Comparative Analysis of the Post-Lumpectomy Target Volume Versus the Use of Pre-Lumpectomy Tumor Volume for Early-Stage Breast Cancer: Implications for the Future

Purpose Three-dimensional conformal accelerated partial breast irradiation (APBI-3D-CRT) is commonly associated with the treatment of large amounts of normal breast tissue. We hypothesized that a planning tumor volume (PTV) generation based on an expansion of the pre-lumpectomy (pre-LPC) intact tumor volume would result in smaller volumes of irradiated normal breast tissue compared with using a PTV based on the post-lumpectomy cavity (post-LPC). Use of PTVs based on the pre-LPC might also result in greater patient eligibility for APBI-3D-CRT. Methods and Materials Forty-one early-stage breast cancers were analyzed. Preoperative imaging was used to determine a pre-LPC tumor volume. PTVs were developed in the pre- and post-LPC settings as per National Surgical Breast and Bowel Project (NSABP)-B39 guidelines. The pre- and post-LPC PTV volumes were compared and eligibility for APBI-3D-CRT determined using NSABP-B39 criteria. Results The post-LPC PTV exceeded the pre-LPC PTV in all cases. The median volume for the pre- and post-LPC PTVs were 93 cm3 (range, 24–570 cm3 ) and 250 cm3 (range, 45–879 cm3 ), respectively, p