Relationship of Desmoplastic Reaction and Tumour Budding in Primary and Lung Metastatic Lesions of Colorectal Cancer and Their Prognostic Significance.

Background/Objectives: Histopathological indicators, including desmoplastic reaction (DR) and tumour budding (TB), are significant prognostic indicators for metastatic liver lesions in patients with colorectal cancer (CRC). However, the relationship of DR and TB in primary CRC and metastatic lung lesions and their prognostic significance has not yet been examined. This study aimed to elucidate the association of DR and TB in primary CRC and metastatic lung lesions. Methods: Patients with pT3 or pT4 CRC with lung metastasis who underwent surgical resection of the primary CRC and synchronous or metachronous metastatic lung lesions were enrolled. DR was classified into immature (IM) and non-IM types, and TB was classified into TB1 (<4 buds), TB2 (5-9 buds) and TB3 (≥10 buds) in both the primary CRC and metastatic lung lesions. Results: Overall, 40 patients with CRC (males, 21; females, 19; median age, 70 years; right-side colon, 6; left-side colon, 9; rectum, 25; pT3, 31; pT4, 9) were evaluated. Six and thirty-four patients were classified as having IM and non-IM DR in the metastatic lung lesions, respectively. Thirty-one, seven, and two patients were classified as having TB1, TB2, and TB3, respectively. There was no significant correlation between primary and lung metastatic lesions for DR (κ = 0.08, p = 0.086), whereas TB demonstrated a moderate correlation (κ = 0.47, p = 0.015). The presence of IM DR and TB2/3 in metastatic lung lesions significantly correlated with poor overall survival (p = 0.0020 and 0.044, respectively). Conclusions: histological indicators of metastatic lung lesions in CRC may provide important prognostic information for better patient care.