Feasibility of weekly cisplatin and radiotherapy for localized anal cancer – A Danish anal cancer group report

•Weekly Cisplatin for anal cancer is a safe treatment option in relation to outcome.•The overall hematological toxicity was low compared to historical data.•Weekly Cisplatin demonstrated an acceptable acute toxicity profile. Chemoradiotherapy (CRT) with flourouracil and mitomycin is the standard treatment for squamous cell carcinomas of the anus (SCCA), however the associated acute toxicity often hinders compliance. Although weekly cisplatin is a well-established treatment for other squamous cell carcinomas, it has not been explored in SCCA. To investigate if radiotherapy (RT) with weekly cisplatin is a feasible option for SCCA and to report the acute toxicity. Patients were treated with RT and weekly cisplatin 40 mg/m2 between 1998–2020. Retrospective data from medical records (n=65) and prospectively collected data from an observational study (n=51) comprising physician assessed toxicity (NCI-CTCAE 4.0), patient-reported outcomes (EORTC-QlQC30 + CR29) baseline, mid-therapy, end of treatment and 2–4 weeks post-treatment were included. Disease-free survival (DFS) and overall survival (OS) were estimated using the Kaplan-Meier method. We included 116 patients. T-stages were T1:4%, T2: 71%, T3: 17%, T4: 8% and 47% has N+ disease. RT doses were 53.75–64 Gy/45–51.2 Gy and the mean cumulative dose of cisplatin was 307.5 mg. The median overall treatment time was 43 days. Within 6 months after CRT 88.9 % had complete response. The median follow-up time was 4.5 years and 5-year DFS and OS were 77% (95%CI 68.7;84.5%) and 86.4% (95%CI 78.3;91.7%), respectively. Hospitalization occured in 20% with 2.6% being admitted due to febrile neutropenia. Hematological toxicity was low with 13.7% grade 3 and 3.9% grade 4. Anal pain, skin, gastrointestinal and urogenital toxicity were mild. RT and weekly cisplatin for SCCA showed good outcome results and an acceptable acute toxicity profile.