In a Canadian study reported in JAMA Oncology, Raphael et al found that interruption and noncompletion of definitive radiation and chemoradiation for patients with squamous cell anal carcinoma were common, and that failure to complete radiation and chemoradiation was associated with poorer outcomes.
The study involved data on all incident cases of squamous cell anal cancer treated with curative-intent radiation from 2007 to 2015 in Ontario. Treatment interruption was defined as more than 7 days between radiation fractions. Radiation completion was defined as receipt of 45 Gy or more and 25 fractions of radiation. Chemoradiation completion was defined as radiation completion and receipt of two or more doses of combination chemotherapy.
In total, 1,125 patients with stage I to III anal cancer were treated with curative-intent radiation and 1,002 patients (89%) received at least one dose of concurrent combination chemotherapy.
Treatment interruption occurred in 262 patients (23%) and noncompletion of radiation and chemoradiation occurred in 199 (18%) and 280 (25%), respectively.
In analysis adjusting for age, sex, stage, comorbidity score, and human immunodeficiency virus status, no factors were found to be significantly associated with treatment interruption.
Being older than age 70 vs younger than age 50 was associated with significantly reduced likelihood of completing radiation (relative risk [RR] = 0.86, P < .001) and chemoradiation (RR = 0.60, P < .01). Greater number of comorbidities was associated with reduced likelihood of completing chemoradiation (RR = 0.70, P = .02).
In adjusted analysis, failure to complete radiation was associated with increased risk of all-cause death (hazard ratio [HR] = 1.47, P < .001) and cancer-specific death (HR = 1.90, P < .01).
Failure to complete chemoradiation was associated with increased risk of salvage abdominoperineal resection (RR = 1.54, P = .04) and increased risk of all-cause death (HR = 1.54, P < .001), cancer-specific death (HR = 1.59, P <.01), and colostomy or death (HR = 1.80, P = .02). Treatment interruption was not significantly associated with any of these outcomes.
The investigators concluded, “Many patients undergoing curative-intent chemoradiation for anal cancer experienced treatment interruption or noncompletion. Quality improvement initiatives to optimize treatment continuity and completion are needed.”
Sunil V. Patel, MD, of the Division of Cancer Care and Epidemiology, Queen’s University Cancer Research Institute, Kingston, Ontario, is the corresponding author for the JAMA Oncology article.
Disclosure: The study was funded by Queen’s University Department of Surgery Research Fund. For full disclosures of the study authors, visit jamanetwork.com.