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.
OBJECTIVE
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
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 cm(3) (range, 24-570 cm(3)) and 250 cm(3) (range, 45-879 cm(3)), respectively, p <0.001. The difference between pre- and post-LPC PTVs represented a median of 165 cc (range, 21-482 cc) or 16% (range, 3%-42%) of the whole breast volume. Three of 41 vs. 13 of 41 cases were ineligible for APBI-3D-CRT when using the pre- and post-LPC PTVs, respectively.


CONCLUSIONS
PTVs based on pre-LPC tumor expansion are likely associated with reduced amounts of irradiated normal breast tissue compared with post-LPC PTVs, possibly leading to greater patient eligibility for APBI-3D-CRT. These findings support future investigation as to the feasibility of neoadjuvant APBI-3D-CRT.
Nichols
Elizabeth M
EM
Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Dhople
Anil A
AA
Mohiuddin
Majid M
MM
Flannery
Todd W
TW
Yu
Cedric X
CX
Regine
William F
WF
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D005240:Feasibility Studies; D005260:Female; D005544:Forecasting; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D015412:Mastectomy, Segmental; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods; D009367:Neoplasm Staging; D011300:Preoperative Care; D011859:Radiography; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods; D012189:Retrospective Studies; D047368:Tumor Burden