BY Samuel E. Mathis, MD, MBA, CPE, FAAF, Assistant Professor, Fellowship Director, UTMB Integrative & Behavioral Medicine Fellowship, WD & Laura Nell Nicholson Family Professorship in Integrative Medicine, Department of Family Medicine, University of Texas Medical Branch
Recently, I have had several conversations about the benefits of exercise. We know that exercise has significant health benefits in reducing the risk of chronic diseases such as hypertension, diabetes, and cardiovascular disease. It also improves sleep quality, decreases symptoms of anxiety and depression, and can improve cognitive function. One of these conversations looked at the effect exercise has on cancer risk (both prevalence and recurrence). This sent me on a deep dive into the effect of exercise on cancer risk that I would like to share with you.
Before we discuss the research, we must first understand the idea of Metabolic Equivalents (MET). METs refer to the amount of oxygen consumption necessary for sustaining basal metabolic functions at rest. It is equivalent to 3.5ml O2 per kg of bodyweight x min. All activities increase the amount of METs used above baseline. For example, jogging/running utilizes 8-15 METs per minute, cycling can use 5-10 METS, and housework uses 2-5 METs. The World Health Organization (WHO) currently recommends a minimum of 600 MET-minute/week for health benefits (1). More strenuous activities result in higher METs for that activity.
Diao et al.’s 2023 systematic review looked at 98 different studies and found that the amount of exercise one participates in has an inverse relationship to the risk of cancer (2). This study reviewed publications examining the effect of exercise on breast, lung, colon, gastric, and liver cancer. It did not include studies on blood, endocrine, brain, genitourinary, and bone cancers. Individuals who had more than 8,000 MET-minutes/week had the following decreased risk of cancer compared to those who did not exercise: breast – 10.3%; lung – 5.9%; colon – 7.1%; gastric – 5.1%; liver – 17.1%. Interestingly, lung cancer had the greatest risk reduction (14.7%) at more than 13,200 MET-minutes/week.
In individuals who are diagnosed with cancer, exercise can be vital to helping them maintain their quality of life. Physical activity during cancer treatment has been shown to reduce side effects of treatment such as pain, nausea, and fatigue. It helps with sleep and mood. A systematic review of both preclinical and clinical trials found that exercise enhanced the efficacy of chemotherapy drugs in preclinical trials and helps improve completion rates for patients being treated with chemotherapy (3). It is important to note that this study was relatively small (only 7 clinical trial), and focused on very limited cancers (breast, colon, and lymphomas). However, the preliminary data was encouraging that there is a benefit to encouraging exercise in our cancer patients.
So how can we address this topic with our patients? One of the easiest ways is to promote the American Heart Association’s exercise recommendations. They recommend that all adults should have at least 150 minutes of moderate intensity exercise per week and 2 days a week of high intensity weight training activity per week. This roughly equates to 30 minutes of a brisk walk, jog, or swim 5 days a week. To get patients started, I typically recommend patient engage in 20 minutes a day of a brisk walk and then to expand it as they get more comfortable. While more exercise is definitely better, some is always better than none. For those individuals who can’t afford to go to a gym for weight training, I recommend using what’s in the house. A gallon of water or milk weighs about 8.5 pounds which is plenty for most people. You can do simple curls, shoulder raises, and triceps extensions for upper body workouts. Additionally, holding them while doing lunges or squats can provide an extra challenge to the activity. The point is to meet patients where they are at and help them identify ways to improve their own health one step at a time.
References:
- Jetté M, Sidney K, Blümchen G. Metabolic equivalents (METS) in exercise testing, exercise prescription, and evaluation of functional capacity. Clin Cardiol. 1990 Aug;13(8):555-65. doi: 10.1002/clc.4960130809. PMID: 2204507.
- Diao X, Ling Y, Zeng Y, Wu Y, Guo C, Jin Y, Chen X, Feng S, Guo J, Ding C, Diao F, Du Z, Li S, Qiu H. Physical activity and cancer risk: a dose-response analysis for the Global Burden of Disease Study 2019. Cancer Commun (Lond). 2023 Nov;43(11):1229-1243. doi: 10.1002/cac2.12488. Epub 2023 Sep 24. PMID: 37743572; PMCID: PMC10631483.
- Yang L, Morielli AR, Heer E, Kirkham AA, Cheung WY, Usmani N, Friedenreich CM, Courneya KS. Effects of Exercise on Cancer Treatment Efficacy: A Systematic Review of Preclinical and Clinical Studies. Cancer Res. 2021 Oct 1;81(19):4889-4895. doi: 10.1158/0008-5472.CAN-21-1258. Epub 2021 Jul 2. PMID: 34215623; PMCID: PMC9397632.