Women with breast cancer may have questions about their prognosis and survival. Prognosis and survival depend on many factors. Only a doctor familiar with a person’s medical history, type of cancer, stage, characteristics of the cancer, treatments chosen and response to treatment can put all of this information together with survival statistics to arrive at a prognosis.
A prognosis is the doctor’s best estimate of how cancer will affect a person, and how it will respond to treatment. A prognostic factor is an aspect of the cancer or a characteristic of the person that the doctor will consider when making a prognosis. A predictive factor influences how a cancer will respond to a certain treatment. Prognostic and predictive factors are often discussed together and they both play a part in deciding on a treatment plan and a prognosis.
The following are prognostic and predictive factors for breast cancer.
The stage of breast cancer is an important prognostic factor. Lower stages have less risk of the cancer coming back (recurring) and a more favourable prognosis. Higher stages have a greater risk of recurrence and a less favourable prognosis.
The most important stage-related factors are lymph node involvement and tumour size.
Lymph node status
The most important prognostic factor for breast cancer is whether or not the axillary lymph nodes contain cancer.
- Breast cancer that has spread to the lymph nodes (positive lymph nodes) has a higher risk of recurring and a less favourable prognosis than breast cancer that has not spread to the lymph nodes (negative lymph nodes).
- Breast cancer may also spread to the internal mammary lymph nodes, without having spread to the axillary lymph nodes. In this situation, the risk of recurrence is high, even though the axillary lymph nodes are negative.
The number of positive lymph nodes is also an important prognostic factor.
- The greater the number of positive lymph nodes, the higher the risk of recurrence.
- The highest risk of recurrence is for breast tumours with 4 or more positive lymph nodes.
The size of a breast tumour is the second most important prognostic factor for breast cancer. The tumour size is an independent prognostic factor, regardless of the lymph node status.
- The size of the tumour increases the risk of recurrence. Large breast tumours (5 cm or greater) have the greatest risk of recurrence.
- Breast tumours smaller than 1 cm with no positive lymph nodes have the most favourable prognosis.
The grade of the breast cancer also affects prognosis.
- Low-grade tumours often grow slower and are less likely to spread than high-grade tumours.
Type of tumour
The type of breast cancer tumour can affect the prognosis.
- For invasive ductal carcinoma, the tubular, mucinous, medullary and papillary types have a more favourable prognosis and a better overall survival than invasive ductal carcinoma, not otherwise specified (NOS).
- Inflammatory breast cancer has a less favourable prognosis.
Lymphatic and vascular invasion
Cancer cells that have spread from the breast tumour into the lymph vessels or blood vessels in the breast tissue around the tumour have a greater risk of recurrence and a less favourable outcome.
Hormone receptor status
Hormone receptor status is a predictor of whether or not a tumour will respond to hormonal therapy.
- Breast tumours that are hormone receptor positive (HR+) are more likely to respond to hormonal therapy.
- Estrogen receptor–positive (ER+) and progesterone receptor–positive (PR+) tumours are often less aggressive, low-grade tumours that are less likely to spread than tumours that are hormone receptor negative (HR–).
HER2 status is another prognostic factor and may also be used to predict response to certain therapies.
- Tumours that overexpress HER2 (HER2-positive tumours) tend to be higher grade tumours that are more likely to spread than tumours that do not overexpress HER2.
- Women with HER2-positive tumours may not respond well to hormonal therapies like tamoxifen (Novadex, Tamofen) and are likely to respond well to a drug called trastuzumab (Herceptin).
A woman’s age at the time of her breast cancer diagnosis can affect the prognosis.
- Younger women (under 35 years of age) usually have a greater risk of recurrence and a poorer overall prognosis than older, post-menopausal women.
- Younger women with breast cancer tend to have more aggressive, higher-grade cancer and more advanced breast cancer at the time of diagnosis.
Tumour recurrence or metastasis after primary treatment
There are some factors that may affect prognosis of recurrent breast cancer.
- length of time from treatment to recurrence
- Women whose cancer comes back more than 5 years after their diagnosis have a better outcome than those who have a recurrence less than 2 years after diagnosis.
- The longer period of time a woman is disease-free, the better the outcome.
- type of recurrence
- A recurrence in the breast (local recurrence) after a lumpectomy and radiation therapy has a more favourable prognosis than cancer that recurs in other organs (distant recurrence or metastases).
- A recurrence in the chest wall sometimes indicates a higher chance of distant metastases, although sometimes a single recurrence occurs without distant disease.
- type of metastasis
- Liver, lung or brain metastases have a poorer outcome than local metastases in the breast, chest wall or armpit (axilla).
- Bone metastases have an intermediate prognosis, in between that of liver, lung and brain metastases and local or chest wall metastases.