The message is everywhere: Exercise and stay at a healthy weight to cut your risk of cancer and other diseases. But do these steps pay off equally for everyone? What else can women do to improve their chances?
The experiences of hundreds of thousands of California women, documented through more than a decade’s worth of research, will help answer those sticky questions.
|Leslie Bernstein is principal investigator on the influential California Teachers Study. (Photo by Walter Urie)|
Led by Leslie Bernstein, Ph.D., director of City of Hope’s Division of Cancer Etiology, the California Teachers Study has shown how obesity, physical activity, diet and use of medications can influence women’s risk of breast and other cancers. Now, thanks to a new, $16.8 million grant from the National Cancer Institute, the study will uncover even more lessons about lifestyle and health.
Scientists will go deeper — not only into the steps women can take to reduce their risk, but also into how women’s genes might play a part. They hope their findings provide evidence for public health efforts that could help millions.
The study includes nearly 133,500 female teachers and administrators in the California public schools’ retirement system. Researchers started following them in 1995, asking them about their health status, height, weight and habits. Women have regularly provided a window into their lives, sharing information such as how much they exercise, whether they drink alcohol and if they used hormone therapy, oral contraceptives or other drugs.
In the coming years, researchers will home in on three areas that have seen a lot of change: women’s physical activity levels, obesity and aspirin use.
Getting plenty of exercise reduces the risk of breast and colon cancer, and potentially other cancers, too. But does everyone get the same benefit from a walk, jog or tennis class? According to Bernstein, certain genes associated with fitness, endurance and athletic ability might actually affect the benefit exercise provides to each woman — and whether women are physically active in the first place.
Many women today are struggling to lose their extra pounds. Obesity rates are rising, likely increasing future cancer rates, as well. Under the California Teachers Study, scientists will look at patterns of changes in body fat over a lifetime and how being obese or overweight is associated with common forms of breast, endometrial and colon cancers.
Disease risk stems from more than obesity, though. The researchers also will investigate how other factors like physical activity, hormone therapy and oral contraceptive use, eating and drinking habits, diabetes, smoking and menopausal status can interact with obesity to affect cancer risk.
Physicians today offer drugs like tamoxifen to help prevent breast cancer among breast cancer survivors and women at high risk for the disease, but these drugs offer little benefit for the average woman. They need options that are safe and inexpensive, and one possibility is aspirin.
Many women already take children’s aspirin to cut their risk of heart disease. With that in mind, the scientists hope to see whether aspirin can reduce breast cancer risk linked to the use of hormone therapy and other factors, and if it has effects on any type of breast cancer in particular.
Variations in genes related to inflammation, immune function and insulin resistance might also affect how aspirin use, obesity or physical activity influence breast cancer risk.
“We’re excited about this work, because we will be looking at risk factors that are modifiable,” Bernstein said. “These are steps that could help prevent cancer population-wide.”
Breast cancer risk reduction redux
Scientists have found a variety of factors that can affect women’s breast cancer risk. Among them:
- Age: Your breast cancer risk increases as you get older. Nearly 80 percent of women diagnosed with invasive breast cancer are 50 or older.
- Family history: Breast and ovarian cancer risk are greater among women with a close blood relative such as a mother or sister who has had these cancers.
- Genetics: Women with certain genetic mutations have greater breast and ovarian cancer risk than women who do not have these mutations.
- Race: Caucasian women are at slightly greater risk, although African-American women have lower survival rates.
- Obesity: Being overweight increases a woman’s risk of breast cancer.
- Breast density: Women with dense breast tissue have greater risk of breast cancer than other women, and cancers may be tougher to spot on mammograms.
- Reproductive issues: Women who have no children or had children at age 30 or older may be at slightly higher risk than other women; women who started menstruating early (before age 12) or entered menopause late (after age 55) also have a greater chance of developing breast cancer than those with later first menstrual period or those with earlier menopause.
- Alcohol: Breast cancer risk increases with the amount of alcohol consumed per day.
- Exercise: Regular physical activity (ideally, three to four hours a week) reduces breast cancer risk.
- Hormone therapy: Use of combined estrogen and progesterone therapy, prescribed for menopausal symptoms, can increase breast cancer risk.