Radiation therapy alone is an adequate treatment for some patients with rectal cancer, according to a study published in a recent issue of the International Journal of Radiation Oncology, Biology, Physics (54:142-149, 2002).
The most common treatment for rectal cancer, surgery, is sometimes combined with radiation therapy to improve outcome. This study is the first of long-term local control and survival in patients treated with radiation therapy alone, and the results suggest that this is a suitable treatment for patients who are not candidates for surgery.
Between 1986 and 1998, 63 patients were entered into the pilot study. Eligibility criteria included T2-3, N0-1, M0 adenocarcinoma of the middle or lower rectum involving less than two-thirds of the circumference. Radiation therapy began with contact x-rays, followed by external-beam radiation therapy with a concomitant boost. After a 4- to 6-week interval, an iridium implant delivered a completion dose to the tumor. No chemotherapy was administered.
The median age of patients was 72 years. Of the 63 enrolled patients, 41 had T2 and 22 had T3 tumors. The mean distance of the tumor from the anal verge was 3.6 cm. All patients completed treatment according to the protocol, with the exception of seven who did not receive brachytherapy. With a median follow-up of 54 months, the primary local tumor control rate was 63%; after salvage surgery, the ultimate pelvic control rate was 73% (46 of 63). The 5-year overall survival rate was 64.4% , and for 42 patients aged less than 80 years, it was 79%, with 10 patients alive at 10 or more years.
No severe toxicity was seen, and although proctitis developed in most patients, it did not require an interruption in treatment. Late rectal bleeding occurred in 24 patients, but only one required a blood transfusion. Good anorectal function was maintained in 92% of living patients. The T stage was a strong prognostic factor, with a 5-year overall survival rate of 84% and 53% for T2 and T3 lesions, respectively, in patients under age 80.