lobular carcinoma in situ

i was just diagnosed with lcis, and i heard sometimes people need treatment afterwards and some do not. what makes the difference?

[Cleveland Clinic]

Dear tgim, Lobular carcinoma in situ (LCIS) is an area (or areas) of abnormal cell growth that increases a person’s risk of developing invasive breast cancer later on in life. Lobular means that the abnormal cells start growing in the lobules, the milk-producing glands at the end of breast ducts. Carcinoma refers to any cancer that begins in the skin or other tissues that cover internal organs — such as breast tissue. In situ or “in its original place” means that the abnormal growth remains inside the lobule and does not spread to surrounding tissues. People diagnosed with LCIS tend to have more than one lobule affected.  

Treatment of LCIS is focused on risk reduction for development of cancer and usually falls into one of 3 categories; careful observation, medications to decrease estrogen, or some women might opt for surgery to remove the breasts (prophylactic mastectomy).  Decisions are made after discussion and weighing of risks and benefits for the individual patient.  Factors such as estrogen receptor status, age, and menopausal status, risk factors (strong family history, BRCA1 or BRCA2 gene mutations) are taken into account in this risk/benefit discussion.

[tgim]

is lcis considered cancer or pre-cancer? thank you