As the world marks World Cancer Day, health experts are drawing renewed attention to a powerful but often overlooked fact: up to 40 per cent of all cancers are preventable.
The statistic, backed by global health authorities including the World Health Organization (WHO), highlights the roles of lifestyle choices, early detection, and public health policy in reducing the disease’s burden.
Cancer remains one of the leading causes of death globally and in Kenya, where cases have been rising steadily over the past decade.
According to the Ministry of Health, cancer is now the third leading cause of death in Kenya, after infectious and cardiovascular diseases, with tens of thousands of new cases diagnosed annually.
World Cancer Day, marked every year on February 4, is used to spotlight prevention, early diagnosis and access to care.
This year’s focus has reignited conversations around how many cancer cases could be avoided altogether through changes in behaviour and stronger health systems.
Health experts clarify that “preventable” does not mean cancer can be eliminated. Rather, it refers to cancers linked to modifiable risk factors that individuals, communities and governments can reduce or control.
The WHO and the International Agency for Research on Cancer (IARC) estimate that roughly four in ten cancer cases worldwide are caused by factors such as tobacco use, harmful alcohol consumption, unhealthy diets, physical inactivity, obesity, infections, air pollution and excessive exposure to ultraviolet radiation.
These are not random or unavoidable cancers but rather cancers that are strongly linked to behaviours, environments and exposures that can be addressed through prevention and early action.
Globally and locally, tobacco use remains the single largest preventable cause of cancer. Smoking is linked to cancers of the lung, throat, mouth, oesophagus and bladder.
In Kenya, tobacco use continues despite public health warnings, with both cigarettes and smokeless tobacco contributing to cancer risk.
Alcohol consumption is another major contributor. Studies show that alcohol increases the risk of cancers of the liver, breast, mouth and throat. Health experts warn that there is no completely safe level of alcohol consumption when it comes to cancer risk.
Poor diet, physical inactivity and obesity are also increasingly linked to cancers such as colorectal, breast and endometrial cancers. Urbanisation and sedentary lifestyles in Kenya have led to rising obesity rates, particularly in cities.
Infections play a significant role as well. Human papillomavirus (HPV) causes nearly all cases of cervical cancer, one of the most common cancers affecting Kenyan women.
Hepatitis B and C are linked to liver cancer, while Helicobacter pylori infection is associated with stomach cancer.
Air pollution, both outdoor and indoor, is another concern, especially in urban centres and households that rely on solid fuels for cooking.
Some of the most common cancers associated with preventable risk factors include:
- Lung cancer is largely linked to smoking and air pollution
- Cervical cancer, caused by HPV infection
- Liver cancer, linked to hepatitis infections and alcohol use
- Colorectal cancer, associated with diet, inactivity and obesity
- Breast cancer, influenced by alcohol use, obesity and physical inactivity
Health experts stress that prevention efforts targeting these cancers could save thousands of lives annually.
Prevention does not stop at lifestyle changes. Early detection and screening play a critical role in reducing cancer deaths.
Cancers detected at early stages are often easier and less costly to treat, with higher survival rates.
In Kenya, screening services for breast, cervical and prostate cancers are available, but uptake remains low due to factors such as fear, stigma, cost and lack of awareness.
Many patients still seek care when cancer is at an advanced stage, limiting treatment options.
Medical professionals emphasize that routine screenings, self-examinations and paying attention to warning signs can significantly improve outcomes.
Despite clear evidences, prevention remains difficult to implement.
Public health advocates argue that prevention must go beyond individual responsibility and include policy interventions, such as tobacco control laws, alcohol regulation, pollution reduction and expanded vaccination programmes.
Kenya has made strides in cancer prevention through HPV vaccination campaigns, tobacco control policies and the expansion of cancer treatment centres across counties.
However, more needs to be done to strengthen prevention messaging and make screening more accessible.
World Cancer Day serves as a reminder that reducing cancer cases requires a whole-of-society approach combining personal choices, community education and government action.
While not all cancers are preventable, experts agree that acting on known risk factors could dramatically reduce the number of new diagnoses.