We have long known that certain behaviors such as smoking and consumption of fatty foods lead to an increased risk of developing cancer. More recently, studies have isolated specific lifestyle decisions that may delay the onset of cancer or even reduce tumor formation in its early stages. Three examples are research on the impact of exercise on colon cancer in men, how aspirin consumption may negate the harmful effects of eating flame-broiled meat and a new link between child bearing and lung cancer.
Exercise and Colon Cancer
Exercising six days a week reduces the risk of colon cancer in men, according to a study by the Fred Hutchinson Cancer Research Center in Seattle. The study, conducted by Kristin Campbell, Ph.D.,and colleagues, illustrated the role of exercise in controlling abnormal cell growth in colon tissue.
In men who engaged in moderate to vigorous exercise for a year, more apoptosis (normal cell life and death cycles) was seen in crypt cells in the colon. More apoptosis is important because it means a lower likelihood that polyps and, ultimately, cancerous tumors would develop. "We saw a substantial increase in the potential for cellular apoptosis in areas of the colon most vulnerable to colon cancer," said Campbell. "The increase was most pronounced in men who exercised six hours a week. No change was seen in women, a finding that is consistent with our previous findings of altered proliferation in men, but not women. Therefore, physical activity may play a stronger role in colon cancer risk reduction among men than it does among women."
Flame-broiled Food and Aspirin
Another recent study addressed the question: is the association between flame-broiled food, meat consumption and breast cancer affected by aspirin use?
By studying the eating patterns of 312 women with breast cancer and 316 who were cancer free, Kala Visvanathan, M.B.B.S., of Johns Hopkins University and colleagues found that women who eat flame-broiled foods more that twice a month may be at increased risk of breast cancer, compared to women who don't usually eat foods prepared that way.
The good news, however, is that taking aspirin cancelled out the potentially harmful effects.
"We are not certain of the mechanism by which aspirin may be helping attenuate these risks. This is an area that further study should elucidate as we search for means to reduce the risk of breast cancer," said Visvanathan.
Childbirth and Lung Cancer
Women's reproductive behavior may affect their risk of lung cancer later in life, a study at the Harvard School of Public Health has found. Jessica Paulus, a graduate student in epidemiology, and colleagues studied data from 1,075 women with lung cancer and 867 cancer-free women who took part in a research study from 1992 to 2004 at the Massachusetts General Hospital in Boston. The researchers found that women who had one or more children had nearly a 40 percent lower risk of lung cancer compared to women without children. The more children a woman had, the lower her risk of lung cancer.
"Patterns of lung cancer incidence suggest that women may be at a greater risk of lung cancer than men," said Paulus. "Given the role of estrogen as a risk factor in other cancers, and the relationship between number of births and estrogen levels in the body, we hypothesized that having children may be associated with lung cancer risk in women."
While the researchers found a straight relationship between lung cancer and number of children, having one child did not significantly decrease the cancer risk compared to women who never had given birth. Having two children reduced the risk of cancer by 20 percent, and having three or more children reduced that risk by 40 percent.
All three of the above studies were presented at the American Association for Cancer Research's Frontiers in Cancer Prevention November, 2006 Research Meeting.