Adjuvant radiochemotherapy in high-risk rectal cancer results of a prospective non-randomized study

In 1990 the National Institutes of Health Consensus Conference recommended adjuvant combined therapy for patients with radically resected rectal cancer at high risk for relapse (ie, stage II-III). The purpose of our prospective non-randomized study was to verify the feasibility and effectiveness of postoperative radiochemotherapy in terms of improvement in disease-free and overall survival in this patient subgroup.

From January 1990 to October 1998, 191 consecutive patients with radically resected stage II-III rectal cancer were treated. A total of 159 patients with a 24-month follow-up were assessable for toxicity and survival. Anterior resection was performed in 129 (81%) and abdomino-perineal resection in 30 (19%) patients. Fifty-four (34%) stage II and 105 (66%) stage III patients entered the study. Within 45-60 days of surgery, all patients received 5-fluorouracil chemotherapy at the dose of 500 mg/m2 as an i.v. bolus on days 1-5, every 4 weeks, for 6 cycles. Chemotherapy cycles III and IV were administered at the same daily dose on radiotherapy days 1-3 and 29-31. Radiotherapy consisted of 45 Gy/25 fractions plus a boost dose of 5.4 Gy.

After a median follow-up of 57 months (range, 25-123), overall recurrent disease was reported in 58 (36%) patients: local, systemic, and both local and systemic relapses in 12 (8%), 37 (23%) and 9 (6%) cases, respectively. According to local extension, recurrence rates were 15% and 48% in stage II and III, respectively. Five-year overall and disease-free survival were 71% and 66%, respectively. Overall survival was 87% in stage II and 62% in stage III patients, and disease-free survival was 84% and 56% in stage II and III disease, respectively. According to univariate and multivariate analyses, significant prognostic factors for better tumor control were: stage (II vs III, P <0.001), the number of involved nodes (< or = 3 vs > 3, P <0.0001), and no extracapsular node invasion (P <0.0001). The recommended dose of the combined radiochemotherapy regimen was generally well tolerated. The incidence of any > or = grade 3 acute toxicity (according to the WHO scale) was 13% diarrhea, 11% proctitis, 5% perineal dermatitis and 4% myelosuppression. Four (3%) patients had radiotherapy-related severe late toxicity which required surgery.

The study provided recurrence rates and survival similar to other adjuvant radiochemotherapy regimens published in the literature. However, in view of the low 5-year survival rate recorded in stage III patients, a different approach should be investigated.