Purpose: To analyze the long-term result of patients presenting with T2-T3 rectal adenocarcinoma treated with curative intent by radiotherapy (RT) alone, using a combination of contact RT, external beam RT, and brachytherapy with an iridium implant. Patients were considered unsuitable for surgery because of the presence of severe comorbidity or because they did not consent to surgery and the possibility of a permanent stoma.
Methods and materials: Between 1986 and 1998, 63 patients (56 staged with endorectal ultrasonography) were entered into a pilot study. Patients had to have T2-T3, N0-N1, M0 adenocarcinoma of the middle or lower rectum involving less than two-thirds of the circumference. RT began with contact X-rays (80 Gy in 3 fractions for 21 days), followed by external beam RT (39 Gy in 13 fractions for 17 days) with a concomitant boost (4 Gy in 4 fractions). After a 4-6-week interval, an iridium implant delivered a completion dose of 20 Gy to the tumor. No chemotherapy was given.
Results: The median age of the patients was 72 years. Of the 63 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, except for 7 for whom brachytherapy was not performed. With a median follow-up time of 54 months, the primary local tumor control rate was 63%; after salvage surgery, the ultimate pelvic control was 73% (46 of 63). The 5-year overall survival rate was 64.4%, and for 42 patients aged <80 years, it was 78% with 10 patients alive and well at > or =10 years. No severe Grade 3-4 toxicity was seen. Acute proctitis was seen in most patients but did not require treatment interruption. Late rectal bleeding occurred in 24 patients. Only 1 required 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 <80 years old.
Conclusion: This is the first report of long-term local control and survival for ultrasound-staged T2-T3 rectal adenocarcinoma treated by RT alone, showing that high-dose irradiation to a small volume can provide a high therapeutic ratio for such tumors.