Anal canal cancer: management of inguinal nodes and benefit of prophylactic inguinal irradiation (CORS-03 Study)

Abstract

Purpose: To evaluate the benefit of prophylactic inguinal irradiation (PII) in anal canal squamous cell carcinoma (ASCC).

Methods and materials: This retrospective study analyzed the outcome of 208 patients presenting with ASCC treated between 2000 and 2004 in four cancer centers of the south of France.

Results: The population study included 35 T1, 86 T2, 59 T3, 20 T4, and 8 T stage unknown patients. Twenty-seven patients presented with macroscopic inguinal node involvement. Of the 181 patients with uninvolved nodes at presentation, 75 received a PII to a total dose of 45-50 Gy (PII group) and 106 did not receive PII (no PII group). Compared with the no PII group, patients in the PII group were younger (60% vs. 41% of patients age <68 years, p = 0.01) and had larger tumor (T3-4 = 46% vs. 27% p = 0.01). The other characteristics were well balanced between the two groups. Median follow-up was 61 months. Fourteen patients in the no PII group vs. 1 patient in the PII group developed inguinal recurrence. The 5-year cumulative rate of inguinal recurrence (CRIR) was 2% and 16% in PII and no PII group respectively (p = 0.006). In the no PII group, the 5-year CRIR was 12% and 30% for T1-T2 and T3-T4 respectively (p = 0.02). Overall survival, disease-specific survival, and disease-free survival were similar between the two groups. In the PII group, no Grade >2 toxicity of the lower extremity was observed.

Conclusion: PII with a dose of 45 Gy is safe and highly efficient to prevent inguinal recurrence and should be recommended for all T3-4 tumors. For early-stage tumors, PII should also be discussed, because the 5-year inguinal recurrence risk remains substantial when omitting PII (about 10%).