Unlike ductal carcinoma in situ or DCIS, LCIS is not considered a precursor to invasive breast cancer so it does not require treatment. If left alone, LCIS does not turn into invasive breast cancer. Rather, LCIS is considered a marker for increased breast cancer risk in either breast, much like family history. Studies suggest that women who are found to have LCIS have an increased risk of breast cancer development of about 1%/year, so a 10% risk in 10 years, 20% risk in 20 years, etc.
LCIS is typically found incidentally on a biopsy that is done for calcifications or another abnormality found on breast imaging. It rarely causes symptoms.
Most often, LCIS is diagnosed by a needle biopsy. Patients who are diagnosed with LCIS are often referred to a surgeon for consideration of a surgical biopsy. The reason for this is because in some instances when a larger area of tissue is sampled, a patient can be found to have DCIS or a small invasive cancer co-existing with the LCIS, which would then require treatment. LCIS in and of itself does not need to be removed with surgery. The recommendation for surgical biopsy in this setting is evolving and should be discussed with a breast surgeon, as the ability to sample an area well with a needle biopsy is improving with larger amounts of tissue being removed and multiple samples being taken.
Although LCIS does not require treatment, the diagnosis increases a patient’s risk, so consideration of risk-reducing interventions and enhanced breast cancer screening should be discussed. Treatment with hormone blocking therapy has been shown to decrease the risk of breast cancer development in patients with LCIS by 56%. Evaluation by a physician at the UCLA High Risk Clinic would be appropriate to discuss risk-reducing medications. In addition, screening with either bilateral breast ultrasound or MRI in addition to mammography should be considered. Bilateral mastectomies for cancer risk reduction can also be considered although it is not typically recommended.
More recently, a newer form of LCIS has been identified, called pleomorphic LCIS. This is considered different from classic LCIS and appears to behave more like DCIS. For this reason, patients with pleomorphic LCIS should see a breast surgeon to discuss recommended treatment.