Breast Cancer and Intermittent Fasting

Breast cancer (BC) is the most common malignancy in women, followed by non-melanoma skin neoplasms. BC is responsible for approximately 25% of new malignancy cases and 14% of neoplasm-induced deaths in women. Obesity has been identified as a risk factor for BC development and recurrence in previous epidemiological studies, and strategies for optimal body weight are considered essential in the primary and secondary prevention of this clinical entity [1].Caloric restriction (CR) without malnutrition has been identified as one of the most effective cancer prevention interventions in mammals. Continuous energy restriction (CER), defined as a daily 30% reduction in basic metabolic rate while maintaining required amounts of vitamins, minerals, and other nutrients, combined with a less sedentary lifestyle, is a common weight loss strategy. Despite this, available research indicates a moderate level of adherence within 1-4 months of dietary intervention. Alternative dietary regimens have been proposed in this regard, including intermittent energy restriction (IER) as an umbrella term that includes two different subtypes of fasting: intermittent fasting (IF) and time-restricted feeding (TRF). Intermittent fasting (IF) consists of short periods of severe energy restriction followed by periods of normal caloric intake [2].

How to follow intermittent fasting in Breast Cancer

IF dietary patterns include long periods of little to no caloric consumption (e.g., 16-48 h) alternated with periods of ad libitum intake (at one's pleasure, abbreviated to "ad lib"). Alternate-date fasting (ADF), alternate-day modified fasting (ADF), fasting 2 days per week (2DW), and periodic fasting (PF) lasting 2-21 days is all IF variations. The ADF IF subtype alternates between days when the energy limit is 75%, known as the "fast day," and days when food is eaten as needed. Time-restricted feeding (TRF) is an IF diet that focuses on eating within a specific time frame, usually between 6 and 12 hours [3,4,5].

Essence of modern studies for the effect of IF on breast cancer

While chronic caloric deficit cannot be implemented in cancer patients, short fasting periods may be a viable alternative as a candidate adjunctive tool for cancer prevention and treatment. The results of available studies, however, are contradictory, particularly for certain types of cancer, including BC. This is primarily due to a lack of high-quality evidence, despite available preclinical data indicating that IF may be beneficial in chemotherapy-related toxicity and tumor growth. Scientists investigated the impact of IF   on previously diagnosed cancer patients in terms of quality of life during chemotherapy, chemotherapy-related toxicity, radiological response, BC recurrence, endocrine-related outcomes, and IF-induced outcomes. Previous studies reported that short periods of very low caloric intake, such as short-term fasting (2- 4 days) or dietary manipulation of specific macronutrients, can be effective in delaying primary tumor growth. Excess consumption of animal-derived protein, on the other hand, has been linked to an increased risk of cancer and all-cause mortality. Intermittent fasting (IF) and time-restricted feeding (TRF) are broadly defined by cyclical periods of low caloric intake or complete fasting interspersed with periods of ad libitum (AL) feeding. IF and TRF cause a significant reduction in tumor growth and have gained popularity as an adjuvant to chemotherapy as well as a cancer prevention tool [1].

References:

1.      1. Anemoulis, M.; Vlastos, A.; Kachtsidis, V.; Karras, S.N. Intermittent Fasting in Breast Cancer: A Systematic Review and Critical Update of Available Studies. Nutrients 2023, 15, 532.slational applications.

2.      2. Canadian Cancer Statistics Advisory Committee. Canadian Cancer Society. 2021. Available online: https://cancer.ca/en/cancer‐ information/cancer‐types/breast/statistics (accessed on 14th February 2022).

3.     3. Rynders, C.A.; Thomas, E.A.; Zaman, A.; Pan, Z.; Catenacci, V.A.; Melanson, E.L. Effectiveness of Intermittent Fasting and Time‐ Restricted Feeding Compared to Continuous Energy Restriction for Weight Loss. Nutrients 2019, 11, 2442. https://doi.org/10.3390/nu11102442

4.      4. Sundaram, S.; Yan, L. Time‐restricted feeding mitigates high‐fat dietenhanced mammary tumorigenesis in MMTV‐PyMT mice. Nutr. Res. 2018, 59, 72–79.

5.     5.  Mas, S.; Le Bonniec, A.; Cousson‐Gélie, F. Why do women fast during breast cancer chemotherapy? A qualitative study of the patient experience. Br. J. Health Psychol. 2019, 24, 381–395. https://doi.org/10.1111/bjhp.12358.