Pathologic determinants of survival after resection of T3NO (Stage IIA) colorectal cancer: Proposal for a new prognostic model

PURPOSE: There is an increasing need for accurate prognostic stratification of patients with Stage 11 colorectal cancer to identify a subgroup of high-risk patients who may benefit from adjuvant therapies. This study was designed to evaluate the prognostic impact of a wide spectrum of pathologic parameters in a consecutive series of homogenously treated and well-characterized patients with Stage IIA (T3N0M0) colorectal cancer. METHODS: The study included 238 patients operated on by a single surgeon for Stage IIA colorectal tumors. The median postoperative follow-up was 110 (range, 96-120) months. At least 12 lymph nodes were harvested and examined in all the resection specimens. The prognostic value of 13 pathologic parameters, including lymph node occult disease (micro-metastases) detected by immunohistochemistry, was investigated. RESULTS: Multivariate analysis identified tumor growth pattern (expanding or infiltrating; P=0.01) and extent of tumor spread beyond muscularis propria (<= 5 mm or >5 mm; P = 0.04) as the only factors having independent prognostic value. The combination of these two easily determined parameters allowed us to identify two groups of patients at low risk or high risk of tumor recurrence. The eight-year survival rates were 83.3 and 53.4 percent for the two groups, respectively. The high-risk group comprised those patients with infiltrating tumors and extramural tumor spread > 5 mm. CONCLUSIONS: We propose a new and simple prognostic model to identify patients with high-risk Stage IIA colorectal cancer for whom adjuvant therapies may be justified and effective.