873 - Comparison of interstitial brachytherapy with volumetric modulated arc therapy for tumour bed boost following breast conservative surgery

Background

Tumour bed boost irradiation is an integral part of breast conservative treatment. The various techniques for delivering tumour bed boost include electrons, photons, and interstitial brachytherapy. Volumetric modulated arc therapy (VMAT) is a novel radiation treatment technique. The purpose of the study is to compare high dose rate (HDR) interstitial brachytherapy (BT) with VMAT for tumour bed boost following breast conservative treatment in terms of local control, acute skin toxicity and cosmesis.

Methods

50 patients with early stage breast cancer [Stage I-II] who underwent breast conservation surgery were randomized to either HDR interstitial brachytherapy group (n = 25) or VMAT group (n = 25) for tumour bed boost. All patients in both groups received whole breast irradiation of 46Gy in 23 fractions. The patients in the brachytherapy group received perioperative interstitial HDR BT of 15Gy in 6 fractions over a period of 3 days as boost and whole breast irradiation was delivered after a gap of 2-3 weeks. For patients in the VMAT group, irradiation to the whole breast was delivered first, followed by sequential tumour bed boost of 16Gy in 8 fractions. Chemotherapy and hormonal therapy were given as indicated. Local control, acute skin toxicity and breast cosmesis were assessed.

Results

At a median follow up of 8.5 months, there were no local recurrences observed in both the arms. The acute skin toxicity was similar in both the groups. No grade 4 toxicity was observed; one patient in each group developed grade 3 toxicity. At 3 months, the rate of excellent/good cosmesis was similar for the 2 groups by observer evaluation. According to patient self-evaluation, breast cosmesis was rated as excellent/good in 84% of patients treated with VMAT and 92% of patients treated with HDR BT.

Conclusions

Both modalities of tumour bed boost irradiation were similar in local control, acute skin toxicity and cosmetic outcome. VMAT has the advantage of better patient acceptance as it is non-invasive and less painful when compared to interstitial brachytherapy. Studies with higher sample size and longer follow up are needed to quantify the absolute benefit of each modality with respect to local control and breast cosmesis.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

Institute Ethics Committee, JIPMER.

Funding

JIPMER Intramural research fund.

Disclosure

All authors have declared no conflicts of interest.