Use of Three Dimensional Conformal Radiation Therapy for Node Positive Breast Cancer Does Not Result in Excess Lung and Heart Irradiation

Purpose: This work evaluates the use of target and organs at risk (OAR) dose-volume goals in 3D conformal radiotherapy (3DCRT) planning for node positive breast cancer (NPBC) patients undergoing regional nodal irradiation after lumpectomy/mastectomy. Methods: Dosimetric data for 262 NPBC patients receiving regional nodal and whole breast/chest wall (WB/CW) irradiation from 2000-2009 were analyzed. In all cases, target & OAR volumes were delineated on treatment CT scans for field generation and dose-volume histograms (DVHs) were generated. Cases were analyzed to identify how frequently they met treatment planning institutional dose-volume goals (“institutional guidelines” & standardized in 2005) and how this would affect OAR doses. Results: The incidence of cases from 2000-2009 meeting current institutional guidelines improved over the study period. Target coverage improved from 2005-2009, when guidelines were followed as a part of the plan approval. Those cases from 2000-2004 meeting acceptable target goals were found to be significantly different from those cases from 2005-2009 (p < 0.01). However, no significant difference between cases meeting OAR goals for plans from 2000-2004 versus 2005-2009 was found. Conclusions: The use of institutional guidelines in 3DCRT for WB/CW and regional nodal irradiation for NPBC patients improved target coverage without a statistically significant increase in heart and lung doses.