Posttreatment TNM staging is a prognostic indicator of survival and recurrence in tethered or fixed rectal carcinoma after preoperative chemotherapy and radiotherapy.

PURPOSE: To evaluate the prognostic value of the posttreatment TNM stage as a predictor of outcome in locally advanced rectal cancers treated with preoperative chemotherapy and radiotherapy.

METHODS AND MATERIALS: Between 1993 and 2000, 128 patients with tethered (103) or fixed (25) rectal cancers were treated with 50 Gy preoperative pelvic radiotherapy and two cycles of concurrent 5-fluorouracil infusion (20 mg/kg/d) and leucovorin (200 mg/m(2)/d) chemotherapy on Days 1-4 and 22-25 and a single bolus mitomycin C injection (8 mg/m(2)) on Day 1. Of the 128 patients, 111 had Stage T3 and 17 Stage T4 according to the rectal ultrasound or CT findings and clinical evaluation. All 128 patients underwent surgery 8 weeks after chemoradiotherapy. Postoperatively, the disease stage was determined according to the surgical and pathologic findings using the American Joint Committee on Cancer TNM staging system.

RESULTS: Of the 128 patients, 32 had postchemoradiotherapy (pCR) Stage 0 (T0N0M0), 37 pCR Stage I, 26 pCR Stage II, 28 pCR Stage III, and 5 pCR Stage IV disease. Of the 128 patients, 79 had pCR Stage T0-T2, 35 pCR Stage T3, and 14 pCR Stage T4. The rate of T stage downstaging was 66% (84 of 128). Of the 128 patients, 25% achieved a pathologic complete response, and 31 (24%) had positive nodal disease. Lymphovascular or perineural invasion was found in 13 patients (10%). The 5-year disease-specific survival rate was 97% for pCR Stage 0, 88% for pCR Stage I, 74% for pCR Stage II, 44% for pCR Stage III, and 0% for pCR Stage IV (p = 0.0000059). The 5-year relapse-free survival rate was 97% for pCR Stage 0, 80% for pCR Stage I, 72% for pCR Stage II, 42% for pCR Stage III, and 0% for pCR Stage IV (p < 0.000001). In univariate analysis, the pretreatment tumor status (fixed vs. tethered tumors), the pCR TNM stage, T stage downstaging, pathologic T4 tumors, node-positive disease after chemoradiotherapy, and lymphovascular or perineural invasion were statistically significant prognosticators of disease-specific survival and relapse-free survival. pCR Stage T4 disease was a strong predictor of local recurrence. The 5-year local control rate was 98% for pCR T0-T2, 89% for pCR T3, and 65% for pCR T4 disease (p = 0.00044). In multivariate analysis, the pCR TNM stage was the most statistically significant independent predictor of survival (p = 0.003) and relapse-free survival (p < 0.001).

CONCLUSION: For patients who underwent preoperative chemoradiotherapy for locally advanced rectal cancer, the pCR TNM stage was a strong prognosticator of recurrence and survival. It can be used to identify high-risk patients for additional postoperative therapy.