How much brisk exercise is needed to cut digestive cancer risk?

A growing body of evidence shows that people who exercise more have lower risk of developing digestive system cancers such as esophageal, colon, pancreatic or liver cancer. But how much do you need? 

The American Cancer Society now recommends that adults get in 150–300 minutes moderate-intensity exercise such as brisk walking or 75–150 minutes of vigorous physical activity such as running. Is it enough?

For a study published today in JAMA Oncology, researchers examined data on more than 230,000 people who were followed over more than three decades to determine the association between consistently exercising more and patients’ risk of digestive system cancers, which account for about 30% of all cancers in the U.S. 

To help do that, researchers used the metabolic equivalent task (MET) metric which, the study notes, “designates metabolic rates for a specific activity divided by metabolic rates at rest.” 

Here are the key takeaways that oncologists and other physicians need to know, as reported in the JAMA Oncology study, “Consistent Adherence to Physical Activity Guidelines and Digestive System Cancer Risk and Mortality.”

Question: Is consistent adherence to the recommended physical activity level (7.5 MET-hours per week) over time associated with lower digestive system cancer (DSC) risk? 

Findings: In this cohort study of 231,067 men and women followed up for up to 32 years, traditional dose-response analyses suggested that approximately 50 MET-hours per week was associated with optimal DSC risk reduction. After incorporating long-term consistency, consistently reaching the guideline at moderate levels (median, 17 MET-hours per week) was associated with substantial reductions in DSC risk, whereas performing much higher levels (i.e., consistently approximately 39 MET-hours per week) was not associated with further benefit. 

Meaning: The findings of this study suggest that maintaining a moderate level of physical activity of approximately 17 MET-hours per week (that is, five hours of brisk walking or two hours of running each week) over three decades was sufficient to achieve optimal benefit in reducing DSC risk.

A JAMA Oncology editorial published with the study lends perspective on the findings.

“The optimal dose of consistent physical activity to reduce DCS risk and mortality at approximately 17 MET-hours per week more than doubles the recommended guidelines. This suggests that much higher levels of physical activity than currently recommended are needed to achieve the greatest protective benefits,” says the editorial.

“Achieving 17 MET-hours per week can be met in several ways,” notes the editorial. Examples include: “brisk walking (moderate-intensity) for 60 minutes on four days per week; jogging (vigorous-intensity) for 25 minutes on five days per week; or, a combination of jogging 20 minutes three days a week with 45 minutes brisk walking on three other days.”

AMA members can explore a range of peer-reviewed research and clinical information published by the JAMA Network™, which brings JAMA^® together with JAMA Network Open and 11 specialty journals. Published continuously since 1883, JAMA is one of the most widely circulated, peer-reviewed, general medical journals in the world. If you are an AMA member or interested in becoming one, learn how to access these educational materials and innovative tools. 

“Beliefs About the Effect of Alcohol Use on Cancer Risk in the US Adult Population,” published in JAMA Oncology. The findings of this study highlight the persistence of misbeliefs and knowledge gaps about the link between alcohol and cancer among U.S. adults, which may contribute to the continuous increase in alcohol consumption. Individuals who drink alcohol were more likely to believe that alcohol consumption has no effect on cancer risk, which is alarming, given the growing burden of alcohol-related cancers in the U.S.

“An AI-Powered Lifestyle Intervention vs Human Coaching in the Diabetes Prevention Program,” published in JAMA. Among adults with prediabetes and overweight or obesity, referral to a fully automated AI-led Diabetes Prevention Program (DPP) was noninferior to referral to a human-led DPP in achieving a composite outcome based on weight reduction, physical activity, and HbA1c. Also read this editorial, “Artificial Intelligence and Diabetes Prevention.”

“Durability of 2024-2025 COVID-19 Vaccines Against JN.1 Subvariants,” published in JAMA Internal Medicine. The updated 2024–2025 COVID-19 vaccines provided effective protection, particularly against severe disease, although their effectiveness waned over time. Effectiveness against different subvariants was similar. Also read this invited commentary, “Evidence, Opinion, and Uncertainty About COVID-19 Vaccines.”

“Schizophrenia, Bipolar, or Major Depressive Disorder and Postacute Sequelae of COVID-19,” published in JAMA Network Open. In this cohort study of patients infected with COVID-19, patients with serious mental illness (schizophrenia, bipolar disorder, or recurrent major depressive disorder) compared with those without serious mental illness were at increased risk of postacute sequelae of SARS-CoV-2 (PASC), underscoring the need for coordinated mental health and COVID-19 care strategies. PASC is defined as ongoing, relapsing, or new symptoms or other health effects occurring after the acute phase of SARS-CoV-2 infection (i.e., that present 4 weeks or more after the acute infection).

“Health Service Use Among Young Adults With a History of Adolescent Cannabis Use,” published in JAMA Network Open. The findings of this birth cohort study indicated that early-onset and frequent cannabis use was associated with greater medical care utilization for both mental and physical health conditions in young adulthood. These findings support the relevance of delaying initiation and reducing intensity of cannabis use during adolescence.

The subscription cost of JAMA is included with your AMA membership, plus unlimited digital access to all JAMA Network journals, including: JAMA, JAMA Network Open, JAMA Cardiology, JAMA Dermatology, JAMA Internal Medicine, JAMA Neurology, JAMA Oncology, JAMA Ophthalmology, JAMA Otolaryngology–Head and Neck Surgery, JAMA Pediatrics, JAMA Psychiatry, and JAMA Surgery.

The online journals include many helpful features for students, residents and fellows, including full-text PDFs, clinical challenges, archived editions, audio and video author interviews where authors give their perspectives on a study’s objectives, findings and implications. 

There are several ways physicians can leverage resources from the JAMA Network to help them in their clinical practice:

• Take CME courses and earn AMA PRA Category 1 Credit™.
• Fulfill maintenance of licensure (MOL) and CME requirements on JN Learning™, the home for all JAMA Network CME.
• Read concise summaries of clinical guidelines and recommendations in a streamlined format designed for today’s busy physicians.
• Access one-page articles that present key facts in patient-friendly terms to support you and your patients.