Photodynamic Therapy for Colon Cancer

PICHON RIVIERE, A.; AUGUSTOVSKI, F.; GARCIA MARTI, S.; GLUJOVSKY, D.; ALCARAZ, A.; LOPEZ, A.; BARDACH, A.; CIAPPONI, A; GONZALEZ, L

Documento de Evaluación de Tecnologías Sanitarias

IECS

Año: 2012 p. 1 - 30

1668-2793

Colorectal cancer (CRC) incidence has increased in the last decades and it is one of the most common neoplasms in industrialized countries. Its annual incidence is 50/100,000 people, affecting 90% of people over 50. In our setting, its incidence ranks second in women after breast cancer and in men it follows lung and prostate cancer. Its median age of diagnosis is 70 years old. To define CRC as advanced (ACRC), both at the time of initial diagnosis and at recurrence, the tumor should have metastasized or should have invaded, locally, the intestinal wall. Approximately 30% of the people with CRC diagnosis have ACRC, and 50% of those who are not at advanced stages at onset, progress during the course of the disease, requiring systemic chemotherapy. In the last decade, it was seen that, based on the result of several trials, there is an increase in the overall median survival from 12 to 21 months when the available chemotherapy agents are administered. In addition to systemic chemotherapy treatments, in the last years endoscopic treatments have been developed to palliate colon and rectal obstructions. Nd:YAG (yttrium argon) laser therapy is the most commonly used technique for endoscopic ablation, many times together with stent placement. Other treatments include cryotherapy, argon plasma coagulation and photodynamic therapy. This technique has been postulated to palliate obstruction in colorectal cancer as well as for metastasis management in patients in whom surgery is not possible.TechnologyPDT involves the initial marking of pathological tissue using an intravenous photosensitizer agent and later a tissue destruction process, by exposing it to a light source with a specific wavelength. This triggers the production of reactive oxygen molecules and a cascade of events leading to neoplastic cell destruction.PurposeTo assess the available evidence on the efficacy, safety and coverage policy related aspects on the use of photodynamic therapy in patients with colorectal cancer.MethodsA bibliographic search was carried out on the main databases: DARE, NHS EED, on Internet general search engines, in health technology evaluation agencies and health sponsors. Priority was given to the inclusion of systematic reviews; controlled, randomized clinical trials (RCTs); health technology assessments and economic evaluations; clinical practice guidelines and coverage policies of other health systems.ResultsNo RCT, systematic reviews, economic evaluations, clinical practice guidelines or health technology evaluations where found on the subject. Very little evidence was found about the clinical experience on PDT use for colon or rectal cancer, or liver metastasis treatment, secondary in these types of tumors; most of them were small case series.One of the studies published in 1995, performed 5-aminolevulinic acid (5-ALA) sensitization to 8 patients with colon cancer. The concentrations of the sensitizer achieved were lower than those achieved in patients with esophageal or duodenal cancer, assessed in the same study. Tumor tissue necrosis was observed, although the study did no state if the therapeutic objective was achieved.Regarding its use in the case of metastasis, one study published in 2005 evaluated 24 subjects with liver metastasis using mTHPBC sensitizer. At one month follow-up, tumor necrosis was achieved in all the treated lesions. The treatment was associated with mild pain and subclinical liver toxicity. One patient developed pancreatic injury and another, non-serious cutaneous injury.An ongoing protocol was also identified, at the time of patient recruitment, registered at cancer.gov/clinicaltrials. It will perform PDT with 5-ALA to colon cancer subjects.A U.S. health sponsor considers photodynamic therapy as experimental and under research in colon cancer because its efficacy for this indication has not been proven yet.ConclusionsThe evidence found is of very poor quality. There is not enough evidence to determine de effectiveness and safety profile or PDT for colon and rectal cancer, or to recommend its use as endoscopic treatment to palliate colon or rectal obstruction, replacing standard treatments such as stent placement or laser therapy.Regarding liver metastasis in these malignancies, there were isolated experiences reported as case series with a low number of patients which show promising results. However, the fact that there are not controlled studies comparing PDT to the standard management of these patients causes PDT use, either for curative or palliative intent in colon and rectal cancer, still to be considered experimental.