Abstract P4-11-21: Dosimetric Comparison of Radiotherapy for Left Sided Breast Cancer: Breath-Hold Versus Free-Breathing

Abstract Background: Radiotherapy for left sided breast cancer potentially increases risk for late toxicity to the heart. The simple technique of breath-hold (BH) can be instituted in an attempt to reduce volume of lung and heart irradiated in tangential fields. We report on patients with left sided breast cancer that were planned both with conventional free-breathing (FB) and BH radiation techniques from a single institution. Methods: From 10/2006 to 5/2010, 20 patients with node-negative, early stage breast cancer underwent CT simulation for left sided breast cancer and were selected for analysis in this report. FB and BH CT scans were obtained and treatment plans using opposed tangential fields were created to compare various dosimetric indices. Results: BH plans resulted in lower doses to the heart (max dose 1774 vs. 4560cGy, P&amp;lt;0.0001; mean dose 175 vs. 296cGy, p=0.0178; V25 0 vs. 1.85%, P&amp;lt;0.0001; volume in tangential field 0 vs. 10.11cc p=0.0002) compared to FB. The ipsilateral lung received lower doses but a larger volume of lung was encompassed in the tangential fields (V20 13.32 vs. 20.32%, P&amp;lt;0.0001; mean dose 741 vs. 1025cGy, p=0.0003; volume in tangential field 198.8 vs. 256.8cc P&amp;lt;0.0001) compared to FB. Conclusions: Treatment of early stage left sided breast cancer with BH technique is a simple method for minimizing cardiac and ipsilateral lung dose. Long term follow-up is necessary to demonstrate if these dosimetric differences translate into clinically meaningful differences. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-11-21.</jats:p