Ketogenic Diet and Oncology Studies
The impact of the ketogenic diet on the growth of murine pancreatic tumors was evaluated by Yang and colleagues. The ketogenic diet decreased glucose concentration that enters the TCA cycle and increased fatty acid oxidation that produces β-hydroxybutyrate. This event promotes the generation of ATP, although with only modest elevations of NADH with less impact on tumor growth. The combination of ketogenic diet and standard chemotherapy substantially raised tumor NADH and suppressed the growth of murine tumor cells, they noted.14 Furukawa and colleagues compared 10 patients with metastatic colon cancer receiving chemotherapy plus the modified medium-chain triglyceride ketogenic diet for 1 year with 14 patients receiving chemotherapy only. The ketogenic diet group exhibited a response rate of 60% with 5 patients achieving a complete response and a disease control rate of 70%, while the chemotherapy-alone group showed a response rate of only 21% with no complete response and a disease control rate of 64%.15
The ketogenic diet also reportedly stimulates cytokine and CD4+ and CD8+ T-cell production that stimulates T-cell killing activity. The ketogenic diet may overcome several immune escape mechanisms by downregulating the expression of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1) on tumor-infiltrating lymphocytes.16 Our patient tolerated the combination of the ketogenic diet with ipilimumab (CTLA-4 inhibitor) and nivolumab (PD-1 inhibitor) without significant toxicities and stabilization of his disease.
Future Directions
We originally presented the abstract and poster of this case report at the Association of VA Hematology/Oncology annual meeting in San Diego, California, in September 2022.17 Based on our previous experience, we are now using a modified Atkins diet, which is a less strict diet consisting of 60% fat, 30% protein, and 10% carbohydrates combined with chemotherapy and/or immunotherapy. The composition of fat to carbohydrate plus protein in the traditional ketogenic diet is usually 4:1 or 3:1, while in modified Atkins diet the ratio is 1:1 or 2:1. The benefit of the modified Atkins diet is that patients can consume more protein than a strict ketogenic diet and they can be more liberal in carbohydrate allowances. We are about to open a study protocol of combining a modified Atkin diet and chemotherapy and/or immunotherapy as a first-line treatment for veterans with all types of advanced or metastatic solid tumors at VACCHCS. The study protocol was approved by the VA Office of Research and Development and has been submitted to the VACCHCS Institutional Review Board for review. Once approved, we will start patient recruitment.
CONCLUSIONS
Cancer cells have defects in their mitochondria that prevent them from generating energy for metabolism in the absence of glucose. They also depend on the PI3K signaling pathway to survive. The ketogenic diet has the advantage of affecting cancer cell growth by exploiting these mitochondrial defects and blocking hyperglycemia. There is growing evidence that the ketogenic diet is feasible, tolerable, and reportedly inhibits cancer growth. Our case report and previous publications suggest that the ketogenic diet can be added to chemotherapy and/or immunotherapy as an adjunct to standard-of-care cancer treatment while maintaining good QOL. We are planning to open a clinical trial using the modified Atkins diet in conjunction with active cancer treatments as first-line therapy for metastatic solid tumors at the VACCHCS. We are also working closely with researchers from several veteran hospitals to do a diet collaborative study. We believe the ketogenic diet is an important part of cancer treatment and has a promising future. More research should be dedicated to this very interesting field.
Acknowledgments
We previously presented this case report in an abstract and poster at the September 2022 AVAHO meeting in San Diego, California.