Should all Women with Endocrine-Sensitive and Operable Breast Cancer Receive Adjuvant Hormonal Therapy?

Aggressive cancer?

There are many subtypes of breast cancers, with each having different survival rates. One way of predicting the nature of a tumour is by looking at its unique genetic makeup. In this study, researchers sought to determine if genetic characteristic analysis could accurately predict long-term survival rates of patients with confirmed early stage breast cancer.

Researchers recruited over 600 women with lymph node-negative breast cancer, a tumour size of 3 cm or smaller and who had undergone a complete or partial breast amputation with radiation followed by adjuvant tamoxifen (a type of hormonal therapy) or no adjuvant therapy at all. For each breast tumour, the expression of 70 genes was assessed and cancers were subsequently classified as ultra-low, low, or high-risk. Patients were followed up for 20 years after completing treatment.

Around 15% of women were found to have an ultra-low risk breast cancer. More importantly, women with such ultra-low risk breast cancer had a minimal risk of death after 20 years. On the other hand, their counterparts in the low- and high-risk groups were found to have a significantly increased risk of long-term mortality. All tumours designated as ultra-low risk were hormone receptor-positive.

“Women who have a tumour that is an ultralow-risk tumour by 70-gene signature can be reassured that their long-term outcome is expected to be excellent, with or without endocrine therapy. It is interesting to note that endocrine therapy hardly influenced mortality rates.”

Practice Changing

Current standard practice is to prescribe patients with hormone-sensitive breast tumours up to 5 years of hormonal therapy after surgically removing the cancer. While hormonal therapy is effective, some patients experience uncomfortable side effects such as nausea, fatigue and mood changes. This study successfully demonstrated the reliability of molecular gene-profiling to predict long-term mortality rates in breast cancer patients and fuels the debate of the necessity for prolonged endocrine therapy in all patients with hormone-receptor positive breast cancer.

An estimated 25% of postmenopausal women with breast cancer is thought to have ultra-low risk cancers. Of the 2 million cancers that will be diagnosed in the United States over a 10-year period, 500 000 may be indolent. Personalised molecular profiling provides patients with an ultra-low risk cancer to make a more informed decision whether or not to engage in long-term hormonal therapy and is, therefore, practice changing.