LCIS Associated with Increased Risk of Invasive Breast Cancer

Reviewed study: "LCIS Associated with Increased Risk of Invasive Breast Cancer" by P. Chuba et al., Journal of Clinical Oncology, August 20, 2005

Is this for me? You might want to read this article if you've been diagnosed with lobular carcinoma in situ (LCIS).

Background and importance of the study:Lobular carcinoma in situ, or LCIS, is generally considered to be a pre-cancerous condition. It is lobular because the cancer-like cells start in and stay inside the lobules—the glands that make milk. Carcinoma refers to any cancer that begins in the tissues that cover the inside linings of your body, such as within breast tissue, or the outside coverings (your skin). In situ ("in its original place") means that the cancer cells have not spread into any surrounding tissues.

Studies have shown that LCIS increases a woman's risk of developing invasive breast cancer. But it's less clear how MUCH this risk increases. Knowing your level of risk helps you decide what protective steps to take. These steps can range from having your doctor monitor you closely for breast cancer, to taking tamoxifen, to having preventive surgery.

The study reviewed here looked at findings from many women to determine how much LCIS increases the risk of later developing invasive breast cancer.

Study design: Researchers from Michigan and California used a national database of cancer information called the Surveillance, Epidemiology, and End Results (SEER) registry. This registry is a huge collection of carefully organized information on how many people in the United States get cancer each year (incidence) and how long they live (survival). The National Cancer Institute manages this registry.

To see how much LCIS increases the risk of invasive breast cancer, the researchers compared two groups of women in the SEER registry. First they identified all the women who were diagnosed with LCIS between 1973 and 1998. Then they determined how many of these women were diagnosed with invasive breast cancer a year or more after their LCIS diagnosis. They also identified all the women in the SEER registry who were diagnosed with invasive breast cancer between 1973 and 1998 who had NOT had a prior diagnosis of LCIS. This is called primary invasive breast cancer.

In comparing the two groups of women with invasive breast cancer, the researchers looked at:

• where the breast cancer was located within the breast
• which breast the cancer was located in (right or left)
• the stage of the breast cancer
• the women's race

For the women who had first had LCIS, the researchers also looked at:

• age when diagnosed with LCIS
• year of LCIS diagnosis
• type of surgery for LCIS
• number of years between LCIS diagnosis and invasive breast cancer diagnosis

Results: The researchers found that between 1973 and 1998:

• 4,853 women were diagnosed with LCIS. Of these women, 350 were diagnosed with invasive breast cancer a year or more later.
• 255,114 women were diagnosed with primary invasive breast cancer.

This means that women who had been diagnosed with LCIS were 2.4 times more likely than other women to develop invasive breast cancer. In addition: The cancers found in women who first had LCIS were at earlier stages than the cancers in the women with a primary invasive cancer diagnosis. And more women with LCIS had cancers that were node negative.

For some factors, there was no difference between women diagnosed first with LCIS and the other women who developed invasive breast cancer:

• The location of the invasive cancer within the breast was about the same in both groups.
• There were about the same number of invasive cancers in the right breast and the left breast in both groups.

Overall, 7.1% of the women diagnosed with LCIS were diagnosed with invasive breast cancer within 10 years. The risk of getting invasive breast cancer increased with age:

The race of the women did not play a role in whether they developed invasive breast cancer after LCIS. Also, about the same number of invasive breast cancers were found in the right and left breasts. This means that the side the LCIS was on didn't seem to affect which side the invasive breast cancer was on.

The researchers wondered if the risk of invasive breast cancer was related to the year of LCIS diagnosis. (They wanted to see if diagnostic advances had played a role.) To do this, they compared women diagnosed with LCIS between 1973 and 1985 (1,293 women) to those diagnosed with LCIS between 1986 and 1998 (3,560 women):

This difference continued 10 and 15 years after LCIS diagnosis.

A majority of the women with LCIS (68%) had lumpectomy or breast-saving surgery; 28% had mastectomy; and 4% had some type of biopsy.

Ten years after LCIS diagnosis:

• 8.8% of the women who had breast-saving surgery for LCIS later developed invasive breast cancer. Regardless of which breast the LCIS had been in, invasive breast cancer developed about as often in the left breast as in the right.
• 5.7% of the women who had mastectomy for LCIS later developed invasive breast cancer. Since the breast was removed for LCIS, nearly all of the new invasive cancers happened in the other breast.

This small difference in the risk of invasive cancer also was noted at 15, 20, and 25 years after LCIS diagnosis.

Conclusions: The researchers concluded that LCIS is associated with an increased risk of invasive breast cancer. No matter which breast the LCIS is in, the increased risk for invasive cancer is the same for both breasts. Based on the findings of this study, 10 years after an LCIS diagnosis, about 7% of women will be diagnosed with invasive breast cancer.

• Research News on Diagnosis (27 Articles)
• Back to top