Hyperthermia and radiation therapy for locally advanced or recurrent breast cancer

Abstract

631 Background: Hyperthermia is a known radiation sensitizer. This retrospective series evaluates a single institutional experience with hyperthermia and radiotherapy (RT) for locally advanced/recurrent breast cancer, many referred for palliation. Methods: Records of 130 pts with locally advanced/recurrent breast cancers treated with hyperthermia and RT from 1991–2007 were reviewed. 40% had distant metastases. 168 different sites were irradiated to 16–76.4 Gy (median 50 Gy) with conventional fractions and treated with 1–11 hyperthermia sessions twice/wk (median 6). 58 pts required >1 hyperthermia field to cover tumor. Intratumoral temperature goal was >42.5°C for >45 min. Thermal equivalent dose (TED) was calculated for each treatment (min above 42.5 and 43°C). Results: Median and mean FU of alive patients was 20 and 32 mos, respectively. 27 pts were treated for locally advanced and 103 for recurrent cancer on the chest wall, nearby skin, or nodes. Treated sites were: intact breast (21%), chest wall/skin (66%), nodes (12%). Disease volume was microscopic in 11%, less than 3 cm in 11%, and greater than in 78%. Various concurrent chemotherapy regimens were given in 56%. 40% of treated sites had prior RT (median 50 Gy). CR was seen in 52% and CR/PR in 79% in pts with measurable tumor. 5 mastectomies were done, with no residual cancer in 1. Local control (LC) at last FU was obtained in 58% of treated sites. Type (primary vs recurrent), location (breast/chest wall/node), extent of disease (3 cm), or prior RT were not associated with LC. Improved LC was seen with increased RT dose, 36%, 52%, and 70% for 16–39.6 Gy, 40–50 Gy, and 50+ Gy, respectively. LC also improved with more minutes of hyperthermia - median of 238 min and 147 min TED 42.5°C & 43°C, respectively in pts with LC, and median of 180 min and 105 min TED 42.5°C and 43°C, respectively in pts without LC. All pts with microscopic disease are controlled. 16 pts (12%) are NED (mean 32 mos). Conclusions: Hyperthermia and RT improves local control and can palliate locally advanced or recurrent breast cancer, even in previously irradiated pts - a quality of life issue. Although the followup of this poor prognosis group is short, local control appears to be maintained to death for many pts. Pts with microscopic residual cancer after resection may benefit from the combination. No significant financial relationships to disclose.