The document discusses using intensity-modulated radiation therapy (IMRT) for the treatment of anal cancer. Dosimetric studies and small clinical trials show that IMRT reduces radiation dosing and toxicity to normal tissues compared to conventional radiation therapy, without decreasing treatment effectiveness or local cancer control. Larger clinical trials are still needed to further evaluate IMRT for anal cancer and detect possible small variations in outcomes. The Radiation Therapy Oncology Group is currently conducting a phase II trial to further evaluate dose-painted IMRT for anal cancer.