Literally meaning in place, the term in situ refers to a very early form of cancer. In general, the term in situ Lobular Carcinoma in Situ (LCIS)/Lobular Neoplasia | Breast Cancer Symptoms and Diagnosis | Imaginis - The Women's Health & Wellness Resource Network

The Women's Health Resource. On the web since 1997.

Lobular Carcinoma in Situ (LCIS)/Lobular Neoplasia

Literally meaning "in place," the term "in situ" refers to a very early form of cancer.  In general, the term "in situ" is used to indicate that abnormal cancer cells are present but have not spread past the boundaries of tissues where they initially developed.   Lobular carcinoma in situ (LCIS) refers to a sharp increase in the number, appearance, and abnormal behavior of cells contained in the milk-producing lobules of the breast (found within the lobes).

Though categorized as a stage 0 breast cancer (the earliest stage), LCIS is not considered a cancer. Rather, it is marker (a signal) that breast cancer may develop. In fact, LCIS has recently been renamed lobular neoplasia to signify this belief.  Neoplasia is defined as an abnormal growth in the number of cells. Though LCIS is not considered a cancer, women who are diagnosed with LCIS (also called lobular neoplasia) 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 (either lobular, or more commonly, infiltrating ductal carcinoma) within her lifetime.

The number of women diagnosed with LCIS has increased in recent years, most likely due to more rigorous breast cancer screening and advances in mammography techniques.  Often, LCIS is encountered serendipitously (by chance) while a pathologist is examining tissue from a breast biopsy that was performed for another reason (for example, to examine an area of concern found by physical examination or with mammography).

Treating LCIS

Treatment Options for Women With LCIS

  1.       Close monitoring (includes regular clinical exams, regular screening
  mammography, and monthly breast self-exams)

  2.       Taking tamoxifen, a hormonal agent, for a period of five years

  3.       Enrolling in the STAR clinical trial, which is comparing two drugs,
  tamoxifen and raloxifene (must meet eligibility requirements)

  4.       Preventive (prophylactic) bilateral mastectomy, usually followed by
  breast reconstruction

Currently, the majority of women who have been diagnosed with LCIS do not receive treatment after biopsy.  Instead, they are closely monitored by physicians with frequent clinical breast exams and mammograms.  It is essential that women with LCIS examine their breasts carefully, once a month, and see a physician immediately if they notice any changes or abnormalities

Prophylactic Mastectomy

Some women with LCIS who are very concerned with developing breast cancer (such as those who also have a strong family history of breast cancer and/or a proven genetic mutation) opt for the preventive removal of both breasts, a procedure called a prophylactic mastectomy. Research shows that prophylactic mastectomy markedly reduces a woman's risk of developing breast cancer for those at high risk.  Prophylactic mastectomy may be followed by immediate or delayed breast reconstruction.While a bilateral prophylactic mastectomy removes the majority of breast tissue and reduces the risk of developing breast cancer, it is impossible to remove every breast cell. Thus, it is still possible to develop breast cancer even if both breasts are removed. According to Lynn C. Hartman, MD of the Mayo Clinic in Rochester, Minnesota, if only three cells are left after a mastectomy, cancer could develop from those three cells.  In a study conducted by the Mayo Clinic, three of 214 women who had prophylactic bilateral mastectomies between 1960 to 1993 developed breast cancer and two of the women later died. 


The option of taking medication to reduce breast cancer risk is also available to women with LCIS.  In a large clinical trial conducted by researchers with the National Surgical Adjuvant Breast and Bowel Project (NSABP), 13,388 women who were at high risk of developing breast cancer were given either the drug tamoxifen or a placebo (sugar pill) to determine whether tamoxifen could lower the risk of breast cancer.  All of the women in the study had a history of LCIS and/or other risk factors for breast cancer (such as a family history or atypical hyperplasia, an abnormal increase in the number of breast cells, diagnosed by a previous breast biopsy).  The trial revealed a 49% decrease in the incidence of invasive breast cancer in women who were given tamoxifen in the study compared with women who took the placebo (sugar pill).  As a result of the NSABP trial, the U.S. Food and Drug Administration (FDA) approved the use of tamoxifen for women at high risk of breast cancer.  Many women with LCIS take tamoxifen to help prevent breast cancer.  Women with LCIS are encouraged to discuss the possibility of taking tamoxifen with their physicians.

Additional Resources and References

Updated: December 2010