Tumour budding is a predictor of lymph node metastasis in colorectal carcinoma

Abstract

Context: Tumour budding score (TBS) implies poor prognosis in colorectal cancer (CRC). A higher score is associated with a higher rate of lymph node metastasis. Therefore, it influences the treatment modality in Stage 2 and pT1 CRC. The International Tumour Budding consensus conference (ITBCC) proposed use of x20 objective for scoring which is not frequently available in Indian Laboratories. Tata Memorial Centre (TMC) has proposed score groups for x40 objective which could be more feasible for reporting in India. Aims: To establish the significance of reporting tumour budding routinely in CRC and assess the reproducibility of TMC proposed score groups for x40 objective. Methods: 4 Hematoxylin and Eosin stained sections from the tumour were studied in 32 CRC cases. TBS was defined as the single worst field with highest number of Tumour buds using the x40 objective and scored as low=0 to 1, intermediate=2 to 4 and high= more than equal to 5. TBS was compared with nodal metastasis. Results: TBS was low in 23 cases, intermediate in 6 cases and high in 3 cases. All 3 cases with high TBS showed nodal metastasis with 2 cases (66%) having nodal stage N2b. All 6 cases with intermediate TBS score also showed nodal metastasis. Of the 23 low TBS cases, 7 showed nodal metastasis with 5 cases having nodal stage N1a. Conclusions: TBS using x40 objective is a reproducible method and is associated with higher risk of lymph node metastasis. It should be incorporated in routine reporting of all CRC cases.