- Interview "Foods rich in glucose are allies of cancer"
Diet has a close relationship with cancer. The diet we eat influences the incidence, growth and development of cancer. Thus, it is well known that one-third of the most common cancers can be prevented, at least in part, by changes in diet. Its usefulness as a complementary tool against cancer is also explored, although the results have not yet reached the clinic.
The Growth Factors, Nutrients and Cancer group of the Spanish National Cancer Research Centre (CNIO), led by Nabil Djouder, defends the importance of taking diet into account in treatments. In that sense, the team has just published in Trends in Molecular Medicine a review on the use of diet in cancer treatment, with Carlos Martínez-Garay as first author.
"Diets can directly target cancer metabolism, by depriving the tumor of the nutrients it needs, or they can affect other key elements for cancer survival and development, such as growth signaling, oxidative stress or patient immunity," says Djouder.
For the authors, one of the reasons why these nutritional therapies are not yet being applied in cancer patients is that the clinical studies conducted so far have limitations. For example, many of these trials group patients with very heterogeneous tumor profiles. Strict standards for the implementation of diets as a treatment are also lacking.
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The current work reviews the possible therapeutic nutritional interventions against cancer, and the steps that remain before they are considered standard treatment. With this review the authors aim to contribute to the design of new clinical trials and translational studies in this area.
The work focuses on calorie restriction, the ketogenic diet and intermittent fasting, analyzing how they can influence the appearance and development of tumors. After reviewing recent or ongoing preclinical studies and clinical trials on these diets, it offers a new perspective on the physiological underpinnings behind them.
The authors review in depth what is known about nutrient metabolism and its relationship to the appearance and progression of tumors. Data suggest that the growth of some cancers may depend heavily on specific amino acids, and that avoiding foods rich in these amino acids could limit tumor growth.
Obesity, Microbiome and Cancer
In addition, many of the pathways associated with tumor proliferation are linked to hormones sensitive to certain nutrients. This could explain the relationship between obesity and cancer, due precisely to an increase in the signaling of estrogens (hormones) produced by adipose tissue (fat).
Researchers have also reviewedpublications that link gut flora to cancer. The gut flora or microbiome groups together the population of microbes present in the intestinal tract and is one of the main responsible for the interaction between what a person eats and their health.
"Many of the oncogenic effects attributed to the gut microbiome," explains Carlos Martínez-Garay, "are related to inflammation of the digestive tract and, in fact, the presence of certain populations of bacteria is linked to chronic inflammation that is associated with gastrointestinal cancers such as gallbladder, bile duct and stomach."
One of the main factors responsible for tumor growth, and whether the therapy chosen to fight each cancer is successful or not, is the interaction between tumor cells and the patient's immunity, and in this case there is also a relationship with diet. Most of our immune cells are present in the gut as a defense barrier against the ingestion of toxic compounds or pathogens.
"Certain components of the diet can provoke important responses in the immune system," says Martínez-Garay, "and this can cause a dysfunction in our defenses that makes us more vulnerable to the formation of tumors."
Precision nutrition for every patient
The authors point to the need to develop precision nutrition, a novel approach that proposes the use of targeted dietary regimens to treat specific tumors based on tumor and patient metabolism. The current ability to analyze tumors in depth and classify them according to their molecular profile has allowed a great advance in the effectiveness of therapies to combat them.
Nabil Djouder explains: "This can also be applied to nutrition if clinical data, microbiome examinations, molecular diagnostics, nutrigenomics and metabolomics are combined to develop specific dietary regimens aimed at treating cancer patients individually. The preclinical studies and clinical trials we have reviewed show the potent effects of dietary interventions and this makes us think that a new era in cancer therapy is coming."
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