The Prognostic Value of Micropapillary Pattern in Colon Cancer and Its Role as a High-Risk Feature in Patients With Stage II Disease

BACKGROUND: The association of a micropapillary pattern with oncologic outcomes has not been fully studied in patients with colon cancer. OBJECTIVE: We evaluated the prognostic value of a micropapillary pattern, especially for patients with stage II colon cancer. DESIGN: A retrospective comparative cohort study using propensity score matching. SETTING: This study was conducted at a single tertiary center. PATIENTS: Patients with primary colon cancer undergoing curative resection from October 2013 to December 2017 were enrolled. Patients were grouped into micropapillary pattern positive or micropapillary pattern negative. MAIN OUTCOME MEASUREMENTS: Disease-free survival and overall survival. RESULTS: Of the eligible 2192 patients, 334 (15.2%) were with micropapillary pattern (+). After 1:2 propensity score matching, 668 patients with micropapillary pattern-negative status were selected. The micropapillary pattern-positive group showed significantly worse 3-year disease-free survival (77.6% vs 85.1%, p = 0.007). Three-year overall survival of micropapillary pattern-positive and micropapillary pattern-negative patients did not show a statistically significant difference (88.9% vs 90.4%, p = 0.480). In multivariable analysis, micropapillary pattern-positive was an independent risk factor for poor disease-free survival (HR 1.547, p = 0.008). In the subgroup analysis for 828 patients with stage II disease, 3-year disease-free survival deteriorated significantly in micropapillary pattern-positive patients (82.6% vs 93.0, p < 0.001). Three-year overall survival was 90.1% and 93.9% in patients positive and negative for micropapillary pattern, respectively (p = 0.082). In the multivariable analysis for patients with stage II disease, micropapillary pattern-positive status was an independent risk factor for poor disease-free survival (HR 2.003, p = 0.031). LIMITATIONS: Selection bias due to the retrospective nature of the study. CONCLUSIONS: Micropapillary pattern-positive status may serve as an independent prognostic factor for colon cancer, especially for patients with stage II disease.