The international surgical journal with global reach

This is the Scientific Surgery Archive, which contains all randomized clinical trials in surgery that have been identified by searching the top 50 English language medical journal issues since January 1998. Compiled by Jonothan J. Earnshaw, former Editor-in-Chief, BJS

Histopathological and molecular classification of colorectal cancer and corresponding peritoneal metastases. BJS 2018; 105: e204-e211.

Published: 17th January 2018

Authors: I. Ubink, W. J. van Eden, P. Snaebjornsson, N. F. M. Kok, J. van Kuik, W. M. U. van Grevenstein et al.

Background

Patients with colorectal peritoneal carcinomatosis have a very poor prognosis. The recently developed consensus molecular subtype (CMS) classification of primary colorectal cancer categorizes tumours into four robust subtypes, which could guide subtype‐targeted therapy. CMS4, also known as the mesenchymal subtype, has the greatest propensity to form distant metastases. CMS4 status and histopathological features of colorectal peritoneal carcinomatosis were investigated in this study.

Method

Fresh‐frozen tissue samples from primary colorectal cancer and paired peritoneal metastases from patients who underwent cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy were collected. Histopathological features were analysed, and a reverse transcriptase–quantitative PCR test was used to assess CMS4 status of all collected lesions.

Results

Colorectal peritoneal carcinomatosis was associated with adverse histopathological characteristics, including a high percentage of stroma in both primary tumours and metastases, and poor differentiation grade and high‐grade tumour budding in primary tumours. Furthermore, CMS4 was significantly enriched in primary tumours with peritoneal metastases, compared with unselected stage I–IV tumours (60 per cent (12 of 20) versus 23 per cent; P = 0.002). The majority of peritoneal metastases (75 per cent, 21 of 28) were also classified as CMS4. Considerable intrapatient subtype heterogeneity was observed. Notably, 15 of 16 patients with paired tumours had at least one CMS4‐positive tumour location.

Conclusion

Significant enrichment for CMS4 was observed in colorectal peritoneal carcinomatosis.

Surgical relevance

Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (CRS‐HIPEC) improves survival of selected patients with colorectal peritoneal carcinomatosis, but recurrence is common. Histopathological and molecular analysis of colorectal peritoneal carcinomatosis could provide clues for development of novel therapies.

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