Having a doctor examine the breasts for potential signs of cancer may add little to the benefits of mammography screening, a large study suggests.

Researchers found that among nearly 62,000 women age 40 or older, the combination of mammography and a clinical breast exam detected only a small number of additional breast cancers compared with mammography alone.

Although the clinical exam did help catch cancers in women with dense breast tissue, in particular, it also put these women at greater risk of being told they might have cancer when they did not.

However, the findings should not be interpreted as a recommendation against clinical breast exams, according to the study’s lead author.

“We’re just trying to lay out the information for women,” said Dr. Nina Oestreicher, a researcher at Kaiser Permanente in Oakland, California.

“It’s really up to women and their doctors to make the decision,” she told Reuters Health, noting that many factors, including a woman’s personal risk of breast cancer and her degree of concern about the disease, could influence the choice to have regular clinical breast exams in addition to mammography.

Experts recommend that women at average risk of breast cancer have a mammogram every one to two years starting at age 40. Though mammography is imperfect, it is credited with reducing breast cancer death rates in a number of countries where the test is routinely performed.

However, the value of also having regular clinical breast exams, in which a doctor observes and feels the breasts for lumps and other abnormalities, has been unclear.

The new study, published in the American Journal of Roentgenology, suggests that much depends on the density of a woman’s breasts. Oestreicher and her colleagues found that clinical breast exams carried a greater benefit for women with more dense breast tissue, compared with those with more fatty tissue.

Dense breasts contain more glandular and connective tissue than fat, making it easier for tumors to be obscured on mammograms. So in some cases, palpating the breast for lumps can catch a tumor missed on the imaging test.

On the flip side, study patients with dense breasts were also nearly twice as likely to get a false-positive result from a clinical breast exam, which can lead to unnecessary biopsies.

According to Oestreicher, women should discuss these pros and cons of clinical breast exams with their doctors, then base their decisions on their own circumstances. For example, she noted, a woman who is particularly concerned about breast cancer may feel that the modest benefit of clinical breast exams is worth the possibility of getting a false alarm.

Since women with denser breasts benefit more from clinical exams, it might be helpful, Oestreicher said, for women to find out their breast density, which can be determined when they have a mammogram.

The current study included 61,688 women who had undergone at least one screening with mammography and a breast exam.

The researchers found that mammography detected 78 percent of the cancers in these women, while breast exams were able to catch 21 percent. The addition of a clinical exam to mammography picked up 25 cancer cases (4 percent) in addition to those detected by mammography alone.

SOURCE: American Journal of Roentgenology, February 2005.