Medications and lifestyle can lower breast cancer risk

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Mammography is a valuable tool for finding breast cancer when it is still limited to the breast and highly curable. But no matter how good the chances of survival are with early detection, I’m sure women would rather not develop breast cancer in the first place.

However, while 1 in 8 women will receive a diagnosis of breast cancer, today only a minority take advantage of proven lifestyle measures to reduce their chances of developing the disease, let alone take medications that can help prevent it. it in women with above-average risk.

Part of the problem may well be the confusion caused by frequent reports of conflicting evidence about what increases – or decreases – a woman’s chances of developing breast cancer, from the medications she uses to the foods and drinks she consumes.

Another inhibiting factor is the limited amount of time that clinicians can devote to assessing a woman’s risk of breast cancer and explaining the complex tradeoffs involved in preventing the disease.

In a report published in JAMA (Journal of the American Medical Association, in Portuguese) in 2020, experts from the University of California at San Francisco reviewed compelling evidence of two classes of drugs commonly prescribed after breast cancer treatment that may also help prevent breast cancer. cancer in some women not yet affected by the disease.

One class consists of two drugs, tamoxifen and raloxifene, that inhibit the action of estrogen in selective tissues. The other includes three aromatase inhibitors – anastrozole, exemestane and letrozole – that reduce circulating estrogen levels, which could stimulate the growth of estrogen-sensitive breast cancer.

Whether a woman can consider such drugs depends in part on her life choices and her medical history.

While some women prefer to ignore existing evidence and continue doing what they love, regardless of the associated risk, experts say they should at least be able to weigh their behavioral choices against an increased risk of breast cancer.

Their decisions should also consider their personal health history and the illnesses that run in their families, to which they may also be susceptible.

Alcohol consumption is a classic example. Even a small amount of alcohol — less than one drink a day — can increase the risk of breast cancer, and the more a woman drinks, the greater her chances of developing the disease. A friend recently treated for early-stage breast cancer stopped drinking wine, which resulted in weight loss, which can also reduce the risk of new or recurring breast cancer.

As far as smoking is concerned, there is no health benefit, only risk – to your breasts, as well as to all major organs and your life.

Another modifiable risk of breast cancer is being overweight, especially after menopause, when body fat becomes the main source of cancer-promoting hormones. The good news is that the two measures that can help reduce weight — a healthy diet and regular physical activity — also protect against breast cancer and reduce the risk of heart disease.

Strive to eat a diet based primarily on vegetables, fruits, whole grains, beans and nuts; healthy sources of fats like olive and canola oil; and fish instead of red meat. And include a weekly minimum of two and a half hours of moderate physical activity, or 75 minutes of vigorous activity, plus strength training twice a week.

Unfortunately, two long-known protective factors – early pregnancy (in the teens and 20s) and prolonged breastfeeding – run counter to the life goals of many modern women who want to pursue graduate degrees and professional advancement. as well as young women financially unable to support a family.

Many older women are faced with another confusing and controversial decision: whether and for how long to take hormone therapy to combat life-disrupting menopausal symptoms.

Except in the case of a previous history of breast cancer, current advice for women who have not had a hysterectomy is to take combined hormone therapy (i.e. estrogen and progestin) for as short a period as is necessary to control symptoms, but no longer than that a few years.

Another study, also published in 2020 in JAMA, described the long-term effects of breast cancer risk among 27,347 postmenopausal women randomly assigned to take or not take hormone replacement. The authors, led by Rowan T. Chlebowski at the University of California, Los Angeles Medical Center, reviewed the health status of the participating women more than two decades later.

Among 10,739 women who had no uterus and could safely take estrogen alone (progestin is normally added to prevent uterine cancer), menopausal hormone therapy reduced their risk of developing and dying from breast cancer. However, among the 16,608 women with a uterus who took combination hormone therapy, the incidence of breast cancer was significantly higher, although there was no increased risk of death from the disease.

Commenting on these results, Christina A. Minami, a breast cancer surgeon at Brigham and Women’s Hospital, and Rachel A. Freedman, an oncologist at the Dana-Farber Cancer Center, wrote that the new findings “should not lead to the use of hormone therapy with the sole objective of reducing the risk of breast cancer”.

But Freedman said in an interview, “If I’m counseling a patient who is really unhappy with menopausal symptoms and is an estrogen-only candidate, these findings ensure that her risk of breast cancer will not be higher over time.”

Then there is the possibility of taking a daily medication to suppress potential breast cancer in high-risk women who have not yet had the disease.

Dr. Jeffrey A. Tice, an internist at the University of California at San Francisco, suggested that women’s physicians use one of several risk-assessment calculators to determine a patient’s likelihood of developing breast cancer within the next five to ten years.

The US Preventive Services Task Force concluded that the benefits of medication outweigh the risks for postmenopausal women who are 3% or more likely to receive a diagnosis of breast cancer within five years.

Beginning in their 40s, younger women with a strong family history of breast cancer and those who have had precancerous results on a breast biopsy should consider preventive drug therapy, as Tice and Yiwey Shieh suggested in JAMA.

Tice said women in the 5% most at risk of breast cancer for their age can also weigh the benefit of preventive therapy and its possible risks, which could include blood clots or bone loss, depending on the drug used.

“Five years of therapy can reduce breast cancer risk by up to 20 years,” he reported.

Translated by Luiz Roberto M. Gonçalves

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