Evaluation of prognostic factors after primary chemoradiotherapy of anal cancer: A multicenter study of the German Cancer Consortium- Radiation Oncology Group (DKTK-ROG)

Background and purpose: Prognosis after chemoradiotherapy (CRT) for anal squamous cell carcinoma
(ASCC) shows marked differences among patients according to TNM subgroups, however individualized
risk assessment tools to better stratify patients for treatment (de-) escalation or intensified follow-up are
lacking in ASCC.
Materials and methods: Patients’ data from eight sites of the German Cancer Consortium - Radiation
Oncology Group (DKTK-ROG), comprising a total of 605 patients with ASCC, treated with standard defini-
tive CRT with 5-FU/Mitomycin C or Capecitabine/Mitomycin C between 2004–2018, were used to evalu-
ate prognostic factors based on Cox regression models for disease-free survival (DFS). Evaluated variables
included age, gender, Karnofsky performance score (KPS), HIV-status, T-category, lymph node status and
laboratory parameters. Multivariate cox models were separately constructed for the whole cohort and
the subset of patients with early-stage (cT1-2 N0M0) tumors.
Results: After a median follow-up of 46 months, 3-year DFS for patients with early-stage ASCC was 84.9%,
and 67.1% for patients with locally-advanced disease (HR 2.4, p < 0.001). T-category (HR vs. T1: T2 2.02;
T3 2.11; T4 3.03), N-category (HR versus N0: 1.8 for N1-3), age (HR 1.02 per year), and KPS (HR 0.8 per
step) were significant predictors for DFS in multivariate analysis in the entire cohort. The model per-
formed with a C-index of 0.68. In cT1-2N0 patients, T-category (HR 2.14), HIV status (HR 2.57), age
(1.026 per year), KPS (HR 0.7 per step) and elevated platelets (HR 1.3 per 100/nl) were associated with
worse DFS (C-index of 0.7).
Conclusion: Classical clinicopathologic parameters like T-category, N-category, age and KPS remain to be
significant prognostic factors for DFS in patients treated with contemporary CRT for ASCC. HIV and plate-
lets were significantly associated with worse DFS in patients with early stage ASCC.