Oncologic Outcome After Preoperative Chemoradiotherapy in Patients With Pathologic T0 (ypT0) Rectal Cancer

BACKGROUND: Little is known about the oncologic outcomes of patients with ypT0 rectal cancer after preoperative chemoradiotherapy. OBJECTIVE: To evaluate the clinicopathologic characteristics and oncologic outcomes of patients with ypT0 rectal cancer after preoperative chemoradiotherapy and curative radical surgery. DESIGN AND SETTINGS: This was a retrospective review of factors influencing outcome of patients treated with preoperative chemoradiotherapy for rectal cancer at a tertiary care university medical center in Seoul, Korea between 2000 and 2008. PATIENTS: A total of 830 rectal cancer patients underwent surgery after preoperative chemoradiotherapy. Patients were included in the study if they had a pretreatment clinical classification of T3-4 or N+ (or T2N0 and preoperative chemoradiotherapy for sphincter preservation) and if they were classified on pathologic examination as ypT0 after preoperative CRT and curative radical surgery. Patients were classified as. MAIN OUTCOME MEASURES: Overall survival and disease-free survival were evaluated in relation to ypT0N0 or ypT0N1-2 status and other factors that might influence outcome. RESULTS: Of 91 patients included in the study, 54 (59.3%) were men; the mean patient age was 55 (SD, 11) years, and mean follow-up duration was 44 (SD, 23) months. Surgical procedures included low anterior resection in 68 patients, abdominoperineal resection in 21, and intersphincteric resection in 2. Mean tumor distance from the anal verge was 4.7 (SD, 1.8) cm. Of the 91 patients, 85 were classified as ypT0N0 and 6 as ypT0N1-2. No patient experienced local recurrence. A total of 11 patients (12.1%) had distant metastases, after a mean 11.1 months, including 7 (8.2%) with ypT0N0 and 4 (66.7%) with ypT0N1-2 tumors. One patient with ypT0N0 and 2 patients with ypT0N1-2 tumors died of metastasis. In patients classified as ypT0N0, the 5-year disease free survival and overall survival rates were 82.3% and 89.2%, respectively. Multivariate analysis showed that ypN1-2 status (p = 0.001) was a significant independent risk factor for recurrence (decreased 5-year disease-free survival), but no factor was associated with 5-year overall survival. LIMITATIONS: The study is limited by its retrospective nature. CONCLUSION: Oncologic outcomes in patients with ypT0N0 rectal cancer were excellent. The presence of residual cancer cells in mesorectal lymph nodes represents a risk factor for distant metastasis.