Does radiotherapy with electrons boost during surgery reduce the risk of breast cancer recurrence?

The authors investigated whether intra-operative electron radiotherapy (IOERT) boost reduces breast cancer recurrence compared to standard radiotherapy. They found that IOERT slightly reduced cancer recurrence compared to standard external beam radiotherapy (EBRT).

Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer death in women. Great improvements have been made in breast cancer treatment. Early-stage breast cancer therapies include lumpectomy (removal of the tumor while preserving the breast) and whole-breast irradiation (WBI). In patients with high risk for local recurrence, a treatment option consists of removing the tumor and immediately administrate a boost of radiotherapy.

Standard radiotherapy boost involves delivering radiation to the tumor bed from outside the body. This is called external beam radiotherapy (EBRT). Another option is delivering radiation directly during surgery. This treatment is called intraoperative radiotherapy (IORT). A newer type of IORT involves electron radiation (IOERT) that is more precise and avoids harming healthy nearby tissues.

However, it is not known whether applying IOERT followed by standard WBI can help reducing toxicity and improve the general outcome of the treatment of patients with early-stage breast cancer compared to standard WBI followed by EBRT.

235 patients with breast cancer were enrolled in the study. All patients underwent lumpectomy as the first treatment option. The patients were next divided into two groups. The first group (125 women) received IOERT at the same time as surgery. The second group (110 women) received standard EBRT. Both groups also received WBI. Patients were followed up for an average of 12 years.

After 10 years, breast cancer recurrence was observed in fewer patients in the IOERT group compared to standard EBRT (4.3% vs 5.3%). IOERT-treated patients had recurrences after more than 100 months after the treatment. In comparison, the recurrence in the standard EBRT group was at an average of 55.2 months. 

The overall survival rate after 10 years was similar between the IOERT group (91.6%) and the EBRT group (94.3%).

Cosmetic outcomes (how the breast looked after treatment) were significantly better at all follow-up times in the IOERT group compared to the EBRT group.

This study concluded that IOERT tended to reduce cancer recurrence compared to standard EBRT with better cosmetic outcomes in patients with early-stage breast cancer.

No information on the type of cancer was given. This might affect how a cancer responds to treatment.