Noninvasive breast cancer, or carcinoma in situ, is defined as breast carcinoma limited to the ducts (ductal carcinoma in situ, or DCIS) or lobules (lobular carcinoma in situ, or LCIS) with no extension beyond the basement membrane into the surrounding tissue.
The two main types of noninvasive (in situ) cancer can be recognized from the histological pattern of the disease and cell type.
Ductal carcinoma in situ is the most common form of non-invasive carcinoma (making up 3 to 4 percent of symptomatic and 17 percent of screen detected cancers) and is characterized by ducts and ductules expanded by large irregular cells with large irregular nuclei.
In contrast, lobular carcinoma in situ is rare (0.5 percent of symptomatic and 1 percent of screen detected cancers) and shows as an expansion of the whole lobule by small regular cells with regular, round, or oval nuclei.
Lobular carcinoma was first described in 1919 as a "precancerous change." In 1941, it was named lobular carcinoma in situ (LCIS). Further definition of LCIS was provided by its division in 1950 into two types, noninfiltrating and infiltrating.
Since that time, some have suggested that lobular carcinoma is a misnomer, since many lesions, as suggested by the word carcinoma, may not progress or metastasize. A substitute definition would be lobular neoplasia.
There has been a lack of agreement among pathologists about whether small lesions should be considered as hyperplasia or in situ carcinoma. In general, lesions that involve only a few membrane bound spaces and that measure less than 2 to 3 mm in their greatest diameter should be regarded as hyperplastic lesions and not in situ carcinoma.
Other than genetic factors, the cause of this cancer is unknown.
LCIS is almost always a nonpalpable lesion. Mammography is of little value in the diagnosis of LCIS because the mammogram is positive in areas of benign disease.
LCIS is usually discovered only after biopsy for other clinically palpable lesions such as fibroadenoma, cysts, papilloma, papillomatosis, fat necrosis, and breast abscesses.
The diagnosis of LCIS is made on the basis of microscopic findings, usually as a result of the discovery of benign lesions.
About 15 to 20 percent of women with a diagnosis of LCIS will develop breast cancer in the same breast, and a further 1 to 15 percent will develop an invasive carcinoma in the contralateral breast.
There are three possible approaches to treatment: observation with yearly bilateral mammography; entering the patient into a trial of treatments to prevent breast cancer; or bilateral mastectomy.
The major issue in the management of LCIS is whether it is a premalignant lesion or a marker for increased risk for the development of breast carcinoma. It appears that most women with LCIS do not develop breast cancer, and the risk of breast cancer development is approximately equal in both breasts. Treatment strategies addressing one breast, such as unilateral mastectomy with contralateral biopsy, appear to be illogical because the risk of LCIS is bilateral regardless of the findings of the contralateral biopsy.
The current belief is that LCIS is only a marker of a population at increased risk for invasive breast cancer and is not a direct precursor for invasive cancer.
One treatment option for women with LCIS is careful observation - as would be carried out for any woman known to be at increased risk for the development of breast cancer due to a positive family history or prior history of breast cancer. In women unwilling to accept the 20 to 30 percent risk of the development of breast cancer associated with this option, bilateral simple mastectomy, usually with immediate breast reconstruction, is another therapeutic option.
Radiation therapy has no role in the management of LCIS. It is unnecessary to obtain histologically negative margins in women who will be followed expectantly, because LCIS is known to be a diffuse lesion. If observation is elected, it must last for the patient's lifetime, because the increased risk of breast cancer persists indefinitely. Most of the recent studies on LCIS nearly all agree that management of LCIS without proven invasive cancer should consist of careful follow-up.
Is this a precursor of breast cancer?
What are the chances that breast cancer will develop?
Where is the carcinoma located?
What are treatment options?
What are the pros and cons of a preventive mastectomy?
What surveillance and follow-up do you recommend?