Proceedings of the 52nd Annual ASTRO Meeting S459

2572 Head and Neck Cancer (HNC) Patients Undergoing Primary Radiation with Intensity Modulated

Radiation Therapy (IMRT) Demonstrate Improved Overall Survival (OS) Compared to Those UndergoingConventional Radiation Therapy (CRT) in the SEER-Medicare Linked Database

J. B. Yu1,2, P. M. Soulos2, R. Sharma3, D. V. Makarov1,2, R. H. Decker1,2, B. D. Smith4, R. A. Desai1,5, L. D. Cramer2,

C. P. Gross1,2

1Yale School of Medicine, New Haven, CT, 2Cancer Outcomes Policy and Effectiveness Research (COPPER) Center at Yale,New Haven, CT, 3Yale School of Public Health, New Haven, CT, 4MDACC, Houston, TX, 5Department of Veterans AffairsConnecticut Healthcare System, West Haven, CT

Purpose/Objective(s): Compared to CRT, IMRT improves quality of life and salivary function for patients with HNC undergoingradiotherapy, but no randomized trial has shown a difference in OS. We used the NCI Surveillance, Epidemiology and End Results- Medicare linked database (SEER-Medicare) from 2002-2005 to analyze survival for patients over the age of 65 who receivedIMRT or CRT for HNC.

Materials/Methods: OS, cancer specific survival (CSS), and non-cancer specific survival (NCSS) were assessed among 2,231HNC patients with localized cancer of the oral cavity, nasal cavity, nasopharynx, hypopharynx, oropharynx, and salivary glands.Lip and larynx were excluded due to low rates of IMRT use (5.13% and 13.95%). Covariates included Elixhauser comorbidityscore, age, race, sex, anatomic site, presence of positive lymph nodes, localized vs. regional disease, urban vs. rural residence,and income quartile by census tract, and were tested using multivariable Cox proportional hazards analysis. We analyzed the entirecohort as well as 4 subgroups of patients based on type of radiation received (primary versus postoperative) and use of concurrentchemotherapy (CT): Prim RT (N = 549), Prim RT + CT (N = 548), Post-op RT (N = 838), Post-op RT + CT (N = 296).

Results: The two-year OS for the entire cohort was 55.7% [SE 1.3%]. Two-year OS was 41.7% [SE 2.5%] for Prim RT, 53.4% [SE2.7%] for Prim RT + CT, 64.6% [SE 2.0%] for Post-op RT, and 60.3% [SE 3.5%] for Post-op RT + CT. There were 638 deaths dueto cancer, 199 due to other causes, and 19 for unknown causes. Overall, patients who underwent IMRT vs. CRT had greater OS (2yr OS 60.3% [SE 2.4%] vs. 53.7% [SE 1.5%], HR 0.85 [SE 0.07] p = 0.042), but they did not differ in CSS (HR 0.87 [SE 0.08] p =0.14) or NCSS (HR 0.78 [SE 0.13] p = 0.15).Patients who had Prim RT using IMRT vs. CRT had a statistically significant improvement in OS (2 year OS 51.8% [SE 5.1%] vs.38.0% [SE 2.8%], HR 0.72 [SE 0.10] p = 0.025) and CSS (HR 0.69 [SE 0.07] p = 0.032), but no difference in NCSS (HR 0.75 [SE0.22] p = 0.32). Survival was equivalent for IMRT vs. CRT for the other three subgroups.

Conclusions: Compared to CRT, IMRT is associated with significantly greater OS and CSS, but not NCSS, only in patients whoundergo Prim RT. Because our analysis is retrospective, results might be influenced by selection bias. There are also factors notaccounted for such as hospital/provider characteristics (i.e. hospital volume, academic vs. community). We hypothesize that OSand CSS may be improved using IMRT for Prim RT due to better target coverage, fewer treatment breaks, and dose escalation.Further work should seek to validate these results in other cohorts.

Author Disclosure: J.B. Yu, RSNA R&E Foundation Resident Research Grant, B. Research Grant; P.M. Soulos, None; R. Sharma,None; D.V. Makarov, None; R.H. Decker, None; B.D. Smith, None; R.A. Desai, None; L.D. Cramer, None; C.P. Gross, None.

