Putting knowledge to work
Exercise can help lower cancer risk.
The road to complete understanding of metabolic risks in cancer stretches far ahead; still, take-home messages are already emerging from the research. There's increasing emphasis on maintaining a healthy weight and avoiding diabetes, having an active lifestyle (moderate-to-vigorous physical activity at least 30 minutes a day, most days of the week), and eating a diet rich in fruits and vegetables (see Making sense of nutrition 'sound bites').
Dana-Farber research has shown that modifying metabolic factors can have important benefits during and after cancer treatment. For example, Fuchs and Jeffrey Meyerhardt, MD, MPH, reported in 2006 that colon cancer patients who exercised at moderate levels six to 12 months after surgery had a 50 percent higher survival rate than those who didn't exercise.
Jennifer Ligibel, MD, of the Women's Cancers Program at Dana-Farber, has been testing whether exercise lowers insulin levels in breast cancer survivors. "We know that women who are overweight at the time of diagnosis have a higher chance of recurrence than lean women, but the reasons for this are not clear," she says. "Recent evidence suggests that high insulin levels, which are common in overweight women, may be involved in the increased risk of breast cancer recurrence."
Ligibel led a study in which one group of breast cancer survivors did 16 weeks of cardiovascular and strength training while a comparable group had normal care. At the end of the experiment, the women who exercised had lowered their insulin measurements by almost 20 percent. "Exercise has benefits throughout treatment and beyond," Ligibel says. "It's an investment in a woman's health."
Much remains to be learned about the complex and crucial relationship of metabolic "lifestyle" factors and cancer risk. But as these studies show, the research has great potential for making a difference to individuals. Unlike other risk factors, such as age and family history, these can be modified with persistence, discipline, and knowledge emerging from the laboratory.
