Stage 0 breast cancer, or ductal carcinoma in situ (DCIS), occurs when there are abnormal cells in the milk ducts, but these cells have not spread beyond the duct wall to reach surrounding tissue, the bloodstream, or the lymph nodes.

DCIS is noninvasive and is sometimes called "precancerous." However, DCIS has the potential to become invasive (non-invasive – a medical procedure that does not involve inserting devices into the body).

There are generally no symptoms of stage 0 breast cancer, although it can occasionally cause a lump in the breast or bleeding in the nipple.

The exact cause of stage 0 breast cancer is not clear, but the condition may be more common in people who:

- have a personal history of breast cancer
- have a family history of breast cancer or genetic mutations
- were born after the age of 30 or have never been pregnant
- had their period before the age of 12
- experienced menopause after the age of 55

Lifestyle factors can increase the chances of having this condition:

- physical inactivity
- large body size after menopause
- misuse of alcohol
- smoking

Due to the lack of symptoms, this stage can only be detected through routine check-ups with specialists.

For more information on Pink October, breast cancer awareness month, read the following articles:

Sources: Healthline, Women's Health