Abstract
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 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.
Highlights
Breast radiation therapy (RT) treatment planning for node positive disease has involved creating a standard two-dimensional (2DRT) wedged plan on a single transverse contour taken through the center of the breast and matched to a single anterior field to encompass the supraclavicular-axilla dosed to a depth of 3 cm [1]
In comparison to the intensity modulated RT (IMRT)/Tomotherapy reports, our study demonstrated in a large number of cases (n = 262) that using established does-volume goals to meet target coverage and avoidance of organs at risk (OAR) is achievable with 3D conformal radiotherapy (3DCRT)
Any retrospective analysis for breast RT of this type has limitations: 1) The variability introduced in the RT planning process wasn’t discussed in the literature until 2007-2009, which makes it difficult to assess the impact of this effect on our results; 2) Contouring databases, like the Radiation Therapy Oncology (RTOG) breast atlas, were not published until 2009, making it more difficult to assess differences in contouring in our analysis; and 3) The heart was not contoured for all whole breast/chest wall (WB/CW) cases
Summary
Breast radiation therapy (RT) treatment planning for node positive disease has involved creating a standard two-dimensional (2DRT) wedged plan on a single transverse contour taken through the center of the breast and matched to a single anterior field to encompass the supraclavicular-axilla dosed to a depth of 3 cm [1]. Other disease sites have demonstrated an improvement in the therapeutic ratio using three dimensional conformal RT (3DCRT) or intensity modulated RT (IMRT), where the internal/external anatomical tissues/ organs are delineated and used in treatment planning. Contouring atlases for breast have been developed and the use of dose-volume goals has become a standard element of RT planning for patients on more recent Radiation Therapy Oncology (RTOG) and National Surgical Adjuvant Breast and Bowel Project (NSABP) breast clinical trials [4] [5]. The purpose of this work is to retrospectively evaluate the plan quality of NPBC patients since our institution standardized the use of dose-volume goals (referred to as goals hereafter) in treatment planning of NPBC
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