Impact of adjuvant radiation therapy photon energy on quality of life after breast conservation therapy: Linear accelerator versus the cobalt machine

Abstract

Breast conservative therapy (BCT) is a standard treatment option in early operable breast cancers (OBC) and a select group of large or locally advanced tumors. The present study deals with prospective evaluation of quality of life (QOL) score in consecutive patients treated with BCT employing adjuvant RT treated with either a cobalt machine or a linear accelerator (LA). Patients of carcinoma breast who underwent BCT were taken into the study. Patients with larger breasts (inter-field separation >18-20 cm) were treated on LA and those with smaller breasts were treated on cobalt machine. All patients received a uniform RT dose (45-50 Gy/25#/5 weeks) to whole breast followed by tumor bed boost with suitable energy electrons. Prospective evaluation of QOL was done using EORTC QLQ C30 and breast cancer-specific EORTC QLQ BR23. QOL evaluation was done at pre-RT, at half completion of RT treatment (at 20-23 fractions) and at completion of RT. Pre-RT evaluation GQOL scores in patients treated with cobalt and LA were 71.6 and 71.7, respectively (P = 0.8). QLQ C30 functional and symptom domain scores were also similar in the groups. At RT completion, Global quality of life (GQOL) scores were 67.7 in patients treated with cobalt as compared to 77.7 in patients treated with LA (P = 0.75). Physical function domain scores in cobalt and LA patients were 70.8 and 80.3, respectively (P = 0.26). Fatigue score was higher in patients treated with cobalt (39.1 versus 29.7; P = 0.9). However, there was no difference in other functional and symptom domains. There was no significant change in any of the EORTC QLQ C30 domains at RT completion as compared to the pre-RT scores. There is no significant difference in QOL domains between appropriately selected patients treated with cobalt and LA. There are no significant changes in QOL domain scores at RT conclusion as compared to pre-RT baseline in patients treated with cobalt or LA source. A cobalt machine may be effectively used to deliver adjuvant RT in appropriately selected BCT patients especially in developing countries with limited resources.