2573 Patterns of Failure after Intensity Modulated Radiation Therapy (IMRT) for Nasopharyngeal Cancer

S. S. Arif1, A. J. Bayley1, B. O’Sullivan1, B. J. Cummings1, S. Fung2, E. Yu3, S. L. Breen4, E. Chen5, J. N. Waldron1, J. J. Kim1

1Department of Radiation Oncology, Princess Margaret Hospital, University of Toronto, Toronto, ON, Canada, 2Department ofBiostatistics, Princess Margaret Hospital, University of Toronto, Toronto, ON, Canada, 3Department of Medical Imaging,Princess Margaret Hospital, University of Toronto, Toronto, ON, Canada, 4Department of Radiation Physics, PrincessMargaret Hospital, University of Toronto, Toronto, ON, Canada, 5Department of Medical Oncology, Princess MargaretHospital, University of Toronto, Toronto, ON, Canada

Purpose/Objective(s): To evaluate the dosimetry of recurrences after IMRT for nasopharynx cancer (NPC) patients (pts) and todescribe the failure patterns.

Materials/Methods: An ethics approved, retrospective study of NPC pts treated at our institute with curative IMRT between Jan 1,2003 and Dec 31, 2007 was undertaken. IMRT was planned using CadPlan or Pinnacle. CTV(s) were subject to peer review. PTVmargins were 5 mm. Local (LR) and nodal (NR) recurrences were contoured on the original planning CT scan after rigid registra-tion with the diagnostic CT/MR scan documenting recurrence. In-target (IF) (.95% of LR/NR within 95% isodose), marginal(MF) (.20% - # 95% of LR/NR within 95% isodose) or out-of-target (OF) (# 20% of LR/NR within 95% isodose) failureswere evaluated. Overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan-Meier method. Probabilityof local (LC), regional (RC), locoregional (LRC) and distant (DC) control were estimated using cumulative incidence functionconsidering death as the competing risk.

Results: One hundred sixty-nine pts were identified: M:F - 104:65; median age - 51 years (17-87); median follow-up - 3.53 years(0.43-6.43); stage I -17 (10 %), stage IIa - 2 (1%), stage IIb - 27 (16%), stage III- 56 (33%), stage IVa - 48 (28%), IVb - 19 (11%). T4(33%), N2 (46%) and WHO IIb (97/108 evaluable) were the most common presentations. Pinnacle was used for 129 (76%) andCadplan for 40 (24%) IMRT plans. Thirty-seven (22%) pts received radiotherapy (RT) alone and 132 (78%) pts received RTand chemotherapy. Intended RT dose was 70Gy/35f for 166 (98 %) pts. Two and 5-year LC - 96% and 93%, RC - 96% and94%, LRC - 92% and 88%, DC - 90% and 87%, OS - 96% and 89% and DFS - 84% and 76%, respectively. There were 21 LRand/or NR in 20 patients - 12/20 (60%) LR only, 7/20 (35%) NR only and 1/20 (5%) LR and NR. To date, 13 of 14 Pinnaclerecurrences were evaluated for dosimetry. PTV [gross disease dose] dosimetric analysis showed 10/13 (77%) IF, 3/13 (23%)MF and no OF. Of the 3 MF, 2/3 (66%) were also MF for PTV [microscopic dose]. All MF were LR at the skull base in T4pts. Most common site of 8 NR was level 2B in 4 (50%) pts. There was no NR in nodal regions treated to microscopic dose.

Conclusions: We report excellent 2 and 5-year local and regional control after IMRT for NPC with our current contouring practices andPTV margins. For pts planned using Pinnacle, most recurrences were in-target. Marginal recurrences occurred only at the primary siteand limiting dose to organs-at-risk near the skull base may have been a factor in these T4 pts. There were no out-of-target recurrences.

Author Disclosure: S.S. Arif, None; A.J. Bayley, None; B. O’Sullivan, None; B.J. Cummings, None; S. Fung, None; E. Yu, None;S.L. Breen, None; E. Chen, None; J.N. Waldron, None; J.J. Kim, None.