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

BackgroundPeritoneal 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.MethodsWe systematically reviewed the evidence of using PDT to treat peritoneal carcinomatosis in both animals and humans (Medline/EMBASE searched in June 2017).ResultsThree 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).ConclusionPDT 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.