Peritoneal carcinomatosis occurs frequently in patients with advanced stage gastrointestinal and gynecological
cancers. The wide-spread peritoneal
micrometastases indicate a poor outlook, as the
tumors are difficult to diagnose and challenging to completely eradicate with
cytoreductive surgery and chemotherapeutics. Photodynamic diagnosis (PDD) and
therapy (
PDT), modalities that use
photosensitizers for fluorescence detection or photochemical treatment of
cancer, are promising
theranostic approaches for
peritoneal carcinomatosis. This review discusses the leading clinical trials, identifies the major challenges, and presents potential solutions to advance the use of PDD and
PDT for the treatment of
peritoneal carcinomatosis. While PDD for fluorescence-guided surgery is practically feasible and has achieved clinical success, large randomized trials are required to better evaluate the survival benefits. Although
PDT is feasible and combines well with clinically used chemotherapeutics, poor
tumor specificity has been associated with severe morbidity. The major challenges for both modalities are to increase the
tumor specificity of the
photosensitizers, to efficiently treat peritoneal microtumors regardless of their phenotypes, and to improve the ability of the excitation light to reach the
cancer tissues. Substantial progress has been achieved in (1) the development of targeted
photosensitizers and nanocarriers to improve
tumor selectivity, (2) the design of biomodulation strategies to reduce treatment heterogeneity, and (3) the development of novel light application strategies. The use of X-ray-activated
PDT during whole abdomen
radiotherapy may also be considered to overcome the limited tissue penetration of light. Integrated approaches that take advantage of PDD,
cytoreductive surgery,
chemotherapies,
PDT, and potentially
radiotherapy, are likely to achieve the most effective improvement in the management of
peritoneal carcinomatosis.