Cigarette smoking was by far the leading risk factor, contributing to nearly one in five cancer cases and about a third of all cancer deaths.
The findings were published this month in the journal CA: A Cancer Journal for Clinicians.
In 2019, these lifestyle factors were linked to nearly 715,000 cancer cases and about 262,000 deaths.
The findings are not exactly new, but they add to mounting research that shows many cancer cases – and as many as half the deaths – can be prevented with lifestyle changes.
The finding underscores the importance of comprehensive tobacco control policies to stop smoking, and the need to boost screening for early detection of lung cancer, when treatment could be more effective, he added.
Despite the findings that people have more control than they think over their cancer risk, there are still many questions about who gets cancer and why.
Experts say some risk factors including obesity and a lack of physical activity could be playing a role but they still do not know what’s causing the jump in cases among younger adults.
In Hong Kong, the Cancer Registry recorded 38,462 cancer cases in 2021, the most recent year for which statistics are available. There were 5,978 cases of lung cancer, 5,899 cases of colon cancer, 5,592 of breast cancer, 3,038 of prostate cancer, 1,771 of liver cancer and 1,306 of stomach cancer. That year, 15,108 people died of cancer.
In this new ACS study, researchers used nationally representative data on cancer incidence and mortality and risk factor prevalence to estimate the proportion and number of cancer cases and deaths attributable to potentially modifiable risk factors overall for 30 cancer types.
“These findings show there is a continued need to increase equitable access to preventive healthcare and awareness about preventive measures,” added Dr Ahmedin Jemal, senior vice-president, surveillance and health equity science at the American Cancer Society and senior author of the study.
Additional reporting by staff reporter