Does breast cancer subtype influence the risk of recurrence in breast cancer patients?

This review evaluated the association between breast cancer subtypes and the risk of recurrence (return of the cancer) in breast cancer patients. 

Breast cancers (BC) can be classified based on the presence on their surface of some proteins called receptors which can influence how these cancers work. Most BC express on their surface female hormone receptors (estrogen or progesterone). This means that the growth of these cancers is fueled by these hormones. They are called estrogen receptor-positive (ER+) or progesterone receptor-positive (PR+) BC. Other types of BC have on their surface a protein called HER2 that helps the cancer grow (HER2+ BC). This type of BC tends to be more aggressive and fast-growing than other cancers. If a BC does not express any of these receptors it is called triple negative (TN) BC. The specific subtype of BC determines the best course of treatment for patients.    

This research examined the results of 15 studies and included 12,592 BC patients. Patients were treated with either radical mastectomy – RM (complete removal of the diseased breast) or breast conserving therapy – BCT (surgery to remove the cancer and radiation therapy). Some of the patients received additional therapies such as hormonal therapy, biological therapy, chemotherapy or radiotherapy. The particular subtype of BC for each patient was determined. The main parameter evaluated was the development of a BC recurrence.

After approximately 5 years of follow up, 7.9% (7.12% in the BCT group and 8.95% in the RM group) of patients experienced a recurrence. Patients with hormone receptor positive BC (ER+/PR+) had a lower risk of recurrence compared to TN BC patients following both BCT (by 62%) and RM (by 39%). ER+/PR+ BC patients were also less likely to develop a recurrence compared to patients with HER2+ BC following BCT (by 66%) and RM (by 31%).   

In summary, patients with ER+/PR+ BC had the lowest recurrence rate after both BCT and RM. Also, patients with HER2+ and TN BC were more likely to develop a recurrence after treatment. 

These findings suggest that BC subtypes should be determined for each patient when deciding treatment. Patients at increased risk of developing a recurrence should be considered for a more aggressive treatment.