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Study Finds Risk of Breast Cancer Not Equal for Both Breasts (dateline April 29, 2003)

A newly published study finds that women who are diagnosed with the pre-cancerous condition lobular carcinoma in situ (LCIS) are more likely to develop breast cancer in the breast with LCIS than in the other breast. Experts had previously believed that women with LCIS were at equal risk of developing breast cancer in either breast, which led to some women deciding to undergo preventive bilateral mastectomies to remove both breasts. This latest study shows that that option may not be necessary.

Lobular carcinoma in situ (LCIS), also called lobular neoplasia, is a sharp increase in the number, appearance, and abnormal behavior of cells contained in the milk-producing lobules of the breast. Though LCIS is not considered a cancer, women who are diagnosed with LCIS are at a higher risk of developing breast cancer later in life. According to the National Cancer Institute, a woman with LCIS has a 25% chance of developing some form of invasive cancer within her lifetime.

Currently, treatment decisions for women diagnosed with LCIS are typically based on the idea that the risk of breast cancer is equal in both breasts. To determine whether this belief is valid, David L. Page, MD and his colleagues from Vanderbilt University Medical Center in Nashville, Tennessee studied 252 women who had undergone 261 surgical biopsies that revealed LCIS from 1950 to 1985. None of the women received treatment for LCIS (such as the drug tamoxifen, preventive mastectomy, etc.).

Twenty percent of the women with LCIS later developed breast cancer, according to the researchers. Of those women, nearly 70% were diagnosed with the cancer in the same breast as the LCIS was found. Thus, Dr. Page and his team concluded that breast cancer is three times more likely to occur in the same breast as LCIS in patients who have a history of the pre-cancerous condition.

This means that a drastic option for preventing breast cancer, preventive bilateral mastectomy, may not be the most viable choice for women with LCIS since the risk of breast cancer is much higher in one breast than the other. Some women with LCIS who are at very high risk of developing breast cancer, considering multiple factors such as family history or gene status, choose to have both breasts removed as a precaution. However, Dr. Page suggests that removing the breast tissue area with LCIS may be sufficient. This, as well as other options, should be carefully considered, especially given the results of this study.

Treatment options for women diagnosed with LCIS include:

  • Close monitoring (includes regular clinical exams, regular screening mammography, and monthly breast self-exams)
  • Taking the breast cancer prevention drug tamoxifen, a hormonal agent, for a period of five years
  • Preventive (prophylactic) bilateral mastectomy, which can usually be followed by breast reconstruction

Though LCIS increases breast cancer risk, many women diagnosed with the condition never develop cancer. Thus, an appropriate treatment decision should take into account other factors, such as family history, in addition to an LCIS diagnosis.

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