Stage 0 (carcinoma in situ) breast cancer
Stage 0, also called carcinoma in situ, is the earliest stage of breast cancer. This very early breast cancer stage is sometimes interpreted as a precancerous condition. Many stage 0 breast cancers do not require treatment. When they do, the approach is generally very successful.
The five-year survival rate for stage 0 breast cancer is 93 percent. This means that almost all women diagnosed with stage 0 disease will live for at least five years after being diagnosed. In fact, women diagnosed with stage 0 breast cancer usually live long and healthy lives.
What is stage 0 breast cancer?
At stage 0, the breast mass is noninvasive. At this stage, there is no indication that the tumor cells have spread to other parts of the breast or other parts of the body. Often, stage 0 is considered a precancerous condition that requires close observation, but not treatment.
Stage 0 breast cancer is difficult to detect. There may not be a lump that can be felt during a self-examination, and there may be no other symptoms. However, breast self-exams and routine screening are always important and can often lead to early diagnosis, when the cancer is most treatable. Stage 0 disease is most often found by accident during a breast biopsy for another reason, such as to investigate an unrelated breast lump.
Types of stage 0 breast cancer
There are two types of stage 0 breast cancer:
- Ductal carcinoma in situ (DCIS) occurs when breast cancer cells develop in the breast ducts. Today, stage 0 DCIS is being diagnosed more often because more women are having routine mammogram screenings. DCIS can become invasive, so early treatment can be important.
- Lobular carcinoma in situ (LCIS) occurs when abnormal cells develop in the lobules. These cells are not cancerous and this condition rarely becomes invasive cancer. However, women who develop LCIS may be at increased risk for developing breast cancer in the future. For women who develop LCIS, the risk of getting an invasive cancer is 20 - 25 percent over 15 years after the initial diagnosis.