Gastrointestinal Cancer

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SU_4_2035 - HIV-Positive Anal Cancer Patients Treated with Definitive Chemoradiation: Factors Impacting Clinical Outcomes

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

HIV-Positive Anal Cancer Patients Treated with Definitive Chemoradiation: Factors Impacting Clinical Outcomes
N. T. Pfister, S. Tian, D. G. Tanenbaum, C. Escott, K. M. Xu, P. R. Patel, J. C. Landry, M. W. McDonald, and J. Y. Lin Jr; Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, GA

Purpose/Objective(s): Patients with anal squamous cell carcinoma and human Immunodeficiency Virus (HIV) have been reported in some series to have worse outcomes with concurrent chemoradiation therapy (CRT) compared to non-HIV patients. We evaluated our experience treating HIV positive patients with anal cancer to assess patient and treatment-related factors related to disease outcomes following modern techniques of concurrent CRT.

Materials/Methods: A single institutional database of anal cancer patients treated with definitive-intent CRT was queried. Patients with HIV at time of CRT were selected for further analysis. Performance status, race, sex, stage, time from pathologic diagnosis to CRT initiation, antiretroviral therapy at time of CRT, radiotherapy technique, chemotherapy use, time to locoregional and distant failure, and cause of death were analyzed. Progression-free (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method, and p-values were calculated with the log-rank test.

Results: Between 2008-2017, 73 patients with HIV and anal cancer were treated with CRT. The majority were male (92%) and black (77%), and 97% had an ECOG performance status 0-1. Median age was 47 years [31-66]. Intensity-modulated radiotherapy was used exclusively in 67 patients and as a boost in 5 patients. 63 patients (86%) were receiving antiretroviral therapy prior to CRT. 13 patients were stage I, 20 stage II, and 40 stage III. Nodal status varied: 33 patients with N0, 4 with N1, 13 with N2, and 23 with N3 disease. 15 presented with T1 disease, 29 with T2, 25 with T3, and 4 with T4. All but 1 patient received 5-fluorouracil (5-FU)-based CRT: 29 with concurrent cisplatin and 39 with concurrent mitomycin C; 3 received 5-FU alone; 10 patients required dose reduction or missed part of a cycle. At median followup of 2.3 years [range <1 to 110 months], there were 13 patients with local (n=9) or distant (n=8) failure, or with both local and distant failure (n=4). Among 16 total deaths, 8 (11%) were attributable to anal cancer progression. Patients not receiving full dose concurrent chemotherapy had worse 12 month PFS (38% vs. 96%, p=.007) and OS (29% vs. 93%, p=0.003). Radiotherapy duration >50 days (≤50 or >50 days; median 43 vs. 55 days) had worse 12 month PFS (67% vs. 96%, p=.002) and OS (58% vs. 98%, p=0.013). Time from pathologic diagnosis to CRT initiation (≤50 or >50 days; median 42 vs. 91 days) was not associated with worse PFS (p=0.276) or OS (p=0.527). Antiretroviral therapy at time of CRT was not associated with worse PFS (p=.380) or OS (p=.600). Overall 12 and 24 month PFS (96% and 89%, respectively) and OS (94% and 88%, respectively) were excellent.

Conclusion: With median followup of over 2 years, we observed favorable disease control (PFS 89% at 2 years) despite a high percentage of stage III disease (55%). Lack of full-dose chemotherapy and radiotherapy duration >50 days were both associated with worse PFS and OS among this high-risk group of patients.

Author Disclosure: N.T. Pfister: None. S. Tian: None. D.G. Tanenbaum: None. C. Escott: None. P.R. Patel: None. J.C. Landry: None. M.W. McDonald: medical director; Emory Proton Therapy Center. J.Y. Lin: None.

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