Comparing long-term outcomes of whole or partial breast irradiation after breast-conserving surgery

This study compared whole breast irradiation (WBI) to partial breast irradiation (PBI) following breast-conserving surgery (BCS) in patients with low-risk breast cancer. The study showed similar survival between the 2 treatments, while PBI gave better cosmetic results.

Patients with low-risk breast cancer can undergo BCS which involves the surgical removal of the tumor, rather than the full breast. BCS is commonly followed by radiation therapy (RT) to reduce the risk of relapse. RT can be given to the whole breast (WBI) or to the part of the breast where the tumor was (PBI). PBI can be given to the patient either by external beam irradiation (EBI) or by inserting an implant into the breast where the tumor was (brachytherapy; BT).

Studies have been carried out to test the safety and effectiveness of PBI and WBI. However, the long-term impact of PBI and WBI has not been reported.

This study included 258 patients with low-risk breast cancer. Patients had BCS and then were randomly assigned to two groups. Group 1 received WBI. Group 2 received PBI, either by implant (BT) or by EBI. 72% of group 1 and 70% of group 2 were then given chemotherapy and/or hormone therapy. The average follow-up time was 17 years.

After 20 years, local recurrence occurred in 7.9% of group 1 and 9.6% of group 2. Group 1 had an overall survival rate of 59.7% compared to 59.5% in group 2 after 20 years. 78.3% of group 1 and 79.7% of group 2 were alive with no disease progression after 20 years.  

79.2% of group 2 had a good/excellent cosmetic outcome compared to 59.5% of group 1. In group 2, 82.4% of the patients who received BT and 72.5% of those treated with EBI had an excellent/good cosmetic outcome.

11.8% of group 1 and 13.6% of group 2 experienced late skin reactions.

This study showed that PBI and WBI after BCS led to similar long-term survival in patients with low-risk breast cancer, while patients treated with BT-PBI experienced a better cosmetic result.

The sample size of the study was quite small. The technology used to give patients WBI has advanced in the last 20 years.