A large proportion of cancer cases and deaths among U.S. individuals who are white might be prevented if people start following a healthy life style.
Cancer is a leading cause of death in the United States. Mingyang Song, of Massachusetts General Hospital, Harvard Medical School and the Harvard T.H. Chan School of Public Health, Boston, and Edward Giovannucci, of the Harvard T.H. Chan School of Public Health and Harvard Medical School, Boston, analyzed data from two study groups of white individuals to estimate the proportion of cases and deaths of carcinoma among whites in the United States that can be potentially prevented by lifestyle modification.
A total of 89?571 women and 46?339 men from 2 cohorts were included in the study: 16?531 women and 11?731 men had a healthy lifestyle pattern (low-risk group), and the remaining 73?040 women and 34?608 men made up the high-risk group.
A healthy lifestyle pattern was defined as never or past smoking, no or moderate alcohol drinking, BMI of at least 18.5 but lower than 27.5, and weekly aerobic physical activity of at least 75 vigorous-intensity or 150 moderate-intensity minutes. Participants meeting all 4 of these criteria made up the low-risk group; all others, the high-risk group.
Within the 2 cohorts, the PARs for incidence and mortality of total carcinoma were 25% and 48% in women, and 33% and 44% in men, respectively. Also, for individual cancers, the respective PARs in women and men were 82% and 78% for lung, 29% and 20% for colon and rectum, 30% and 29% for pancreas, and 36% and 44% for bladder. The PARs were 4% and 12% for breast cancer incidence and mortality, and 21% for fatal prostate cancer.
The authors note that including only white individuals in their PAR estimates may not be generalizable to other ethnic groups but the factors they considered have been established as risk factors in diverse ethnic groups too.
How does physical activity prevent cancer?
In women, physical activity can lower the level of oestrogen. Oestrogen is thought to fuel the development of many breast and womb cancers, so reducing the levels of this hormone could help to reduce the risk.
Activity can also reduce the amount of insulin in our blood. Insulin is very important in controlling how our bodies use and store energy from food. Changes in insulin levels can have effects all over the body. And scientists think insulin can turn on signals that tell cells to multiply. Because cancer starts when cells multiply out of control, lowering insulin levels could help stop some types of cancer from developing.
As a society, we need to avoid procrastination induced by thoughts that chance drives all cancer risk or that new medical discoveries are needed to make major gains against cancer, and instead we must embrace the opportunity to reduce our collective cancer toll by implementing effective prevention strategies and changing the way we live.