University of Virginia Health System

More than appearances

Extra weight affects not just how you look; it increases your cancer risk

by Kathleen Phalen Tomaselli

Anyone who has struggled with extra weight has likely vowed to shed 20, 40, 60 pounds to fit in those favorite jeans or black dress. But few of us ever think, "If I don't lose these added pounds, I might die."

The reality is excess fat increases our risk of getting, and dying from, cancer. "This is not about cosmetics. I want people to be healthy," says Susan C. Modesitt, M.D., a University of Virginia Health System gynecologic oncologist (doctor specializing in female cancers), who is researching the connection between obesity and cancer in women.

 

why slim down

Recent research points to obesity (a body mass index of 30 or above) as a leading cause of cancer; by 2010 it's projected to outpace tobacco as the No. 1 preventable cause. "The current generation is the first generation who will not live as long as their parents," Modesitt says.

Heavier women are at increased risk for many cancers, including breast, colorectal, gallbladder, kidney, and, most notably, endometrial cancer of the uterine lining. This year, 40,000 women in the U.S. will be diagnosed as having endometrial cancer and almost 40 percent of those cases may be attributed to obesity.

Previously thought of as a cancer of postmenopausal women, about five percent of all endometrial cancers are now in women under 40. "We are seeing more women in their 20s and 30s with endometrial cancer and they often weigh about 300 pounds," Modesitt says. "This is a crisis on many levels."

 

why obesity leads to cancer

Adipose tissue (or body fat) is not just a repository for excess calories; it produces hormones. So the more body fat, the more hormones such as estrogen are produced. Normally, estrogen helps thicken a woman's uterine lining. If there is no pregnancy, this lining is sloughed off each month. Estrogen created from body fat goes unchecked and exposes heavier women to more circulating estrogen, causing the endometrial lining to get thicker and thicker. "This can become a cancer breeding ground," Modesitt says.

For heavier women with cancer, treatment is more difficult: they face increased risk of surgical complications, appropriate chemotherapy dosing has not been defined for them, and radiation therapy is more difficult to dose correctly.

 

why exercise matters

Nonetheless, not all women with endometrial cancer are obese and not all obese women will develop endometrial or other cancers. This suggests that other factors, aside from increased estrogen, play a role. The good news is initial research shows that overweight women who exercise have lower endometrial cancer rates.

In Modesitt's newest study, she is examining the hormone differences in adipose tissue of obese women with, and without, cancer. "The results of this study will enable doctors to identify which obese and overweight women are at increased risk for endometrial cancer, and hopefully, discover strategies that may counterbalance the detrimental effects of obesity," Modesitt says.

"My overall message to anyone struggling with their weight is to eat healthy, exercise, and have patience. Weight loss shouldn't be dramatic. Even a modest weight loss of five percent improves blood pressure and blood sugar. It's best to lose one to two pounds a week. If you have 100 pounds to lose, it will take a year but will definitely be worth the effort," she says. "Even small changes can make a big difference. Eliminating one soda a day for a year equals a ten-pound weight loss."

 

don't skip doctor check ups

The very weight that puts a woman at risk for disease and chronic conditions is often the main thing that keeps her from seeking the care she needs to stay healthy. Studies show that obese women are more likely than non-obese women to delay Pap tests, pelvic exams and mammograms. "They are embarrassed about their weight," says Susan C. Modesitt, M.D., a UVA Health System gynecologic oncologist. Here's why anyone who struggles with extra weight needs to see a healthcare professional regularly:

• Women gaining more than 20 pounds from age 18 to midlife double their risk of postmenopausal breast cancer, compared to women whose weight remains stable.
• For every 2-pound increase in weight, the risk of developing arthritis is increased by nine to 13 percent.
• A 5-foot, 5-inch woman, weighing 240 or more pounds, is 86 percent more likely to die within the next seven years than her normal-weight counterpart.
• Women more than 50 pounds overweight have a 10 times greater risk of endometrial cancer.
• Obese women have a 90-percent higher risk of getting kidney stones than non-obese women.
• Women who are obese during pregnancy are more likely to have gestational diabetes and problems with labor and delivery.

This article appeared in the summer 2008 issue of Vim & Vigor, a family health magazine sponsored by UVA Health System. If you don't already receive it at home, sign up today. It's free.