Morphology and prognostic value of tumor budding in rectal cancer after neoadjuvant radiotherapy

Tumor budding is an acknowledged prognostic marker in colorectal cancer. This study was conducted to investigate the morphology and prognostic significance of budding in rectal cancer after neoadjuvant radiotherapy. Surgical specimens from 96 consecutive patients who underwent neoadjuvant radiotherapy and curative resection were retrieved to assess budding and other clinicopathologic factors. The morphology and prognostic significance of postirradiation tumor budding were closely associated with tumor regression grade. In the tumor regression grade 1 group, tumor budding presented as "false budding" and did not have a significant association with prognosis. In the tumor regression grade 2 and 3 groups, budding was observed surrounded by radiation-induced fibrosis and large populations of infiltrating inflammatory cells, and budding intensity was significantly associated with histologic differentiation, ypN stage, and lymphovascular invasion (P < .05). Moreover, the low-grade budding subgroup showed a significantly higher rate of 5-year disease-free survival than the high-grade budding subgroup (87.5% versus 55.6%, P < .0001). Multivariate analysis showed that pretreatment serum carcinoembyronic antigen, tumor regression grade, and tumor budding were the major independent factors affecting long-term disease-free survival. In conclusion, postirradiation budding has distinct morphology and prognostic significance in rectal cancer after neoadjuvant radiotherapy.