Understanding Modifiable Risk Factors

Cancer is one of the leading causes of death worldwide. By 2050, global cancer deaths are projected to reach 18.5 million, a staggering 90% increase from the estimated 9.7 million deaths in 2022. This is not surprising, given that 35.3 million new cases are predicted in 2050, a 77% increase from the estimated 20 million new cases in 2022. The rapidly growing global cancer burden is attributable to factors such as population growth, an aging population, and changes in exposure to risk factors like tobacco, alcohol, obesity, and air pollution. Therefore, regular cancer screenings – even in the absence of symptoms – play a crucial role for early detection and treatment, which can help to save lives. The goal of cancer screening is to reduce mortality and morbidity through early detection and early treatment of cancer (e.g., breast screening), or to reduce the incidence of cancer by identifying and treating its precursor before disease progression (e.g., cervical screening). The following are the screening recommendations for the general population by various health organizations, for cancers with sufficient scientific evidence of effectiveness.

Tobacco use

Tobacco use is the single most preventable cause of cancer, responsible for approximately 1 in 4 cancer deaths worldwide, and affecting men at 3 times higher rates than women. Besides being the main cause of lung cancer (and accounting for 7 out of every 10 lung cancer deaths), it is also associated with 13 other types of cancer, including larynx, esophagus, throat, lips, mouth, liver, stomach, kidney, pancreatic, cervical, colorectal, breast, and prostate. Therefore, avoiding tobacco use and exposure to secondhand smoke are vital to cancer prevention. For smokers, they should quit smoking entirely by seeking evidence-based support like nicotine replacement therapy, counselling, and prescription medicines that can significantly improve success rates. While e-cigarettes (vapes) have been advertised as a smoking cessation aid in recent years, they can contain harmful substances, including cancer-causing chemicals that can be inhaled deep into the lungs.

Diet

A 2024 study published by the American Cancer Society (ACS) showed that while diet may statistically appear to play a small role in overall cancer risk – being linked to approximately 4% of all cancer cases and deaths, it can be a major risk factor in colon cancer. Up to 35% of all colorectal cancer cases are directly linked to dietary choices. Processed meat is the leading dietary risk factor for colorectal cancer, responsible for 12.8% of all cases and 14.6% among men. In women, the primary dietary contributor is low fiber intake, accounting for 11.8% of cases. Although no single food can guarantee cancer prevention, adopting a balanced diet that includes plenty of fiber- and antioxidant-rich foods like cruciferous vegetables, berries, and whole grains, while limiting the intake of red meats, processed foods, and sugary drinks, can greatly reduce the risk of developing cancer.

Physical activity

An estimated 3-5% of cancer cases are attributed to physical inactivity. Cancers such as female breast, colon, endometrial, and liver cancer have been linked to sedentary lifestyle. According to the ACS guidelines for cancer prevention, adults should engage in 150-300 minutes of moderate-intensity or 75-150 minutes of vigorous-intensity physical activity per week, or an equivalent combination of both. Interestingly, findings from a recent prospective cohort study of more than 85,000 adults in United Kingdom showed that daily physical activity, even at light intensities, is linked to lower cancer risk. The risk of developing cancer was 11% lower among individuals who took 7,000 steps daily and 16% lower among individuals who took 9,000 steps daily, compared to those who averaged 5,000 steps per day.

Body weight

Excess body weight (both overweight and obesity), is a known risk factor for a variety of cancers: esophagus, breast (postmenopausal women), colorectal, uterus, gallbladder, upper stomach, kidney, liver, ovarian, pancreas, thyroid, meningioma, and multiple myeloma. Overweight and obesity can lead to chronic inflammation and elevate the levels of insulin, insulin-like growth factors, and sex hormones, which may contribute to cancer development. Research has shown that the risk of cancer increases with both the amount of excess weight gained and the duration an individual remains overweight. To reduce the risk of cancer associated with excess body weight, individuals should follow a healthy dietary plan and engage in regular physical activity.

Alcohol consumption

All types of alcoholic beverages, including beer, wine and spirits, contain compounds that can increase chronic inflammation and damage DNA in the cells, even in small amounts. While studies have shown that moderate drinking may offer some cardiovascular benefits, there is no known safe level of alcohol consumption in relation to cancer risk. The risk starts at low levels and increases proportionately with the amount of alcohol consumed. Alcohol consumption is known to increase the risk of developing at least 7 types of cancer (oral cavity, oropharynx, larynx, esophagus, liver, colorectal, and female breast cancer). Additionally, individuals who use both alcohol and tobacco have a 5 times increased risk of developing cancers of the oral cavity, oropharynx, larynx, and esophagus, compared with those who use either alcohol or tobacco alone. Abstaining or reducing alcohol intake is a proactive step in decreasing cancer risk.

Ultraviolet exposure

Excessive exposure to ultraviolet (UV) radiation is one of the primary causes of skin cancer, and is associated with approximately 65% of melanoma cases, and 90% of non-melanoma skin cancers, including basal cell carcinoma and squamous cell carcinoma. Since UV radiation can damage the DNA in the skin cells, skin protection from UV radiation is critical in reducing skin cancer risk. This can be achieved by using sunscreen with a high sun protection factor (SPF), even on cloudy days, and wearing protective clothing like hats, sunglasses, and long sleeves. Importantly, avoid being outdoors in open areas during peak sunlight hours (between 10AM to 4PM), as well as using tanning beds. While some cancer risk factors are beyond our control, modifiable risk factors offer an opportunity for individuals to take charge of their health and reduce their likelihood of developing cancer. Making lifestyle changes such as quitting smoking, having a balanced nutrient-rich diet, staying physically active, maintaining a healthy body weight, limiting alcohol intake, and protecting from excessive exposure to UV radiation can make a significant difference in lowering cancer risk and enhancing quality of the life.