Stage zero breast cancer is the earliest stage of breast cancer. The condition has not spread beyond where it started to other parts of the breast. Doctors can treat stage zero breast cancer early when it has a good prognosis.
Doctors use staging to identify how far cancer has spread. Staging cancer also provides information about how quickly it is growing and its severity.
Stage zero (stage 0) breast cancer is also known as carcinoma in situ. According to the American Cancer Society, people with a type of breast cancer that has not spread beyond the breast tissue have a 5 year survival rate of 99%.
This survival rate means that 99% of women with stage 0 breast cancer live at least 5 years after diagnosis.
In this article, we look at the types of stage 0 breast cancer and how to treat the disease.
The stage of breast cancer provides information about how invasive and aggressive it is. It also shows whether cancer has spread or is likely to spread to other areas of the body.
Stage 0 breast cancer is noninvasive, meaning it has not spread beyond where it started to other parts of the breast or other organs.
Stage 0 breast cancer does not usually cause other symptoms. In some cases, a doctor discovers stage 0 breast cancer by accident, such as after a biopsy or while carrying out an imaging test on a different lump. Doctors may diagnose some people after feeling a lump or after routine screening.
The term ‘metastasis’ means cancer has spread to other organs. Although breast cancer has not spread at stage 0, a person may require treatment to prevent future metastasis.
Finding the right treatment, or whether treatment is necessary, depends on what type of stage 0 breast cancer a person has, and other factors such as age and family history.
There are two types of stage 0 breast cancer.
Lobular carcinoma in situ
Lobular carcinoma is cancer of the glands that produce breast milk. These glands are called the lobes, or lobules.
Lobular carcinoma in situ (LCIS) is a stage of lobular cancer that does not usually spread. However, it does increase a person’s risk of developing other types of breast cancer. Most women get lobular carcinoma before menopause when they are between 40–50 years of age.
Fewer than 1 in 10 women get this type of cancer after menopause.
For this reason, a diagnosis of LCIS may mean that a woman will need more frequent breast cancer screenings in the future.
Ductal carcinoma in situ
Ductal carcinoma in situ (DCIS) is breast cancer of the milk ducts. The milk ducts are canals that take milk from the milk glands to the nipple.
Without treatment, DCIS can spread and become more aggressive. In about half of all cases, DCIS may become invasive cancer.
A doctor may recommend an MRI scans or a mammogram and a biopsy to diagnose breast cancer and determine its stage.
They will stage a cancer from 0 to 4. A higher stage indicates more advanced disease.
To determine the stage of breast cancer, doctors look at three factors:
- T, or the size of the breast tumor.
- N, or the spread of the cancer to lymph nodes, and how many it has affected.
- M, or the cancer has spread to other areas of the body, which is known as metastasis.
There are four stages of breast cancer after stage 0:
- Stage 1: The tumors are small and have spread very little, if at all.
- Stage 2: At this stage, the tumors are slightly larger and have spread to nearby tissue but not other organs. They may infect a small number of lymph nodes or a limited section of nearby tissue.
- Stage 3: These cancers are larger and have spread further than stage 2 tumors. They may infect wider areas of breast tissue or several nearby lymph nodes but not other organs.
- Stage 4: The cancer cells have spread to other organs in the body.
Doctors may divide each stage into A and B categories.
Cancers that they classify as B are more advanced than A. For example, stage 1B breast cancer will have spread further or become larger than stage 1A breast cancer.
Will it spread?
LCIS will not typically spread to other areas. However, it requires careful and regular monitoring, as it is a risk factor for other breast cancers.
Doctors cannot predict which presentations of DCIS will become more aggressive and spread. However, low grade tumors, or those with well-defined borders and slow growth, may be less likely to become invasive and spread.
In recent years, treatment of this noninvasive form of breast cancer has been the source of some controversy.
Because DCIS does not cause symptoms nor spread in every case, some women may experience the side effects of treatment they feel was unnecessary or harmful.
A 2015 study added to criticism of DCIS treatment when it found no difference in survival rates between women who received treatment and those who did not. However, doctors who support early treatment counter this argument by pointing to data showing there is no way to predict whether or not DCIS will become invasive.
Any treatment needs to take into account the person’s history, the needs and goals of treatment, and any other breast cancer risk factors that may be present, such as having a parent or grandparent with breast cancer.
Treatment options include:
- Breast surgery: A surgeon may remove one or both breasts in a procedure called a mastectomy, or remove part of the breast with a lumpectomy.
- Radiation therapy: The breast and sometimes lymph nodes receive treatment with radiation, which targets and kills cancer cells.
- Hormonal therapy: Doctors recommend hormonal therapy for people with hormone receptor-positive breast cancer. A person takes hormonal drugs that treat cancer and may also prevent it from returning.
A doctor may also recommend more regular screening for women with a history of stage 0 breast cancer.
A diagnosis of stage 0 breast cancer may cause anxiety, but the 5 year survival rate is extremely high. Treatment can save lives, particularly when there is a risk of cancer returning or spreading. Some people may not even need treatment.
Women who are unsure as to whether treatment will be necessary for their presentation of breast cancer should talk to a doctor they trust. If they are still uncertain, they can consider seeking a second opinion.
How do I know if I need treatment for stage 0 breast cancer?