Evaluating the role of radiotherapy in HER2+ early-stage breast cancer after breast-conserving surgery

The study evaluated the effectiveness of radiotherapy (RT) in patients with HER2+ early-stage breast cancer (BC) after breast-conserving surgery (BCS). The study found that RT improved the survival rates of these patients, especially for those high-risk.

BC is categorized based on the absence or presence of protein receptors found on the surface of cancer cells. HER2+ is a protein found in cancer cells and promotes their growth. This subtype has various treatment modalities such as chemotherapy, targeted therapy, endocrine therapy, radiation therapy, and surgery.

BCS involves removing the tumor only while preserving the remaining breast. The need for RT after BCS in early-stage BC patients is still unclear. Clinical trials have shown that RT could reduce recurrence risk and improve overall survival. However, although RT is well tolerated, not every patient benefits from it. Some experience adverse events such as breast pain, skin abnormalities, and heart and lung toxicity. Furthermore, HER2+ subtype BC is the most resistant subtype to RT and may only have limited survival benefits. Therefore, the role of RT in HER2+ early-stage BC treated with BCS is still unclear.

The study analyzed a total of 10799 patients with early-stage HER2+ BC who received BCS. Patients were put in 2 groups. Group 1 (7554 patients) received RT, and group 2 (3245 patients) did not receive RT. The average follow-up time was 29 months.

Patients in group 1 were 72% more likely to have improved overall survival compared to group 2. Patients in group 1 also were 70% more likely to have improved breast cancer-specific survival. 

In patients with high-risk BC, RT was significantly associated with a better overall survival (by 60%) and BC-specific survival (by 61%) compared to the non-RT group. In patients with intermediate risk, RT improved BC-specific survival (by 16%) but there was no improvement in overall survival compared to the non-RT group. 

The study concluded that RT after BCS for HER2+ early-stage BC improved the outcomes of patients with high-risk BC compared to those who did not receive RT. 

The follow-up period was short. A longer follow-up study is needed to validate the findings. Also, the study was based on medical records. There were differences in the other therapies patients received.