Purpose: To evaluate the feasibility of delivering conformal radiotherapy (RT) and concurrent chemotherapy without a mandatory break in patients with anal canal carcinoma.
Methods and materials: Thirty patients with T2-T4 tumors were treated with a combination of 54 Gy in 30 fractions and two cycles of 5-fluorouracil and mitomycin C. Dose-volume histograms were obtained for bone marrow, small bowel, and skin to compare the conventional technique using the Radiation Therapy Oncology Group standard with our conformal technique.
Results: The mean dose ratio of the conventional compared with the conformal technique for bone marrow, small bowel, and skin was, respectively, 2.1-2.7, 3.0, and 2.0, in favor of the conformal technique. All patients completed their treatment without a treatment break. An incidence of Grade 3 toxicity for bone marrow, bowel, and skin of 13.3%, 3.3%, and 20%, respectively, was observed. With a median follow-up of 33 months, a 4-year local recurrence-free survival rate of 91% was observed.
Conclusion: The results of this study have shown that conformal RT leads to a well-tolerated treatment. The treatment time is shortened to 6 weeks. A significant decrease in the acute toxicity rate suggests that by decreasing the "volume factor," conformal RT improves the therapeutic index in patients treated with combined chemotherapy and RT.