Lobular Carcinoma In Situ (LCIS) is a specific finding within breast tissue. It involves abnormal cell growth within the breast’s milk-producing glands, known as lobules. LCIS is a condition that signifies an increased risk for developing invasive breast cancer in the future, yet it is not considered breast cancer itself. This distinct classification guides how it is identified and managed.
Understanding LCIS
LCIS is characterized by abnormal cells within the lobules, the small, round sacs in the breast responsible for milk production. The term “in situ” indicates that these abnormal cells remain confined to their original location within the lobules and have not spread into the surrounding breast tissue. While its name includes “carcinoma,” LCIS is not classified as an invasive cancer, but rather as a marker for a higher likelihood of developing invasive breast cancer later.
The abnormal cells in LCIS are typically small and uniform, though variations like pleomorphic or florid LCIS involve larger, more atypical cells. This condition often occurs in premenopausal women. The presence of LCIS indicates a 7 to 12 times greater risk of developing invasive breast cancer in either breast compared to individuals without LCIS. Despite this increased risk, most women diagnosed with LCIS will not develop invasive breast cancer.
Diagnosis and Detection
LCIS usually does not produce any noticeable symptoms. Consequently, it is rarely detected through a physical breast exam or routine mammogram alone. Instead, LCIS is typically discovered incidentally during a breast biopsy performed for another reason.
A definitive diagnosis of LCIS requires a tissue biopsy, where a small sample of breast tissue is removed for microscopic examination. This procedure often involves a core needle biopsy, guided by imaging techniques like ultrasound or MRI. In some cases, a surgical excisional biopsy may be performed to confirm the diagnosis and ensure no other abnormalities are present.
Managing LCIS and Future Risk
Following an LCIS diagnosis, management strategies focus on careful monitoring and reducing the future risk of developing invasive breast cancer. Given that LCIS itself is not an invasive cancer, immediate aggressive treatment is not always necessary. Instead, close observation is a common approach, involving regular clinical breast exams and annual mammograms. Additional imaging, such as breast MRI, may also be recommended for more detailed monitoring.
Individuals with LCIS can explore options to help lower their breast cancer risk. Lifestyle adjustments, such as maintaining a healthy weight, engaging in regular exercise, and limiting alcohol intake, can contribute to risk reduction. For some, medication may be considered to reduce the likelihood of developing invasive breast cancer. Medications like tamoxifen, suitable for both premenopausal and postmenopausal women, or raloxifene and aromatase inhibitors, often for postmenopausal women, work by blocking or reducing estrogen’s effects, as many breast cancers are sensitive to this hormone. Tamoxifen has been shown to significantly reduce the risk of invasive breast cancer in individuals with LCIS.
While LCIS increases the risk of breast cancer, it does not guarantee its development. The decision to pursue risk-reducing medications or surgery, including options like prophylactic bilateral mastectomy, is a personal one made in consultation with healthcare providers. This discussion considers individual risk factors, preferences, and the potential benefits and considerations of each strategy.