Benefits of post-operative chemotherapy according to hormone receptor status

This study compared the benefits of chemotherapy according to hormone receptor status. The main findings were:

1. In cancers without hormone receptors, the benefits of adding chemotherapy were significant;
2. In cancers with hormone receptors, chemotherapy only offered modest improvement.

Some types of cancer cells have what are called “estrogen receptors” (ER) on their surface. These structures recognize estrogen (the female sex hormone) and send a signal to promote cell division and tumor growth. Therapies such as Tamoxifen block these receptors, slowing down the progression of cancer. ER positive tumors generally have a better prognosis. Unfortunately, not all tumors are ER positive to allow Tamoxifen treatment. For ER negative tumors, chemotherapy is usually the best option. Chemotherapy and/or hormone therapy are given in addition to surgery and radiation treatment.

This study compared the benefits of chemotherapy in ER negative versus ER positive cancers (treated with Tamoxifen). The analysis was performed using patient data from 3 consecutive trials performed from 1985 to 1999. A total of 6644 patients with cancer spread to the lymph nodes were included. The use of chemotherapy led to a 22.8% improvement of disease-free survival (survival without cancer recurrence) for ER negative cancers. This improvement was less dramatic for ER positive cancers treated with Tamoxifen (7%). Chemotherapy improved overall survival by 16.7% in ER negative versus 4% in ER positive cancer.

These results suggest that chemotherapy has significant benefits for patients with ER negative tumors. Such patients traditionally had worse prognoses, since Tamoxifen treatment did not work in their case. Patients with ER positive tumors might also benefit from chemotherapy, although improvements were modest.

Potential limitations of this study: data came from 3 separate trials performed before newer therapies became available.