Risk of recurrence after surgery and additional treatments

After surgery for breast cancer your doctor will look at the risk that the cancer will come back (recur) to decide if you should be offered additional treatments (called adjuvant therapy). The higher the risk that the cancer will recur, the more likely giving an adjuvant therapy will help prevent it.

The risk of recurrence is based on the cancer’s prognostic factors, including:

• the size of the tumour
• the grade of the tumour
• the hormone receptor status of the cancer cells
• the HER2 status of the cancer cells
• if the cancer has spread to the lymph nodes
• if the cancer has grown into lymph vessels, blood vessels or both

These prognostic factors are grouped into 3 levels. Your healthcare team uses the level of risk of recurrence to predict how likely it is that the breast cancer will come back and help them decide if they should offer you adjuvant therapy.

Breast cancer has a low risk of recurrence when all of the following apply:

• The tumour is smaller than 1 cm in diameter.
• The cancer cells have receptors for both estrogen and progesterone (they are hormone-receptor positive).
• The cancer is grade 1 (low grade).
• The cancer has not spread to lymph vessels or blood vessels in the breast tissue.

Breast cancer has a moderate, or intermediate, risk of recurrence when all of the following apply:

• The tumour is up to 5 cm in diameter.
• The cancer cells are hormone receptor positive.
• The cancer is grade 1 (low grade) or grade 2 (intermediate grade).
• The cancer has spread to only 1–3 lymph nodes.
• The cancer has not spread to lymph vessels or blood vessels in the breast tissue.

Breast cancer has a high risk of recurrence when any of the following apply:

• The tumour is larger than 5 cm in diameter.
• The cancer cells are triple negative, which means they don’t have receptors for estrogen or progesterone and they don’t have extra copies of the HER2 gene.
• The tumour is high grade (grade 3).
• The cancer has spread to lymph vessels or blood vessels in the breast tissue.
• The cancer has spread to 4 or more lymph nodes.
• The cancer has spread to muscles on the chest or the skin of the breast.
• The cancer is inflammatory breast cancer.
• The cancer cells are HER2 positive.

Your healthcare team may offer one or more of the following treatments as adjuvant therapy.

All women who had a partial mastectomy (also known as lumpectomy) will be given radiation therapy. Some women may need more radiation therapy if there are cancer cells at or close to the surgical margins or in lymph nodes.

Hormonal therapy is almost always offered for hormone receptor–positive breast cancer.

Chemotherapy is always offered to women who have breast cancer with a high risk of recurrence because it significantly reduces risk. Women with a low risk of breast cancer recurrence are not usually offered chemotherapy because it does not significantly reduce risk.

If you have breast cancer with a moderate risk of recurrence, you may be offered chemotherapy after the healthcare team has discussed the risks and side effects of chemotherapy with you.

Your healthcare team may offer to do the Oncotype DX test to get a better idea of how likely the cancer is to recur. This test looks at 21 different genes in breast cancer cells. If some genes are turned on, or expressed, it may mean that the cancer is a more aggressive cancer and more likely to come back after treatment.

Your healthcare team may also offer to do the Oncotype DX if you have invasive breast cancer that has receptors for estrogen, progesterone or both (it is ER+, PR+ or both) and HER2 negative to see if adding chemotherapy to hormonal therapy may lower your risk of recurrence.

The results of the Oncotype DX test are given as a number between 0 and 100. The lower the number, the lower the risk that the cancer will come back or spread.

Chemotherapy is not offered to women with a low score because they are not likely to benefit from chemotherapy. Chemotherapy is offered along with hormonal therapy to women with a high score because there is a greater risk that the cancer will come back or spread.

Talk to your healthcare team about adjuvant therapy and if the Oncotype DX test would be helpful for you. This test is available in Canada, but it is not funded by the provincial or territorial healthcare plans in all cases.

Targeted therapy is usually offered for HER2-positive breast cancer. It is always given with chemotherapy. It is then continued by itself, usually for a total of 1 year.