Prognosis and survival for breast cancer

A prognosis is the doctor’s best estimate of how cancer will affect you and how it will respond to treatment. Survival is the percentage of people with a disease who are alive at some point in time after their diagnosis. Prognosis and survival depend on many factors.

The doctor will look at certain characteristics of the person and aspects of the cancer, such as its stage and grade and the size of the tumour. These are called prognostic factors. The doctor will also look at predictive factors, which influence how a cancer will respond to a certain treatment and how likely it is that the cancer will come back after treatment.

Prognostic and predictive factors are often discussed together. They both play a part in deciding on a prognosis and a treatment plan just for you. Only a doctor familiar with your medical history, the type, stage and other features of the cancer, the treatments chosen and the response to treatment can put all of this information together with survival statistics to arrive at a prognosis and the chances of survival.

Doctors use different prognostic and predictive factors for newly diagnosed and recurrent breast cancers.

The following are prognostic and predictive factors for breast cancer when it is first diagnosed.

The stage is the main prognostic factor for breast cancer. It describes how much cancer is in the body, where it is and how far it has spread.

Early-stage breast cancer is less likely to come back (recur), so it has a more favourable prognosis. Breast cancer that is diagnosed at a later stage has a greater risk of recurrence, so it has a less favourable prognosis.

When using the stage to estimate prognosis, doctors will consider if cancer has spread to lymph nodes and the size of the tumour.

Breast cancer that has spread to lymph nodes has a higher risk of coming back and a less favourable prognosis than breast cancer that has not spread to any lymph nodes.

The number of lymph nodes that contain cancer (called positive lymph nodes, or node-positive disease) is also important. The more positive lymph nodes there are, the higher the risk that breast cancer will come back.

Tumour size will affect prognosis no matter how many lymph nodes have cancer in them.

Breast tumours that are 5 cm or larger are more likely to come back after treatment than smaller tumours. If a breast tumour is smaller than 1 cm and the cancer hasn't spread to any lymph nodes, the prognosis is usually very favourable.

The grade is a description of how the cancer cells look compared to normal cells. Low grade means the cancer cells look a lot like normal cells. High grade means the cancer cells look more abnormal.

Low-grade tumours have a better prognosis because they grow slower and are less likely to spread than high-grade tumours.

Estrogen and progesterone can help some breast cancer cells grow. Some types of breast cancer cells have estrogen receptors (ERs) and progesterone receptors (PRs) on their surface or inside them. These receptors are where the hormones attach to the cells. Once they attach, the hormones can affect the behaviour or growth of the cells.

Breast cancer cells that have ERs and PRs need these hormones to grow and divide. Knowing the hormone receptor status of the tumour helps doctors predict how well hormone therapy will work and what other treatments may be effective.

Hormone receptor–positive tumours have ERs, PRs or both. They are usually less aggressive than hormone receptor–negative tumours (which don't have ERs or PRs). This means that they grow more slowly, are lower grade and have a lower risk of spreading. As a result, hormone receptor–positive tumours generally have a better prognosis in the short term than hormone receptor–negative tumours. However, hormone receptor–positive tumours sometimes recur years after treatment has finished.

Find out more about hormone receptor status testing.

The HER2 gene controls a protein on the surface of cells that promotes their growth. HER2-positive breast cancer means that the cancer cells make too many copies of, or overexpress, the HER2 gene.

HER2-positive breast cancer is more aggressive than HER2-negative breast cancer. This means that it is more likely to grow, spread and come back after treatment.

HER2-positive cancer has a better chance of responding to treatment that includes drugs that target the HER2 protein. But it still has a less favourable prognosis than HER2-negative breast cancer.

Find out more about HER2 status testing.

The risk for breast cancer increases with age. Breast cancer is most often found in people who are older than 55 years of age.

People younger than 35 years of age tend to be diagnosed with more aggressive, higher grade tumours. Their breast cancer is often more advanced at the time of diagnosis. This means that younger women have a greater risk that their breast cancer will recur and a poorer overall prognosis than post-menopausal women.

Doctors will consider the following prognostic factors for breast cancer that comes back after treatment.

The longer the period of time before breast cancer comes back, the better the prognosis. If breast cancer comes back more than 5 years after diagnosis, the outcome is usually better than when it recurs less than 2 years after diagnosis.

Cancer that comes back in the same breast is called a local recurrence. A local recurrence after lumpectomy and radiation therapy has a more favourable prognosis than cancer that comes back in other organs (called distant recurrence, or distant metastasis). If cancer comes back after being treated with a lumpectomy and radiation, doctors will often recommend a mastectomy to reduce the risk of the cancer recurring once again. But it's important to know that having a mastectomy does not always stop cancer from recurring. A local recurrence can also occur in scars from a lumpectomy or mastectomy.

A regional recurrence is when cancer has come back in nearby lymph nodes. When breast cancer comes back, it typically first goes to lymph nodes closest to the original tumour. So cancer may be in lymph nodes under the arm (called the axillary lymph nodes) or near the collarbone. A regional recurrence has a less favourable prognosis than a local recurrence and needs to be treated right away to stop cancer from spreading further.

Distant recurrence is when breast cancer has spread (metastasized) to other parts of the body. This can include the liver, lungs, brain and bones. Breast cancer that comes back in these areas has a far worse prognosis than a local or regional recurrence.

Distant recurrence will be treated like chronic disease. This means that your healthcare team will offer treatments to slow the cancer's spread and manage symptoms, rather than try to cure the cancer itself.