Treatment of peritoneal carcinomatosis with photodynamic therapy: Systematic review of current evidence

Background: Peritoneal carcinomatosis results when tumour cells implant and grow within the peritoneal cavity. Treatment and prognosis vary based on the primary cancer. Although therapy with intention-to-cure is offered to selective patients using cytoreductive surgery with chemotherapy, the prognosis remains poor for most of the patients. Photodynamic therapy (PDT) is a cancer-therapeutic modality where a photosensitiser is administered to patients and exerts a cytotoxic effect on cancer cells when excited by light of a specific wavelength. It has potential application in the treatment of peritoneal carcinomatosis. Methods: We systematically reviewed the evidence of using PDT to treat peritoneal carcinomatosis in both animals and humans (Medline/EMBASE searched in June 2017). Results: Three human and 25 animal studies were included. Phase I and II human trials using first-generation photosensitisers showed that applying PDT after surgical debulking in patients with peritoneal carcinomatosis is feasible with some clinical benefits. The low tumour-selectivity of the photosensitisers led to significant toxicities mainly capillary leak syndrome and bowel perforation. In animal studies, PDT improved survival by 15-300%, compared to control groups. PDT led to higher tumour necrosis values (categorical values 0-4 [4 = highest]: PDT 3.4 +/- 1.0 vs. control 0.4 +/- 0.6, p < 0.05) and reduced tumour size (residual tumour size is 10% of untreated controls, p < 0.001). Conclusion: PDT has potential in treating peritoneal carcinomatosis, but is limited by its narrow therapeutic window and possible serious side effects. Recent improvement in tumour-selectivity and light delivery systems is promising, but further development is needed before PDT can be routinely applied for peritoneal carcinomatosis.