Refining the ITBCC tumor budding scoring system with a "zero-budding" category in colorectal cancer

Tumor budding scoring guidelines from the International Tumor Budding Consensus Conference (ITBCC) for colorectal cancer propose three groups: BD1 (0-4 buds/0.785mm2), BD2 (5-9 buds/0.785mm2), and BD3 (10 or more buds/0.785mm2). Here, we investigate whether a fourth scoring category, namely zero buds, may have additional clinical relevance. The number of tumor buds/0.785mm2 was scored in 959 cases. Those with zero tumor buds were considered BD0, while a new BD1 category of 1-4 buds was proposed. Associations of both scoring approaches with clinicopathological features were analyzed. Conventional ITBCC scoring showed expected associations with unfavorable histopathological prognostic factors. In total, 111/959 (11.6%) were BD0. A significant difference was found when BD0 was compared statistically to BD1 (1-4 buds) for pT, TNM, tumor grade, and lymphatic, venous, and perineural invasion (p<0.01, all). Tumors with BD0 occur relatively frequently and contribute additional information on tumor behavior. BD0 should be considered for subsequent ITBCC guidelines.