Does radiation therapy improve survival in early stage breast cancer patients treated with lumpectomy and tamoxifen?

This study evaluated whether there is any benefit from radiation therapy (RT) in women over the age of 70 with early stage breast cancer treated with lumpectomy (surgical removal of the cancerous lump) and tamoxifen.

Breast cancer in older patients is often fueled by estrogen, a female sex hormone. These cancer cells respond to estrogen via its receptor (a protein found on the surface of the cells). This type of cancer is called estrogen receptor-positive (ER+) breast cancer. In early stage breast cancer, the cancer is usually just a lump, confined to the breast. In this stage, treatment often starts with breast conserving surgery which only involves removal of the lump (lumpectomy). Hormone therapy is given to ER+ breast cancer patients to prevent the cancer from coming back. Tamoxifen (Nolvadex) is a type of hormone therapy that works by blocking estrogen receptors on breast cancer cells. RT after breast conserving surgery has been shown to decrease the risk of the cancer coming back in the other breast. This study aimed to test if there is any benefit to additional RT in older ER+ breast cancer patients treated with lumpectomy and tamoxifen.

636 women aged 70 or more with early stage ER+ breast cancer took part in this study. After lumpectomy, patients were assigned to receive either tamoxifen and RT (TamRT group) or tamoxifen alone (Tam group). The main parameters evaluated were the development of a recurrence (return of the cancer), disease-specific survival or DSS (defined as the percentage of people who have not died because of breast cancer after a certain period from treatment) and overall survival or OS (defined as the percentage of patients who have survived for a certain period of time).

After approximately 10 years from treatment, 98% of patients treated with TamRT were free of cancer recurrence, compared to 90% of patients in the Tam group. There was no difference between TamRT and Tam groups regarding DSS (97% versus 98%) and OS (67% versus 66%OS). 

In summary, the addition of RT to breast conserving surgery and tamoxifen improved the risk of developing a recurrence in older patients with early stage ER+ breast cancer. However, this improvement did not appear to give additional survival benefits to these patients.