Head and Neck Cancer

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MO_23_2457 - Outcomes and Prognostic Factors of Locally Recurrent Nasopharyngeal Carcinoma Receiving Salvage Re-irradiation in the IMRT Era

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Outcomes and Prognostic Factors of Locally Recurrent Nasopharyngeal Carcinoma Receiving Salvage Re-irradiation in the IMRT Era
P. C. Chan, K. W. A. Cheung, W. Y. A. Ng, and C. S. F. Wong; Department of Clinical Oncology, Tuen Mun Hospital, Hong Kong, Hong Kong

Purpose/Objective(s): To evaluate the outcomes and prognostic factors in locally recurrent NPC patients receiving salvage re-irradiation.

Materials/Methods: Patients with locally recurrent NPC receiving salvage re-RT, whose primary treatments were delivered using IMRT between 2004 and 2012 were retrospectively reviewed. 3-year survival rates were the primary outcomes. Prognostic factors were also identified using univariate and multivariate analyses.

Results: A total of 894 patients with newly diagnosed non-metastatic NPC were treated with IMRT between 2004 and 2012. Sixty patients (6.7%) developed subsequent local only failure, of which 24 (mean [range] age, 56.2 [25.4-71.9] years; 19 [79.2%] men) received salvage re-RT. The median time to local recurrence was 35.0 months (interquartile range, 19.9-43.8) and the median follow-up time after re-RT was 26.8 months (interquartile range, 10.0-55.5). Most had advanced stage disease, 58.3% rT4, 12.5% rT3, 20.8% rT2 and 8.3% rT1. Nineteen patients (79.2%) received salvage re-RT using IMRT while 5 (20.8%) received fractionated stereotactic radiotherapy. The median mean dose to high risk PTV converting to EQD2 using α/β ratio 10 was 65.0Gy (range, 51.6-74.6) and the median dose per fraction was 2.4Gy (range, 1.2-3.4). The median high risk PTV volume was 61.5cm3 (range, 22.1-207.9). Eighteen patients (75.0%) achieved complete remission (CR) as evidenced by either endoscopy, MRI or PET-CT after salvage re-RT. Eleven patients (45.8%) had subsequent local progression. Twelve patients (50.0%) died of disease and 6 (25.0%) died of treatment-related complications. The 3-year local failure-free survival (LFFS), regional failure-free survival, distant failure-free survival and disease-free survival were 51.8%, 81.7%, 88.8% and 43.2% respectively. The median overall survival (OS) was 29.1 months while the 3-year overall survival was 50.0%. The 3-year cancer-specific survival was 65.3%. In the univariate analyses, T4 disease on initial diagnosis (HR 2.65, P=0.04), ECOG performance status >/= 2 (HR 8.87, P=0.02), high risk PTV volume >/=90cm3 (HR 4.14, P=0.02) and non-CR after salvage re-RT (HR 4.17, P=0.01) were statistically significant negative prognostic factors for OS. While T4 disease on initial diagnosis (HR 4.21, P=0.03) and non-CR after salvage re-RT (HR 10.50, P<0.01) were statistically significant negative prognostic factors for LFFS. In the multivariate analyses, high risk PTV volume >/=90cm3 (HR 6.38, P<0.01) and non-CR after salvage re-RT (HR 6.08, P<0.01) remained independent negative prognostic factors for OS. Non-CR after salvage re-RT (HR 10.50, P<0.01) also continued to be the independent negative prognostic factor for LFFS.

Conclusion: The outcomes of locally recurrent NPC receiving salvage re-RT remain challenging in the era of IMRT. Achieving complete response after salvage re-RT is an independent prognostic factor for both LFFS and OS.

Author Disclosure: P. Chan: None. K. Cheung: None. W. Ng: None.

Po Chung Chan, MBBS, FRCR, FHKCR, FHKAM

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