicle ligation lead to significant decreases in flap viability. Animals with 14 day intervals had flap viability rates of 73%; 10 day intervals 57%, and 8 day intervals 39% (ANOVA between all four groups, p \ 0.001). Conclusions: We have successfully created an animal model to evaluate the effects of radiation on flap revascularization and viability. This model will allow for the study of novel therapies to improve wound healing, flap revascularization, and flap viability in irradiated tissues. Author Disclosure: P.C. Angelos, None; C. Bicquart, None; K.E. McCarn, None; S.S. Winn, None; T. Ghanem, None; D.S. Kaurin, None; J.M. Holland, None; M.K. Wax, None.
S415