Blue Cross and Blue Shield of Montana (BCBSMT) considers insulin potentiation therapy (IPT) experimental, investigational and unproven.
Insulin potentiation therapy (IPT) has been explored in a minority of physician practices since the 1930s. However, there is only one randomized controlled trial on the effects of insulin potentiation therapy in metastatic breast cancer. No studies have demonstrated that IPT is safe or effective in improving long-term health outcomes over standard or conventional pharmacologic treatment for any disease state. In addition, it appears this is not an area of active research.
The only randomized controlled clinical trial (RCT) on IPT was published in 2004 by Lasalvia-Prisco and colleagues, who reported on 30 patients (three groups of 10) randomized to receive two 21-day courses of insulin with methotrexate (IPT), methotrexate alone, or insulin alone. Patients had metastatic breast cancer that was resistant to fluorouracil, adriamycin, and cyclophosphamide as well as hormone therapy (if they had a positive estrogen receptor status). The primary outcome assessed at eight weeks after initiation of treatment was tumor response using the response evaluation criteria in solid tumors (RECIST) system. The authors reported finding the RECIST status in the IPT group was nine stable diseases and one progressive disease versus three stable diseases and seven progressive in the methotrexate-only group, and two stable diseases and eight progressive in the insulin-only group (distribution of results = p<0.01, Chi-squared test). In addition, the IPT group had significantly lower increases in tumor size than the methotrexate-only and the insulin-only treatment groups (p<0.001). Toxicities were low in both the IPT group (only one World Health Organization [WHO] grade 1 mucositis) and the methotrexate-only group (WHO grade 1-2) as the individual methotrexate dosage of 2.5 mg/m² used in the study was lower than optimal. The authors suggest that these findings support the theory that the antitumoral effects of methotrexate were potentiated by the use of insulin. While this study may suggest insulin enhances some biochemical event with the administration of chemotherapy in the short term, it does not report on any long-term effects or health outcomes. Therefore, further studies are needed to demonstrate any improvements in health outcomes with the use of insulin potentiation therapy.
A 2006 publication described preclinical safety and antitumor efficacy of insulin combined with irradiation. Using the intestinal crypt regeneration assay, a delay in regrowth was noted when insulin therapy was combined with radiation. The need for larger preclinical assays was noted by the authors as a next step, before studies of possible clinical utility are conducted. Additional basic science research is currently being conducted on the role of insulin growth factors in cancer.
A search of the ClinicalTrials.gov US Clinical Trials Registry revealed that no trials investigating the treatment of fibromyalgia, chronic fatigue syndrome, arthritis, or infections have been published or are currently recruiting subjects.
Practice Guidelines and Position Statements
In 2008, the American Cancer Society released the following statement: “Despite supporters' claims that insulin potentiation therapy has been well researched, no scientific studies that show safety and effectiveness have been published in available peer-reviewed journals. These claims cannot be verified. There are also concerns about using lower doses of chemotherapy drugs. When chemotherapy drugs are tested in clinical trials, their effects are carefully monitored to learn which dose will best balance the need to kill cancer cells with the goal of keeping side effects at a tolerable level. There is no evidence that chemotherapy at a fraction of the recommended and tested dose can produce the same effect as the full dose if used with insulin.”
Much of the information about IPT comes from short-term anecdotal reports. A single randomized controlled trial suggested that tumor progression can be affected by IPT at eight weeks. No survival or longer term data are available. Therefore, further studies are needed to demonstrate whether improvements in health outcomes occur with the use of insulin potentiation therapy; the coverage position remains unchanged.