Abstract / Summary
The management of patients with multiple synchronous primary tumors remains challenging, particularly in individuals who are not candidates for surgery. While immune checkpoint inhibitors (ICIs) have demonstrated remarkable efficacy in deficient mismatch repair (dMMR)/microsatellite instability-high (MSI-H) tumors, evidence supporting their use as a non-operative strategy in patients with multiple malignancies is limited, as this population is excluded from clinical trials. We report three cases of patients with synchronous primary tumors, including gastrointestinal malignancies with dMMR status, treated with up-front ICIs. Treatment strategies were individualized based on the patient’s clinical condition, tumor burden, and molecular profile. All patients achieved meaningful and durable responses with long-term survival exceeding two to four years, supporting the feasibility of a non-operative strategy and organ preservation in carefully selected patients, including the frail subgroup population. Immunotherapy-based approaches were well tolerated, with a manageable safety profile. Notably, none of our patients underwent surgical resection. However, these observations are hypothesis-generating and cannot establish the efficacy or equivalence of immunotherapy to standard surgical management. Our findings extend current evidence to a largely underrepresented population and support a personalized, multidisciplinary, response-adapted approach. Prospective studies are warranted to better define patient selection, optimal treatment duration, and long-term outcomes of non-operative strategies in this setting.