Ongoing clinical experience utilizing 3D conformal external beam radiotherapy to deliver partial-breast irradiation in patients with early-stage breast cancer treated with breast-conserving therapy☆
Received 27 March 2003; received in revised form 23 May 2003; accepted 30 May 2003.
Abstract
Purpose
We present our ongoing clinical experience utilizing 3D conformal radiation therapy (3D-CRT) to deliver partial-breast irradiation (PBI) in patients with early-stage breast cancer treated with breast-conserving therapy.
Methods and materials
Thirty-one patients referred for postoperative radiation therapy after lumpectomy were treated with PBI using our previously reported 3D-CRT technique. Ninety-four percent of patients had surgical clips outlining the lumpectomy cavity (mean: 6 clips). The clinical target volume (CTV) consisted of the lumpectomy cavity plus a 10-mm margin in 9 patients and 15-mm margin in 22 (median: 15 mm). The planning target volume consisted of the CTV plus a 10-mm margin for breathing motion and treatment setup uncertainties. The prescribed dose (PD) was 34 or 38.5 Gy (6 patients and 25 patients, respectively) in 10 fractions b.i.d. separated by 6 h and delivered in 5 consecutive days. Patients were treated in the supine position with 3–5 beams (mean: 4) designed to irradiate the CTV with <10% inhomogeneity and a comparable or lower dose to the heart, lung, and contralateral breast compared with standard whole-breast tangents. The median follow-up duration is 10 months (range: 1–30 months). Four patients have been followed >2 years, 6 >1.5 years, and 5 >1 year. The remaining 16 patients have been followed <12 months.
Results
No skin changes greater than Grade 1 erythema were noted during treatment. At the initial 4–8-week follow-up visit, 19 patients (61%) experienced Grade 1 toxicity and 3 patients (10%) Grade 2 toxicity. No Grade 3 toxicities were observed. The remaining 9 patients (29%) had no observable radiation effects. Cosmetic results were rated as good/excellent in all evaluable patients at 6 months (n = 3), 12 months (n = 5), 18 months (n = 6), and in the 4 evaluable patients at >2 years after treatment. The mean coverage of the CTV by the 100% isodose line (IDL) was 98% (range: 54–100%, median: 100%) and by the 95% IDL, 100% (range: 99–100%). The mean coverage of the planning target volume by the 95% IDL was 100% (range: 97–100%). The mean percentage of the breast receiving 100% of the PD was 23% (range: 14–39%). The mean percentage of the breast receiving 50% of the PD was 47% (range: 34–60%).
Conclusions
Utilizing 3D-CRT to deliver PBI is technically feasible, and acute toxicity to date has been minimal. Additional follow-up will be needed to assess the long-term effects of these larger fraction sizes on normal-tissue sequelae and the impact of this fractionation schedule on treatment efficacy.
*Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, Michigan, USA
†Department of Surgery, William Beaumont Hospital, Royal Oak, Michigan, USA
‡Department of Anatomic Pathology, William Beaumont Hospital, Royal Oak, Michigan, USA
Reprint requests to: Frank A. Vicini, M.D., Department of Radiation Oncology, William Beaumont Hospital, 3601 W. 13 Mile Rd., Royal Oak, MI 48072, USA. Tel: (248) 551-1219; Fax: (248) 551-0089
☆ The authors thank the William Beaumont Hospital Foundation and the Alfred Berkowitz Foundation for their generous support of this research.
ABSTRACT