The presence of poorly differentiated clusters predicts survival in stage II colorectal cancer.

In stage II colorectal carcinoma (CRC), adjuvant chemotherapy is reserved to cases at high risk of adverse outcome. This study aims to investigate the prognostic value of tumor budding (TB) and poorly differentiated clusters (PDC) in this setting. In a cohort of 149 patients with surgically resected stage II CRC not undergoing neoadjuvant or adjuvant treatments, we assessed the prognostic value of several clinical-pathological variables, including PDC and TB, on cancer-specific survival (CSS). Rectal location, lymphovascular invasion, and a number of lymph nodes < 12 confirmed to be significant and independent predictors of shorter CSS. A total of 117 CRCs were graded as PDC-G1 (0-4 PDCs), 19 as PDC-G2 (5-9 PDCs), and 13 as PDC-G3 (> 9 PDCs). Ninety-eight cases had PDC absent. TB foci were found in 91 CRCs; 121 were classified Bd1, 16 were Bd2, and 12 were Bd3. PDC-G2/G3 was significantly prognostic of shorter CSS (P < 0.0001). Among PDC-G1 cases, the presence of PDC was significantly associated with reduced CSS (P < 0.0001). Moreover, in the whole 149 CRCs, it had higher sensitivity and specificity to identify high-risk patients, compared to PDC grade, and it was independently associated with shorter CSS at multivariate analysis. High TB grade (Bd3) was significantly associated with shorter CSS (P = 0.0001), but it lost prognostic value at multivariate analysis. These findings suggest that the presence of PDC in stage II CRCs might be added to the pool of high-risk factors, warranting the use of adjuvant chemotherapy.