Lobular carcinoma in situ (LCIS) is a non-invasive lesion , where abnormal cells develop in the milk glands, known as lobules. .

• In Denmark, LCIS is considered a precursor for developing invasive lobular carcinoma later on.[4]
• There are no clinical features – only 40% of the cases are associated with microcalcifications. In most cases it is an incidental finding in a biopsy for some other mass producing lesion such as a fibroadenoma.
• In Denmark, more than 90% are diagnosed in premenopausal women, and the mean age are 45 years.
• Studies shown that it is often multicentric (70%) and frequently bilateral (22%-60%) [5]

To distinguish whether possible predictive factors exists for developing invasive lobular carcinoma, the registration of the following is of uttermost importance

• Genetic predisposition
• Nulliparity
• Age at first-time birth
• Age at menarche
• Previously biopsies with/without ALH/LCIS
• Menopause
• Hormone replacement therapy
• HRT.

Recommended treatment in Denmark according to Danish Breast Cancer Group (DBCG) if the excisional biopsy shows lobular carcinoma

• Clinical control scans every second year
• Mammography
• Participation in clinical trials with anti-estrogen treatment
• Bilateral mastectomy under certain circumstances – (eg. patients wish or patients with other predictive factors)

Recommended treatment in Denmark according to Danish Breast Cancer Group (DBCG) if the core needle biopsy shows lobular carcinoma

• If the mammography and ultrasound is normal (eg. without any suspicious abnormality), treatment is as according to treatment mentioned above.
• If the mammography and ultrasound is positive (eg. with any suspicious abnormality) an excisional biopsy will determine any further treatment.