Treatment of anal cancer with chemotherapy and intensity-modulated radiation therapy (IMRT) may be as effective as treatment with conventional radiation and chemotherapy but with fewer side effects. These findings were presented at the eighth annual Gastrointestinal Cancers Symposium.

Treatment of anal cancer that has not spread (metastasized) beyond the anus often involves chemotherapy and radiation therapy. Though this approach is associated with a high rate of disease-free survival, it is also associated with significant side effects. Conventional radiation uses a large radiation field, which may damage healthy tissues surrounding the cancer. Researchers are thus interested in finding alternative approaches to radiation that produce fewer side effects.

Intensity-modulated radiation therapy is a newer approach to radiation therapy that allows for more precise delivery of radiation to cancer cells while sparing healthy surrounding tissue. In studies of patients with breast, head and neck, and prostate cancers, IMRT has resulted in fewer side effects than conventionally delivered radiation.

To evaluate IMRT for the treatment of anal cancer, researchers with the Radiation Therapy Oncology Group (RTOG) conducted a Phase II study. Fifty-two patients with Stage II and III anal cancer were treated with IMRT. Outcomes were compared with findings from another RTOG trial, which used conventionally delivered radiation. The following results were reported at a median follow-up of 26.7 months:

• Two-year disease-free survival was 77% for IMRT compared with 75% for conventional radiation.
• Overall survival was 86% for IMRT compared with 91% for conventional radiation.
• Patients receiving IMRT experienced fewer skin and gastrointestinal side effects than those receiving conventional radiation.

These findings suggest that treatment of anal cancer with IMRT and chemotherapy produces similar survival to conventional radiation and chemotherapy, with fewer side effects.

Reference: Kachnic LA, Winter KA, R. J. Myerson RJ, et al. Two-year outcomes of RTOG 0529: A phase II evaluation of dose-painted IMRT in combination with 5-fluorouracil and mitomycin-C for the reduction of acute morbidity in carcinoma of the anal canal. Presented at the eighth annual Gastrointestinal Cancers Symposium in San Francisco, CA, January 20-22, 2011. Abstract 368.

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