Interstitial vs. Intracavitary Brachytherapy and Repeat Lumpectomy for In-breast Tumor Recurrence following Breast Conserving Therapy and Whole Breast Irradiation: A Comparison of Techniques

Abstract

To compare low dose rate interstitial brachytherapy to high dose rate intracavitary brachytherapy for IBTR re-treated by lumpectomy. Between 1/1998 and 11/2008, 32 patients with TIS to T2 (< 3 cm) breast carcinoma were offered brachytherapy following failed BCT and WBI (range 4500 - 6600 cGy) as an alternative to salvage mastectomy. One additional patient developed an in-field breast cancer following full mantle irradiation (4500 cGy) for Hodgkin's Lymphoma 27 years prior. All tumors were re-excised with negative margins per National Surgical Adjuvant Breast and Bowel Project (NSABP) definition. Following repeat lumpectomy, tumor bed implantation was carried out utilizing a low dose rate (LDR) interstitial technique (4500 -5530 cGy at 35 - 50 cGy per hour to the tumor bed plus a 1.0 cm margin) in 23 patients. Five patients were treated with high dose rate (HDR) brachytherapy (3400 cGy twice daily at 340 cGy/fx according to NSABP B-39/ RTOG 0413 protocol) using the MammoSite system and five were treated using the Contura multi-lumen system. Maximum skin and rib dosages in the patients treated with the Contura system were additionally compared using the central lumen of the catheter in a multi-dwell idealized delivery against a multi-lumen delivery. Two patients (LDR group) developed grade III acute complications by the Common Terminology Criteria for Adverse Events (v. 3.0). Four patients (HDR group) developed grade I acute complications. With the Contura® system, the mean reduction in maximum skin and rib doses was 12.2% and 13.9% respectively (range: 0- 43.7%) compared to MammoSite. With skin and rib distances of less than 1 cm, the mean dose reductions were 18% and 33.6% respectively. NSABP cosmesis grading scores were: Grade I in 25 patients (including the 10 MammoSite and Contura patients), Grade II in 2 patients, Grade III in 3 patients, and was unavailable for 3 patients. 32 of 33 patients remain free of local failure with a mean follow-up of 24.9 months (range 1 - 90.6 months). Repeat BCT and brachytherapy radiation for IBTR is a feasible process. HDR intracavitary brachytherapy has decreased acute toxicities compared to LDR interstitial brachytherapy. The Contura device provides noticeable skin and rib dose reductions. The long term cosmetic effect of HDR intracavitary compared to LDR interstitial brachytherapy following repeat lumpectomy for IBTR is superior. HDR intracavitary brachytherapy and repeat lumpectomy is a reasonable alternative for the treatment of IBTR.