A diagnosis of lobular carcinoma in situ (LCIS) or ductal carcinoma in situ (DCIS) is not as scary as it sounds. The Latin term “in situ” means in place. LCIS and DCIS can not spread outside the breast unless they undergo a transformation to become invasive cancer. That capacity for spreading, or metastasizing, is what makes invasive breast cancer dangerous.
The two types of carcinoma in situ are similar in that there are abnormal cells growing within the breast, but the similarities end there. LCIS develops in structures in the breast called lobules, which are the milk-producing glands, while DCIS develops in the ducts that carry milk from these glands.
LCIS serves as a warning sign that a woman is at risk for developing breast cancer, while DCIS is considered a very early stage of breast cancer. DCIS might more accurately be called a precancer, though, because it has no capacity to metastasize as invasive cancer does unless it first undergoes a change. It is thought that DCIS, if left untreated, would not become invasive in approximately half of the women who have it. There is no way to tell which will not progress, so its presence is taken seriously and it is treated as early cancer.
Depending on how extensive the DCIS is and what its characteristics are, it may be treated surgically with a lumpectomy or a mastectomy, and may require radiation. The risk of recurrence is very low.
The usual treatment for LCIS is not really treatment, but careful surveillance. Women get regular breast exams and a yearly mammogram. Thirty or forty years ago, LCIS was considered cancer and women would have a mastectomy after it was diagnosed. It was later determined that LCIS was simply a warning sign that breast cancer could develop in either breast. Both breasts have to be removed if risk is to be reduced, but prophylactic mastectomy for LCIS is considered “an overly aggressive approach” according to the National Cancer Institute.
Ideas about carcinoma in situ have changed over the years and are still changing. There is some uncertainty about the implications of having it for any particular woman. No one likes to be told they are high risk for breast cancer or that they have an early stage of the disease, but it is important to understand that there is a distinction between carcinoma in situ and invasive cancer so as not to take more drastic measures than are necessary.
Having a bilateral prophylactic mastectomy for either LCIS or DCIS is more than is needed unless there are additional risk factors like having a faulty BRCA gene or a very strong family history of breast cancer.
So why are women diagnosed with LCIS or DCIS told that prophylactic mastectomy is an option? Doctors are obligated to describe all options for treating a disease. With carcinoma in situ, it is important to understand that the most drastic treatment is not necessarily the best.