Session Item

Mastectomy is standard for recurrence of breast cancer after breast conservation therapy (BCS) with whole breast irradiation (WBI). Reirradiation poses a distinct therapeutic challenge owing to risks associated with exceeding normal tissue tolerances and possibly more therapeutically resistant disease biology. Partial breast irradiation (PBI) has emerged as a viable alternative to whole breast irradiation in selected patients undergoing initial breast conservation. We report our experience with partial breast reirradiation (PBrI) for local recurrent breast cancer.

All patients with locally recurrent breast cancer, who underwent external beam radiotherapy with PBI until February 2021 at our institution were identified. For each case of reirradiation, demographic, disease characteristics, prior and reirradiation radiotherapy details, toxicity and outcome were collected. Freedom from locoregional recurrence and distant metastasis were calculated using the Kaplan-Meier method.

Nine patients received BCS plus PBrI for isolated local recurrence. The median prior radiotherapy treatment was WBI with prescribed dose to the breast of 50 Gy (IQR, 48-60 Gy), 9 patients performed 3DCRT technique and 1 patient boost with brachytherapy . The majority (5 patients) had tumor localized on left breast and in the upper outer quadrant.

The median time from prior radiotherapy to reirradiation was 89 months (IQR, 28-238 months). Three patients received chemotherapy. The most common reirradiation radiotherapy dose/fractionation was 40 Gy/2.67 Gy fractions per day.  One patient received 38.5Gy/3.85 Gy fractions BID.

Median reirradiation radiotherapy dose was 40 Gy (IQR, 38.5-60 Gy) in 2.67 Gy/fx (IQR, 2.0-3.85 Gy).

There was 1 case of acute grade 3 toxicity: rib fracture in a patient that received 38.5 Gy/3.85 Gy BID. There were no cases of wound dehiscence.

Median follow-up was 19.5 months (IQR, 1-52 months) with one patient showing local recurrence 5 months and another patient with distant progression 3 months after reirradiation. Eighteen months after reirradiation one patient showed local and distant progression.

The 1 year local relapse-free survival was 87.5% and 1 year distant disease-free survival was 85.7%.

Partial breast reirradiation for local breast cancer with external beam radiotherapy is well tolerated with a low rate of severe acute toxicity. Mature follow-up is needed to adequately characterize the late toxicity. Local control with this approach is excellent.