Significant response to photodynamic therapy combined with systemic therapy in locally advanced rectal cancer: a case report

The rising incidence of colorectal cancer (CRC) necessitates the exploration of new treatment strategies. This study investigates the potential of photodynamic therapy (PDT) combined with systemic immunotherapy and targeted therapy as a neoadjuvant treatment for locally advanced CRC. A patient with locally advanced CRC underwent four PDT sessions under colonoscopy, followed by systemic therapy with Capecitabine, Bevacizumab, and Sintilimab. Hematologic markers and imaging assessments were conducted every two cycles. After six treatment cycles, tumor markers normalized. Abdominal MRI showed near-complete resolution of the tumor, with significant improvement in intestinal wall thickening and reduction of lymph nodes in the perirectal fat gap. No extramural venous invasion was observed. PDT combined with systemic therapy may offer a promising neoadjuvant approach for locally advanced rectal cancer, with the potential for tumor regression and conversion to surgical resection.