Reduce cancer burden by being more physically active: Call out for everyone;more so for girls and women

The increase in the burden of cancers is a challenge to the health system of every country, irrespective of the resources available; in terms of infrastructure, advanced technology or trained human resource. The International Agency for Research on Cancer, which is the agency of World Health Organisation for cancer research, predicts a 77% increase in global incidence of cancer by 2050; in comparison with the data from 2022 ¹ . The increase in cancer burden is not uniform across all countries. The absolute increase in the incidence of cancer cases will be more in countries with high Human Development Index (HDI); on the contrary, the proportionate increase in incidence will be the highest in countries with low HDI (142%) and moderate HDI (99%) ¹ . More importantly, the predicted increase in mortality in these countries will be huge, nearing 200%. Lung cancer is the leading cause of cancer death, globally, followed by colorectal, liver, breast and stomach cancers. Among women, breast cancer is the most common cancer and the leading cause of cancer mortality; while lung and colorectal cancers are in the second and third positions. Lung cancer is the commonest cancer and the leading cause of cancer mortality among men. Prostate and colorectal cancers are the second and third most commonly occurring cancers in men, while liver and colorectal cancers are the second and third most common causes of cancer death among men ¹ . Cervical cancer, which is preventable by vaccination, continues to be in the eighth position in terms of burden and ninth in terms of mortality. Prevention and control of tobacco and alcohol use, promoting healthy diet and enhancing physical activity are the major interventions in cancer prevention.

There are inequities in access to diagnosis and treatment in almost all types of cancers. These inequities are most pronounced in breast cancer. Women in low income countries are 50% less likely to be diagnosed, while they are more likely to die from breast cancer due to delay in diagnosis and inadequate access to quality treatment. In countries with high HDI, probability of diagnosis of breast cancer is 1 in 12, while in those with low HDI, it is 1 in 27; the risk of mortality in breast cancer patients in high HDI settings is 1 in 71 while it is 1 in 48 in low HDI settings ¹ .

In this background, investing in the prevention of cancers should be a top priority. There is steady increase in the body of evidence on the protective effects of moderate physical activity in preventing cancers. The risk reduction by enhanced physical activity is evident in common cancers such as bladder, breast, colon, endometrial, renal and gastric cancers ² . Physical activity at the younger age groups reduces the risk of both breast cancer and colon cancer ³ . Evidence synthesis demonstrates different pathways through which moderate exercise prevents breast cancer. These are the variations in the circulating insulin, adipokines and estrogen levels, inflammation and oxidative stress ⁴ . Moderate exercise reduces proinflammatory markers, reprogrammes the tumour microenvironment and generates exercise induced myokines, which reduces the risk for breast cancer. A combination of aerobic exercise and resistance exercise reflects in the biomarker levels and benefits in both prevention and improvement in clinical outcomes and survival in breast cancer. Physical activity benefits women both in the premenopausal and postmenopausal age groups. Plasma levels of sex hormones-binding globulin (SHBG) will be low in obese women in both premenopausal and postmenopausal age groups; high intensity physical activity decreases the circulating level of estradiol in premenopausal women.

American Cancer Society recommends 150-300 minutes of moderate-intensity aerobic activity or 75–150 minutes of vigorous aerobic activity, or an equivalent combination, every week. Children and adolescents would need one hour of moderate or vigorous intensity activity each day, with vigorous intensity activity at least 3 days each week. There is molecular, clinical and public health evidence in favour of protective effect of moderate exercise; we need to work further to provide a facilitating environment for the general population to undertake moderate physical activity. Countries like India need further implementation research to translate the evidence into policies and programmes so that moderate physical activity becomes part of everyone’s daily routine. Implementation research has the design advantage to capture the contextual factors to increase uptake of this complex behavioural intervention ³ . The settings can be school, workplace, hospitals or the community. Within the clinical settings, it is high time that we screen for physical inactivity using tools like the Simple Physical Activity Questionnaire (SIMPAQ) ⁵ . We need to flag physical inactivity as an important risk factor and start interventions.