Comparing endocrine treatment versus chemotherapy for metastatic breast cancer

This study compared hormone therapy and chemotherapy for the treatment of metastatic (cancer that has spread) breast cancer. The authors concluded that hormone therapy plus targeted therapy is better than chemotherapy for patients with metastatic breast cancer.

Different types of breast cancer have different receptors. Receptors are proteins found on the surface of the cancer cells. The most common type of metastatic breast cancer has a receptor called HR and is missing another receptor called HER2. Treatment for this type of breast cancer remains challenging. 

Hormone therapy plus targeted therapy is usually recommended as a first-line treatment. However, chemotherapy is also commonly used. Few studies have compared these two treatment approaches. Whether hormone therapy plus targeted therapy is more effective for metastatic breast cancer with HR but not HER2 is unclear.

This study analyzed the results of 140 studies. These studies had a total of 50,029 patients. The most common treatments were anastrozole (Arimidex) and PL (palbociclib, letrozole). Anastrozole (Arimidex) and letrozole (Femara) are hormone treatments and palbociclib (Ibrance) is a targeted therapy.  Patients were followed-up for an average of 20 months.

Compared to anastrozole alone, 23 treatments significantly increased the amount of time before the cancer got worse (disease progression). The PL regimen significantly reduced the risk of disease progression by 58%. The PF (palbociclib, fulvestran) regimen lowered this risk by 63%. Some chemotherapy regimens also lowered the risk of disease progression by 53 – 61% compared to anastrozole alone.

27 treatments showed a significantly better response (tumor disappearance or shrinkage) compared to anastrozole. The PL regimen was associated with a 1.85-fold higher chance of responding to treatment compared to anastrozole alone. Some chemotherapy regimens also improved treatment response by 15.0-fold or more compared to anastrozole alone.

This study concluded that hormone therapy plus targeted therapy is an effective treatment for patients with metastatic breast cancer. The authors suggest that this combination leads to better survival compared to chemotherapy alone.

This study reviewed the results of many other studies. Each study had different treatments and patient populations. More studies that directly compare hormone therapy and chemotherapy are needed to confirm these results.

Talk to your doctor about your treatment options.