Study Reveals Molecular, Clinical Features in Colorectal Cancer Cases Involving Multiple Primary Tumors

For a paper appearing in JAMA Network Open, researchers at Sun Yat-sen University and other centers in China present findings from a molecular and clinical analysis of a relatively rare form of colorectal cancer known as synchronous multiple primary colorectal cancer (sMPCC). With targeted next-generation sequencing, immunohistochemistry, and other approaches, the team profiled mismatch repair (MMR) status, microsatellite instability (MSI), and tumor mutational burden in 239 cases of sMPCC, comparing features to those found in single primary colorectal cancer cases enrolled over nearly a decade, from late 2012 to the spring of 2021. Along with higher-than-usual MMR deficiency and MSI in the sMPCC cases, the authors found frequent EGFR and PIK3CA alterations in the CRCs involving multiple primary tumors, while flagging three distinct sMPCC subgroups based on MMR and MSI status. "We propose that the MMR/MSI status of each lesion in patients with sMPCC should be verified before treatment," they suggest, adding that the current findings "indicate that patients with sMPCC with different MMR/MSI statuses may be treated with personalized therapies for better disease management."