McGill University
Presentation Abstract
Nutritional Interventions in Oncology
Classic laboratory studies performed more than 50 years ago provided fascinating evidence that dietary modifications (mostly caloric restriction) can substantially reduce cancer risk and slow cancer growth. I will review this work and discuss proposed underlying mechanisms and argue that clinical relevance of these studies has yet to be established. Furthermore, the notion that one can ‘starve’ cancer cells by reducing food intake is now recognized as simplistic. However, more recent studies provide evidence that more specific dietary manipulations do deserve study. These include, as examples, intermittent fasting and serine/glycine deprivation. However, none of these dietary interventions have been established to have clinical benefit.
Importantly, there is a paucity of evidence to support certain dietary advice emphasizing the need to avoid cachexia, which is often given to cancer patients undergoing treatment. Many patients, even if they are not cachexic, use commercial high caloric macronutrient supplements known to increase glucose and insulin levels in a manner that may be counter-productive. This may be exacerbated if patients are on glucocorticoids. In contrast, some patients or health care providers who are aware of studies demonstrating adverse effects of obesity on risk or prognosis of certain cancers try to lose weight by dieting or exercising. While this appears sensible, there is a lack of clinical studies to prove the approach has efficacy, and it is unknown if (for example) an obese post-menopausal breast cancer patient or prostate cancer patient can improve their outcome by dieting.
Recent work has shown potentially important interactions between diet and efficacy of certain targeted cancer therapies, for example that diets that reduce insulin levels are associated with improved efficacy of drugs that target PI3K inhibitors.
There are major gaps in knowledge regarding the best dietary advice to give to individuals seeking to lower cancer risk or improve cancer prognosis. Clinical trials of dietary interventions to reduce cancer risk are extremely difficult to execute, as they require prolonged observation of large numbers of subjects while monitoring for compliance. Clinical trials of dietary interventions to improve cancer outcomes or increase efficacy or decrease toxicity of co-administered therapies are also challenging to execute, but the periods of observation are usually months rather than years.
About Dr. Pollak
Dr. Michael Pollak is a tenured Professor in the Department of Oncology at McGill University in Montreal and holds the Alexander-Goldfarb Research Chair. His medical education was at McGill University and post-graduate specialist training in Oncology was at the University of Toronto. He practices medical oncology at the Jewish General Hospital and also leads laboratory and population-based research programs. He heads the Division of Cancer Prevention at the Department of Oncology at McGill University and the Stroll Cancer Prevention Centre at the Jewish General Hospital (JGH).
Dr. Pollak has published more than 500 scientific papers with a total of over 42,500 citations, and an H-index of 120, placing him in the top 10% of researchers in terms of citations and research impact.
He collaborates widely with researchers around the world and has received more than $25 million in peer-reviewed funding. In 2012, he was awarded the Aisenstadt Award for Academic Achievement by McGill/JGH faculty and the Harold Warwick Prize by the Canadian Cancer Society Research Institute. In 2018, he was appointed Co-Editor-in-Chief, Cancer Prevention Research, by the American Association for Cancer Research (AACR) and elected to the Royal Society of Canada (RSC) the following year. He also is Co-Editor-in-Chief of Cancer Metabolism, a specialty journal published by Springer-Nature. His research focuses on the intersection of oncology, endocrinology, and metabolism and he employs a multidisciplinary approach, using both laboratory and population methods.
Dr. Pollak did not disclose any conflicts of interest for this workshop.