Biology or Technical Error? Association Between Microsatellite Instability and Positive Margins in Stage I-III Colon...

Area of Science:

• Oncology
• Surgical Pathology
• Cancer Genomics

Background:

• European studies linked microsatellite instability (MSI) to increased positive surgical margins in stage III colorectal cancer.
• This association suggested tumor biology, not surgical technique, might be responsible for positive margins.
• A US-based national registry was used to validate these European findings.

Purpose of the Study:

• To validate European observations on the association between MSI and positive surgical margins in a US cohort.
• To investigate the prognostic impact of MSI and positive surgical margins in stage I-III colon cancer.

Main Methods:

• Analysis of adult patients with pathologic stage I-III colon adenocarcinoma from the National Cancer Database (2010-2020).
• Statistical analysis to determine the association between MSI status, positive margins, and patient prognosis.

Main Results:

• MSI was independently associated with positive margins in stage III colon cancer (OR 1.10).
• Positive margins correlated with worse prognosis in stage II (HR 1.26) and stage III (HR 1.40) colon cancer.
• MSI conferred a lower risk of death in stage III cancer (HR 0.87) but not in stage I or II.

Conclusions:

• This US study confirms MSI is linked to higher odds of positive margins in stage III colon cancer.
• Findings suggest a need for quality improvement initiatives and evaluation of neoadjuvant treatments.
• The study highlights the importance of considering tumor biology in managing colon cancer.