SMAD4 gene mutation predicts poor prognosis in patients undergoing resection for colorectal liver metastases

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• The mothers against decapentaplegic homolog 4 (SMAD4) protein is crucial in the transforming growth factor (TGF)-β signaling pathway.
• SMAD4 gene mutations are implicated in colorectal cancer (CRC) progression, but their impact on survival after resection of colorectal liver metastases (CLM) is not well understood.

Purpose of the Study:

• To investigate the association between SMAD4 mutation status and overall survival (OS) in patients undergoing resection of CLM.
• To validate the prognostic value of SMAD4 mutations in a separate cohort of patients with stage IV CRC treated with systemic therapy.

Main Methods:

• Retrospective analysis of 278 patients with known SMAD4 mutation status who underwent CLM resection (2005-2015).
• Comparison of survival outcomes between SMAD4-mutant and SMAD4 wild-type patients.
• Validation in a cohort of 237 patients with synchronous stage IV CRC receiving systemic therapy alone.

Main Results:

• SMAD4 mutations were present in 13% of CLM resection patients and were associated with significantly worse OS (3-year OS: 62% vs. 82%; P < 0.0001).
• SMAD4 mutation was an independent predictor of worse OS, alongside poor differentiation, multiple tumors, tumor diameter >3 cm, R1 margin, and RAS mutation.
• In the validation cohort, SMAD4 mutations were also linked to worse 3-year OS (22% vs. 38%; P = 0.012) and were an independent prognostic factor (HR, 1.647; P = 0.032).

Conclusions:

• SMAD4 mutation is an independent molecular marker associated with unfavorable outcomes in patients with CLM undergoing surgical resection.
• The findings suggest that SMAD4 mutation status can inform prognosis and potentially guide treatment strategies for patients with advanced colorectal cancer.