# What are the common risk factors and prevention strategies for cancer?

Cancer is a group of diseases that involve abnormal cell growth with the potential to invade or spread to other parts of the body. It is one of the leading causes of death worldwide, accounting for nearly 10 million deaths in 20201. However, many cancers can be prevented by avoiding or reducing exposure to known risk factors and by adopting healthy lifestyles.

## Risk factors for cancer

Risk factors are anything that can increase the chance of developing cancer. Some risk factors are modifiable, meaning they can be changed or controlled, while others are non-modifiable, such as age, gender, and family history. Some of the common modifiable risk factors for cancer are:
– **Tobacco use**: Tobacco smoke contains more than 7000 chemicals, many of which are carcinogenic (cancer-causing). Tobacco use is the single greatest avoidable risk factor for cancer mortality and kills more than 8 million people each year, from cancer and other diseases2. Tobacco use can cause cancers of the lung, mouth, throat, larynx, esophagus, stomach, pancreas, kidney, bladder, cervix, and blood.
– **Alcohol consumption**: Alcohol is a toxic, psychoactive, and dependence-producing substance that can damage the cells and tissues of the body. Alcohol is a Group 1 carcinogen that is causally linked to 7 types of cancer, including esophagus, liver, colorectal, and breast cancers. Alcohol consumption is associated with 740 000 new cancer cases each year2. The risk of cancer increases with the amount of alcohol consumed.
– **Overweight and obesity**: Excess body weight can affect the hormones, inflammation, and immune system of the body and increase the risk of developing various types of cancer such as esophagus, colorectal, breast, endometrial and kidney. Excess body mass was responsible for 3.4% of cancers in 2012, including 110 000 cases of breast cancer per year2.
– **Physical inactivity and unhealthy diet**: Lack of physical activity and consumption of unhealthy foods can contribute to overweight and obesity and increase the risk of cancer. Physical activity can help regulate the hormones, metabolism, and immune system of the body and lower the risk of cancer. A healthy diet that includes plenty of fruits, vegetables, lean proteins, healthy fats, and whole grains can provide the nutrients and antioxidants that can protect the cells from damage and reduce the risk of cancer.
– **Exposure to harmful chemicals**: Some chemicals in the environment or in the workplace can cause mutations or damage to the DNA of the cells and increase the risk of cancer. These include asbestos, benzene, arsenic, radon, formaldehyde, and some pesticides. Exposure to these chemicals can be avoided or reduced by following safety guidelines and regulations.
– **Exposure to ultraviolet (UV) radiation**: UV radiation from the sun or artificial sources such as tanning beds can damage the DNA of the skin cells and cause skin cancers such as melanoma and basal cell carcinoma. Exposure to UV radiation can be avoided or reduced by wearing protective clothing, hats, sunglasses, sunscreen, and avoiding peak hours of sun exposure.
– **Infections**: Some viruses and bacteria can infect the cells and cause chronic inflammation or interfere with the immune system. These include human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV), Helicobacter pylori (H. pylori), Epstein- Barr virus (EBV), human immunodeficiency virus (HIV), human T-cell leukemia virus type 1 (HTLV-1), Kaposi sarcoma-associated herpesvirus (KSHV), and Merkel cell polyomavirus (MCV). These infections can cause cancers such as cervical, liver, stomach, lymphoma, sarcoma, and skin cancers. Infections are responsible for up to 25% of cancer cases in low- and middle-income countries2.

## Prevention strategies for cancer

Cancer prevention is action taken to lower the risk of getting cancer. Prevention offers the most cost-effective long-term strategy for the control of cancer. According to WHO2, some of the prevention strategies for cancer are:
– **Not using tobacco**: Quitting smoking or never starting is one of the most important ways to prevent cancer. Tobacco cessation programs and policies can help smokers quit or reduce their tobacco use.
– **Limiting alcohol consumption**: Reducing or avoiding alcohol consumption can lower the risk of cancer. Alcohol consumption guidelines and policies can help people limit their alcohol intake.
– **Maintaining a healthy body weight**: Achieving and maintaining a healthy body weight can lower the risk of cancer. Body mass index (BMI) and waist circumference can be used to measure body weight and fat distribution. A healthy BMI is between 18.5 and 24.9 kg/m2, and a healthy waist circumference is less than 94 cm for men and less than 80 cm for women.
– **Eating a healthy diet**: Eating a healthy diet can lower the risk of cancer. A healthy diet should include at least 400 g of fruits and vegetables per day, limit the intake of red and processed meats, salt, sugar, and saturated and trans fats, and increase the intake of dietary fiber, whole grains, nuts, seeds, legumes, and fish.
– **Doing physical activity on a regular basis**: Doing physical activity on a regular basis can lower the risk of cancer. Physical activity can be moderate or vigorous, depending on the intensity, duration, and frequency. Moderate physical activity is defined as any activity that causes a slight increase in breathing and heart rate, such as brisk walking, cycling, or gardening. Vigorous physical activity is defined as any activity that causes a large increase in breathing and heart rate, such as running, swimming, or playing sports. Adults should do at least 150 minutes of moderate physical activity or 75 minutes of vigorous physical activity per week, or a combination of both.
– **Getting vaccinated against HPV and HBV**: Vaccines are available for HPV and HBV, which can prevent cervical and liver cancers, respectively. HPV vaccine is recommended for girls and boys aged 9 to 14 years, before they become sexually active. HBV vaccine is recommended for infants within 24 hours of birth, followed by two or three doses in the first year of life.
– **Scheduling screenings**: Screenings are tests or exams that can detect cancer or precancerous changes in the body before they cause symptoms or become invasive. Screenings can help prevent cancer by allowing early detection and treatment. Some of the common screenings for cancer are:
– Pap smear: A test that collects cells from the cervix and examines them for abnormal changes that may indicate cervical cancer or precancerous lesions. Pap smear is recommended for women aged 21 to 65 years, every three to five years depending on the age and risk factors.
– Mammogram: An X-ray of the breast that can detect breast cancer or precancerous lesions. Mammogram is recommended for women aged 50 to 74 years, every two years depending on the age and risk factors. – Colonoscopy: A procedure that uses a flexible tube with a camera to examine the inside of the colon and rectum for polyps or tumors that may indicate colorectal cancer or precancerous lesions. Colonoscopy is recommended for adults aged 50 to 75 years, every 10 years depending on the age and risk factors.

## Conclusion

Cancer is a major public health problem that affects millions of people worldwide. However, many cancers can be prevented by avoiding or reducing exposure to known risk factors and by adopting healthy lifestyles. By following the prevention strategies mentioned above, you can lower your risk of cancer and improve your overall health and well-being.

## References

: National Cancer Institute (NCI). Physical Activity and Cancer [Internet]. Bethesda: NCI; [updated 2016 Nov; cited 2023 Jul 5]. Available from
(1) Cancer Causes and Prevention – NCI – National Cancer Institute. https://www.cancer.gov/about-cancer/causes-prevention (2) Preventing cancer – World Health Organization (WHO). https://www.who.int/activities/preventing-cancer (3) Cancer prevention: 7 tips to reduce your risk – Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/cancer-prevention/art- 20044816 (4) Cancer – World Health Organization (WHO). https://www.who.int/news-room/fact-sheets/detail/cancer