Common cancer risk factors that should not be ignored

Cancer is one of the leading causes of death worldwide, but health experts say many cancer cases are linked to preventable risk factors.

The World Health Organisation (WHO) estimates that cancer caused nearly 10 million deaths globally in 2024, accounting for almost one in six deaths worldwide. It says about 38 per cent of cancers can currently be prevented by avoiding known risk factors and implementing evidence-based prevention strategies.

Cancer continues to affect thousands of families in Nigeria every year. According to WHO, an estimated 130,000 new cancer cases were diagnosed in 2022, with 80,000 deaths.

While cancer can result from several factors, including genetic changes, age and environmental exposures, some established risks are linked to infections, substances and behaviours that can be prevented.

In a recent health awareness video, Nigerian physician and health communicator, Chinonso Egemba, popularly known as Aproko Doctor, highlighted some of these risks, including hepatitis B, aflatoxin, tobacco, alcohol and human papillomavirus (HPV).

Hepatitis B

According to Aproko Doctor, hepatitis B is particularly dangerous because it can remain in the body without obvious symptoms while damaging the liver.

“When it goes untreated and untested, it’s a virus that starts attacking your liver. Many Nigerians currently are living with it right now, and many of them don’t know because it can sit quietly inside your body for years without a single symptom,” he said.

His warning is supported by WHO, which says chronic hepatitis B infection can cause cirrhosis and liver cancer.

WHO estimates that 240 million people were living with chronic hepatitis B globally in 2024, with the infection contributing to about 1.1 million deaths, mainly from cirrhosis and hepatocellular carcinoma, the most common type of primary liver cancer.

Hepatitis B is preventable through vaccination. WHO recommends hepatitis B vaccination as an important measure for preventing infection and its long-term complications.

Aflatoxin in food

Aproko Doctor warned that the cancer risk can begin with improperly stored food.

“Aflatoxin is basically a poison produced by fungus,” he explained, noting that it can contaminate foods such as grains and groundnuts when they are poorly stored.

According to WHO, Aflatoxins are a group of poisonous mycotoxins produced by certain moulds (Aspergillus species) that contaminate food crops and pose severe health risks like liver cancer. They are toxins produced by certain moulds and can contaminate crops including maize, sorghum, rice and groundnuts. Exposure to aflatoxins can cause liver cancer.

WHO advises discarding food that appears mouldy, discoloured, or shrivelled because mycotoxins can penetrate beyond the visibly affected part.

Aflatoxin exposure can also be particularly dangerous in people infected with hepatitis B. The WHO/FAO Joint Expert Committee on Food Additives says hepatitis B infection is an important contributor to the ability of aflatoxins to cause liver cancer.

This means food storage and handling can also form part of cancer prevention, particularly in communities where grains and other foods are stored for long periods in warm or damp conditions.

Tobacco smoking

Tobacco remains one of the most established cancer risks.

“Smoking generally, as long as you light it with fire and put it on your body, increases the risk of cancer, especially tobacco smoke,” Aproko Doctor said.

He added that the danger was not limited to lung cancer because tobacco smoke contains cancer-causing chemicals that can damage cells throughout the body.

WHO says tobacco smoke contains more than 7,000 chemicals, at least 69 of which are known to cause cancer. Tobacco use is the world’s single greatest avoidable risk factor for cancer mortality.

Smoking can cause cancers of the lung, mouth and throat, oesophagus, bladder, kidney, liver, pancreas, stomach, colon and rectum, cervix and blood, among others.

Alcohol

Alcohol is another established cancer risk. WHO confirms that alcohol consumption increases the risk of several cancers, including cancers of the mouth, throat, oesophagus, liver, colorectum and breast.

WHO also says no level of alcohol consumption can be considered risk-free in relation to cancer.

“The more alcohol you drink, the higher the risk. However, how much and how fast the risk from drinking alcohol increases differs by cancer type,” it noted.

The global body explained that alcohol increases the likelihood of developing certain cancers, with the risk influenced by the amount consumed and other factors.

Human papillomavirus

According to Aproko Doctor, the virus is common, and some types can cause cancer, particularly cervical cancer.

“In women, this particular HPV is responsible for cervical cancer,” he noted.

According to the WHO, persistent infection with high-risk HPV types causes nearly 99 per cent of all cervical cancer cases. HPV is also associated with cancers of the vulva, vagina, anus, penis and mouth and throat.

Although HPV infection is very common, not everyone infected with the virus will develop cancer. WHO says about 90 per cent of HPV infections are controlled naturally by the body, while persistent infection with high-risk types can lead to cancer.

WHO recommends a complete three-step strategy to stop cervical cancer through vaccination, screening, and treatment.

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Preventing Cancer

A 2026 global analysis by WHO and its International Agency for Research on Cancer (IARC) estimated that 37 per cent of all new cancer cases diagnosed globally in 2022, about 7.1 million cases, were linked to preventable causes.

Tobacco was the leading preventable cause, accounting for 15 per cent of all new cancer cases, followed by cancer-causing infections at 10 per cent and alcohol at three per cent.

WHO recommends avoiding tobacco, reducing or avoiding alcohol, maintaining a healthy weight, eating a healthy diet, engaging in regular physical activity and receiving recommended vaccinations against cancer-causing infections such as hepatitis B and HPV.

As Aproko Doctor noted, understanding the risks is an important first step.“Don’t let anybody deceive you. Say no to smoking in any form,” he said.