Intensity-modulated radiation therapy (imrt) for anal cancer: Results from a multi-institutional retrospective cohort study.

Abstract

523 Background: This study was done to assess the toxicity and efficacy of IMRT for anal cancer in a multi-institutional setting. Methods: Records of 152 total patients (pts) were reviewed retrospectively. Data on disease control and toxicity were collected as well as pt and treatment characteristics. Acute (<6 months) and late (>=6 months) severe toxicity (grade >=3) were recorded at each institution. Four were excluded for either presence of metastatic disease (2) or stage TX (2). There was data for late toxicity on 120 pts. Results: T stage was T1 in 28, T2 in 79, T3 in 29 and T4 in 12 pts. N stage was N0 in 77, N1 in 40, N2 in 19 and N3 in 12 pts. The median age was 56 yrs and median follow-up was 26.8 months. Cumulative IMRT dose was 51.25 Gy (median) (range: 4.32-61.2 Gy) in a median of 28 fractions (2-34). Chemotherapy was given in all but 2 pts and the most common regimen was 5- fluorouracil plus mitomycin-C. The median total elapsed treatment time was 40 days. Local control at 3 yrs was 87% and was significantly worse for patients with T3-4 disease (79% vs 90% at 3 years; p=0.04). There was no correlation between dose and local control. Regional control, distant control and overall survival were 97%, 91%, and 87% at 3 yrs, respectively. Nodal status was associated with regional and distal control as well as overall survival (p<0.01 for each). The most common acute severe toxicity was hematologic (41%). Severe acute GI, skin or other toxicity was 11%, 20% and 1% respectively. There were two grade 5 toxicities (hematologic and GI). Severe late toxicity was limited to skin (1%) and GI (3%). Conclusions: IMRT resulted in excellent local control in this multi-institutional cohort of pts. Although T stage did predict for worse local control, most pts with T3-4 disease were controlled with IMRT. Nodal status predicts for regional and distal control as well as overall survival. Severe toxicity was acceptable with this technique.