Cancer Care

Four times a week, Anne Rinn, 28, a psychology professor in Bowling Green, Ky., whose mother died of breast cancer, goes to kickboxing, aerobics or Pilates classes. Liz Usborne, a 64-year-old breast-cancer survivor, lobs tennis balls over the net and circuit-trains at a women’s gym near her home in Bonita, Calif. The thread binding them? Concern about getting—or surviving and thriving after—breast cancer.

The American Cancer Society estimates that this year, 241,000 women will learn they have breast cancer and 40,000 women will die of it. Fortunately, a growing list of effective therapies developed during the past decade has helped extend lives, one reason that deaths from breast cancer have been dropping slowly since 1990. Living among us are more than 2 million women who have undergone breast-cancer treatments.

Modern miracle drugs like tamoxifen and raloxifene routinely cut risk for breast cancer in women whose medical histories or genes make them especially vulnerable to it. But reams of research also suggest that exercise—an activity as old as the human race—substantially reduces the odds of ever getting the disease, lengthens survival and considerably enhances quality of life for women with breast cancer.

Scientists don’t completely understand why exercise is so important, but they’re actively looking for answers. Roughly two thirds of all breast cancers are considered estrogen-positive; that means that the hormone estrogen fuels their growth. The rest are estrogen-negative. Many experts believe regular exercise lowers the amount of estrogen circulating through the body in the bloodstream. So for certain types of breast cancer, less estrogen equals less fuel. Exercise also pares off hormonally active fat tissue. Fat manufactures a substance called aromatase that converts hormones known as androgens to estrogen. After menopause, when the ovaries stop cranking out high levels of estrogen, this hormonal cascade becomes the major source of estrogen in a woman’s body.

Recently two large, carefully designed studies suggested exercise may work through more than just hormonal mechanisms linked to estrogen. In a study published last month in the Archives of Internal Medicine, researchers speculated that exercise might affect tumor aggressiveness. The researchers found that long-term moderate or strenuous activity over a lifetime cut risk for developing estrogen-negative invasive breast cancers (though not estrogen-positive cancers). Since fewer therapies are effective against estrogen-negative cancers, that’s heartening news. Some earlier research on exercise suggests it lowers risk for estrogen-positive cancers, too. Scientists are also looking beyond estrogen at the effects exercise has on insulin, leptin and certain growth factors.

Regular exercise early in life, particularly around puberty, and exercise vigorous enough to suppress other reproductive hormones may make a difference, too. A 2005 multicenter study on lifetime activity matched more than 4,000 white and black breast-cancer survivors with controls. Researchers found a 20 percent decrease in breast-cancer risk for the most versus least active women.

Source : www.newsweek.com