For years, the American Cancer Society has recommended monthly breast self-examination (BSE) for women age 20 and older to aid in the early detection of breast cancer. The Society’s guidelines have been updated, and BSE is now optional.

The shift is sure to be controversial, as there are various groups and individuals who believe breast self-exams are important to women’s health. But expert opinion is divided on whether there is a benefit to BSE, said Debbie Saslow, PhD, director of breast and gynecologic cancer for ACS.

Recent studies, including a trial with more than 250,000 women in Shanghai, China, have not shown that BSE reduces deaths from breast cancer.

“We don’t think there’s a strong reason not to do BSE, but there’s no strong reason to do it, either. BSE is an option for women starting in their 20s,” Saslow said.

Under the new guidelines, BSE is being recognized as a way for women to know how their breasts normally feel and to notice any changes. This approach focuses on the importance of self awareness compared to early detection.

“There are two ways to think about breast self-examination,” said Amy Langer, executive director of the National Alliance of Breast Cancer Organizations (NABCO). “One is as a particular technique that has to be learned, has to be demonstrated, has to be practiced and done consistently and correctly.”

Most women don’t do BSE in that structured, formal way, Langer said, because they don’t have confidence that they’re doing it right -- and that makes them feel anxious.

“Another way to think of BSE … is being familiar with the landscape of your breasts. It’s knowing that you already have a bump here, a wrinkle there, and that that freckle by your nipple has always been there, so that you get a sense in your mind and in your hands of what feels normal for you,” Langer said. “That’s less overwhelming for women.”

One of the main reasons for the change to the BSE guideline is the lack of evidence over the benefits of breast self-examination.

Mammography is so far the only screening method that has been consistently proven to reduce deaths from breast cancer. It is considered the gold standard of screening, while BSE is, at best, a supplement to regular mammograms and breast exams by a doctor.

While a number of earlier studies found that BSE helped women detect cancers earlier, most of those studies were conducted before mammography was available as a screening tool. However, even in those studies, many of the women who detected their own cancers did not find them while performing BSE; they found them incidentally, while dressing or bathing, for instance.

And as mammography has become more common, the number of cancers detected by women themselves has dropped.

“An increasing number of cancers are detected at early stages, at a size that is too small to be found not only by BSE, but by a clinical exam,” said Langer, who is herself an 18-year breast cancer survivor.

A breast lump has to be about one inch in diameter, or about the size of a quarter, for a woman to feel it herself. A mammogram can reveal an abnormality as small as a pencil eraser.

Moreover, teaching and promoting BSE takes up numerous resources that may be better used to promote mammography, which has proven life-saving benefits, Saslow said.

Another potential problem is the guilt many women feel because they don’t do regular BSE. Such guilt is misplaced, said Saslow, because evidence is lacking that BSE has benefits beyond self awareness.

Breast cancer is the most common form of cancer in American women. The American Cancer Society estimates that more than 200,000 women will be diagnosed with it this year, and nearly 40,000 will die from it. The disease is rare in women under age 40.

Although there are things women can do to lower their risk of developing breast cancer (eating right, exercising, maintaining a healthy body weight, staying away from alcohol), no one yet knows how to prevent the disease.

“We can’t prevent it, but what we can do is increase the odds it will be diagnosed early,” said NABCO’s Langer, emphasizing the importance of promptly reporting any breast changes to a doctor.