Résumé
To retrospectively assess the clinical outcome in anal cancer patients treated with split-course radiation therapy and boosted through external-beam radiation therapy (EBRT) or brachytherapy (BCT).
From January 2000 to December 2004, a selected group (162 patients) with invasive nonmetastatic anal squamous cell carcinoma was studied. Tumor staging reported was T1 = 31 patients (19%), T2 = 77 patients (48%), T3 = 42 patients (26%), and T4= 12 patients (7%). Lymph node status was N0–1 (86%) and N2–3 (14%). Patients underwent a first course of EBRT: mean dose 45.1 Gy (range, 39.5–50) followed by a boost: mean dose 17.9 Gy (range, 8–25) using EBRT (76 patients, 47%) or BCT (86 patients, 53%). All characteristics of patients and tumors were well balanced between the BCT and EBRT groups.
The mean overall treatment time (OTT) was 82 days (range, 45–143) and 67 days (range, 37–128) for the EBRT and BCT groups, respectively (
p < 0.001). The median follow-up was 62 months (range, 2–108). The 5-year cumulative rate of local recurrence (CRLR) was 21%. In the univariate analysis, the prognostic factors for CRLR were as follows: T stage (T1–2 = 15% vs. T3–4 = 36%,
p = 0.03), boost technique (BCT = 12% vs. EBRT = 33%,
p = 0.002) and OTT (OTT <80 days = 14%, OTT ≥80 days = 34%,
p = 0.005). In the multivariate analysis, BCT boost was the unique prognostic factor (hazard ratio = 0.62 (0.41–0.92). In the subgroup of patients with OTT <80 days, the 5-year CRLR was significantly increased with the BCT boost (BC = 9% vs. EBRT = 28%,
p = 0.03). In the case of OTT ≥80 days, the 5-year CRLR was not affected by the boost technique (BCT = 29% vs. EBRT = 38%,
p = 0.21).
In anal cancer, when OTT is <80 days, BCT boost is superior to EBRT boost for CRLR. These results suggest investigating the benefit of BCT boost in prospective trials.