Budding, tumor-infiltrating lymphocytes, gland formation: scoring leads to new prognostic groups in World Health Organization low-grade colorectal cancer with impact on survival.

Grading for colorectal carcinoma (CRC) is traditionally based on the percentage of gland formation. In recent years, high-grade CRC has become subject to more precise molecular grading strategies. Most, however, are low-grade cases according to the World Health Organization (WHO) with inhomogenous outcomes due to still insufficient characterization. On the other hand, budding and tumor-infiltrating lymphocytes have developed as interesting additive prognostic factors in CRC. Especially budding has been very well defined by the International Tumor Budding Consensus Conference recently. We analyzed a large collective of 576 WHO low-grade CRC cases, stages I to IV, diagnosed between 2005 and 2016 in terms of gland formation, budding, and tumor-infiltrating lymphocytes and developed a new, morphology-based risk score, taking into account each of the 3 parameters. For each parameter, 1 to 2 points were given, resulting in a sum score, dividing the CRC cases into a low-, an intermediate-, and a high-risk group. By our score, 179 (34.9%) of the cases were grouped as low risk, 241 (53.5) as intermediate risk, and 92 (35.5%) as high risk. The 3 groups differed significantly in pT, pN, and M as well as tumor stages, lymphatic vessel invasion, venous invasion, and overall survival (0.;P < .001 for low risk versus high risk, P = .038 for low versus intermediate risk, and P = .036 for intermediate versus high risk; log rank: median, 94.0 months [95% confidence interval {CI}, 74.9-113.1] for low risk; median, 63.0 months [95% CI, 44.0-82.0] for intermediate risk; and median, 40.0 months [95% CI, 23.4-56.7] for high risk) in Kaplan-Meier-analysis. Our proposed Bayreuth score enables separating the large group of WHO low-grade CRC cases into subgroups, which differ significantly in outcome.