The exact cause of mixed ductal and lobular carcinoma in situ (DCIS/LCIS) of the breast is unknown. Risk factors for the development of DCIS/LCIS include older age, a family history of breast cancer, and certain genetic factors, such as mutations in the BRCA1 and BRCA2 genes.
Diagnosis of DCIS/LCIS is made by a breast examination, imaging studies, such as mammography and ultrasound, and a biopsy of the suspicious area. The biopsy is examined under a microscope to look for cells that have the features of DCIS/LCIS.
The differential diagnosis of DCIS/LCIS includes other conditions that cause similar symptoms, such as benign breast conditions, such as fibroadenomas, and other forms of breast cancer, such as invasive ductal carcinoma.
Treatment of DCIS/LCIS is usually surgical removal of the affected area. This may be done by either a lumpectomy or a mastectomy. Radiation therapy may also be recommended, depending on the size and type of DCIS/LCIS.
The prognosis for DCIS/LCIS is generally good, with a cure rate of over 90%. The risk of recurrence is low, and the risk of progression to invasive cancer is also low.