Prognostic factors in stage T3NO rectal cancer - Do all patients require postoperative pelvic irradiation and chemotherapy?

PURPOSE: To further define the indications for postoperative pelvic irradia tion and chemotherapy, an analysis of the influence of extent of tumor inva sion into perirectal fat, lymphatic or venous vessel invasion, and tumor gr ade on the clinical course of patients with Stage T3N0 rectal cancer underg oing surgery was undertaken. METHODS: From 1968 to 1985, 117 patients with Stage T3N0 rectal cancer underwent resection with curative intent. No patie nt received neoadjuvant or adjuvant irradiation or chemotherapy. Surgical s pecimens were assessed for maximum depth of tumor invasion into perirectal fat, lymphatic or venous involvement, and tumor grade. After surgery the cl inical course of these patients was assessed for local control, distant met astases, and survival rate. RESULTS: For 25 patients with tumors exhibiting favorable histologic features (well-differentiated or moderately well-diff erentiated carcinomas invading less than 2 mm into perirectal fat, without lymphatic or venous vessel involvement), the ten-year actuarial rates of lo cal control and recurrence-free survival were 95 and 87 percent, respective ly. In contrast, the ten-year actuarial rates of local control and recurren ce-free survival were inferior (72 and 55 percent, respectively) for 88 pat ients with tumors exhibiting moderate to deep perirectal fat invasion, vess el involvement, or poor differentiation. CONCLUSIONS: In the design of futu re trials of rectal cancer, selection of patients with rectal cancer for po stoperative adjuvant therapy should be based not only on stage, but also on depth of invasion into the perirectal fat, vessel involvement, tumor grade , and integrity of the radial resection margin. For subsets of patients wit h Stage T3N0 rectal cancer, there may be little benefit to adjuvant therapy after surgery.