In recent years, the potential of a ketogenic diet as an adjunct to standard cancer care has raised interest among researchers. A ketogenic diet is rich in proteins and fats with comparatively few carbohydrates, normally in a ratio of 3 parts fats and proteins to less than 1 part carbohydrates. The diet, like fasting, prompts the body to convert triglycerides from fat stores into ketone bodies which can be used as an energy supply by the majority of cells, including muscle cells and neurons.
Previous pilot and feasibility trials have established the potential of a ketogenic diet as supportive treatment against cancer. Depriving cancer cells of glucose may reinstate apoptosis, ie. programmed cell death, in cancer cells. Therefore, the authors suggest “the use of a ketogenic diet as a supportive strategy for patients with tumors is a rational and empirically supported approach. “
Although there are some findings to the contrary, it has been found that a human enzyme known as TKTL1 may act as a genetic switch, enabling cancer cells to meet their increased demand on glucose supply required for proliferation. One of the aims of the present study was to investigate the effects of the novel marker TKTL1.
A total of 78 patients that had been diagnosed with any type of cancer were eligible for the study. Of the 78 patients included in the study, 18 presented with breast cancer, 16 with prostate cancer, 9 with colon cancer, 2 with melanoma, 5 with lung cancer, 5 with otolaryngological cancer and 23 with other types of cancer.
The patients were monitored regarding their levels of TKTL1, a novel tumour marker and the patients’ degree of adherence to a ketogenic diet. Tumour progression was documented according to oncologists’ reports.
Every 3 months, the patients were questioned regarding their eating habits in a clinical interview, and classified accordingly into 3 different groups, no ketogenic diet, partially ketogenic diet or strict ketogenic diet.
The variation in TKTL1 scores was calculated from the end of the observation period to baseline. A negative score indicated an improvement in tumour status over time, while a positive score corresponded to a deterioration of the disease.
Of the 78 patients, 13 (17%) had adopted a ketogenic diet, 6 of them partially (8%) and 7 in full (9%). None of the patients in endstage cancer adopted the diet fully, and 1 patient adhered partially to it.
The results include the following outcomes, as described by the authors of the study:
- In 4 palliative patients that adopted a strict ketogenic diet, 1 patient with metastatic breast cancer, who had embraced a strict ketogenic diet since 2009, experienced a full remission of all metastases in the lung and bones. This was verified by fludeoxyglucose‑PET analysis, which demonstrated no active metastases and 1 inactive metastasis in the thoracic region of the spine.
- In another palliative patient, who was diagnosed with cancer of the ovary in 1996 and had previously experienced cancer of the left and right breast in 1987 and 1998, respectively, followed by a recurrence of the carcinoma on the left side in 2006 and another recurrence in 2009, no further recurrences were detected during the observation period.
- A third patient with astrocytoma experienced a progression of the disease despite the ketogenic diet, although the high-dose corticosteroid therapy that the patient had received may have impacted their glucose metabolism.
- Those patients who had started on a strict ketogenic diet, but then stopped it, experienced initially a remission of the disease or the metastases, which rebounded once they had stopped the diet, frequently with lethal consequences.
The authors suggest a correlation was observed between an improvement of the disease and having adopted the ketogenic diet in full and that a reduction in TKTL1 score from baseline to the final measurement was associated with ketogenic diet and improvement in cancer status.
The authors state that the present study is believed to be the first to describe the effects of a ketogenic diet in patients with cancer in primary care.
They conclude that “i) TKTL1 is associated with a more active disease and a worse prognosis; ii) a ketogenic diet reduces the levels of TKTL1; and iii) increased levels of TKTL1 predict the development of endstage disease.”
The study proposes “that patients with a diagnosis of cancer (except those with endstage disease) can adopt a ketogenic diet and benefit from it, since those patients who embraced a ketogenic diet in the present study were observed to experience a halt in the progression of the disease or complete remission.”
The authors cautions that this was not a randomized study, but a study in general practice. There was no control condition or control group matched for important predictors. Therefore, the study is to be taken as guidance only and to prompt the design of rigorous randomized studies to validate the study observations.
In that light, the authors state “while the present study was not intended to validate this hypothesis, the results obtained suggest that there is a positive link between the expression of TKTL1 and cancer progression, and a negative link between ketogenic diet and TKTL1 expression. This also explains why a ketogenic diet may be useful in patients with cancer, since cancer cells rarely use or are unable to use ketone bodies. Thus a ketogenic diet would withdraw the nutrients and energy requirements of a growing tumour, but not of the physiological functioning of the body. Therefore, reduced expression levels of TKTL1, which are a negative predictor of cancer progression, may reflect the effect of a ketogenic diet.”
In conclusion, the authors put forward that the present study “has demonstrated that a ketogenic diet is feasible and likely beneficial for patients with cancer in primary care, who have been treated for their primary cancer, since it altered the expression of TKTL1, a novel and potentially useful marker to monitor the metabolic state of the body regarding aerobic glycolysis, and to evaluate the potential progression of non-endstage tumour disease.“
Jansen N, Walach H, The development of tumours under a ketogenic diet in association with the novel tumour marker TKTL1: A case series in general practice (2016) Oncol Lett. Jan;11(1):584-592.