Scientists find links between chronic disease, cancer

A team of researchers in the US and Taiwan have found links between eight common chronic diseases and cancer and five unhealthy lifestyle factors including smoking, insufficient physical activity, insufficient fruit and vegetable intake, alcohol consumption, and obesity.

The team found that several common chronic diseases account for more than a fifth of new cancer cases and more than a third of cancer deaths.

The results were published on Jan 31 in The BMJ (formerly the British Medical Journal).

The study was led by Wu Xifeng, a professor at MD Anderson Cancer Center in Houston; Chi Pang Wen, professor at National Health Research Institutes in Taiwan; and Chwen Keng Tsao of MJ Health Management Institution in Taiwan. The first author is Tu Huakang, postdoctoral fellow at MD Anderson.

The researchers set out to investigate the combined effect of eight common chronic diseases or disease markers — for example, high blood pressure as a marker of heart disease — on cancer risk compared with lifestyle factors.

The study involved 405,878 men and women in Taiwan with no history of cancer. They completed a questionnaire on medical history, lifestyle, and demographic information and underwent a series of medical tests between 1996 and 2007. Weekly leisure time physical activity was also measured, according to the team's news release.

Participants were followed for about eight years.

The researchers found that cardiovascular disease, diabetes, chronic kidney disease, pulmonary disease and gouty arthritis were individually associated with the risk of developing cancer or cancer death.

Higher chronic disease risk scores were linked with an increased risk of developing cancer and cancer death, with the highest levels associated with a more than twofold increase in the risk of developing cancer and a fourfold increase in the risk of cancer death.

High chronic disease risk scores were also associated with substantial reduction in life span. The highest scores were associated with 13.3 years of life lost in men and 15.9 years of life lost in women.

The findings in chronic diseases and lifestyle factors can help doctors treat patients more efficiently, said Tu.

"Researchers have found that cancer is the number one feared disease for most people, yet they tend to be reluctant to take active measures to control and treat chronic diseases. This finding should give doctors tools to help patients to realize the seriousness of chronic conditions," said Tu.

The researchers also explored whether physical activity could reduce the cancer risk associated with chronic diseases and disease markers.

They found that physical activity was associated with a nearly 40% reduction in the excess risks of cancer and cancer death associated with chronic diseases and markers.

"This finding tells people that inactivity is unhealthy, and adequate exercise is greatly beneficial," Tu said.

These results suggest that chronic disease "is an overlooked risk factor for cancer," write the authors, and that physical activity "is a promising approach to reduce the cancer risk associated with chronic diseases and markers." 

The findings have important implications for developing new cancer prevention strategies and improving the management of chronic diseases, they conclude.

The team will continue to monitor the cohort and new research topics will develop accordingly, Tu said.