International Journal of Radiation Oncology*Biology*Physics
Clinical investigationBreastIntensity-Modulated Radiotherapy Results in Significant Decrease in Clinical Toxicities Compared With Conventional Wedge-Based Breast Radiotherapy
Introduction
Breast-conserving therapy with the adjuvant use of radiotherapy (RT) has been established as an effective treatment for early-stage breast cancer with excellent long-term local control and survival (1, 2, 3). However, such RT delivered to the whole breast is not without its associated clinical toxicities. The resultant erythema, edema, skin desquamation, and pain that women can experience while undergoing treatment cannot only have a negative effect on a patient’s quality of life but can also negatively influence a patient’s or physician’s decisions regarding the use of breast conservation and/or in receiving adequate adjuvant treatment (4). Therefore, the ability to potentially reduce the degree of toxicities associated with whole breast irradiation (WBI) is of increasing importance.
Since March 1999, we have been treating patients with early-stage breast cancer with intensity-modulated RT (IMRT) using a static multileaf collimator in an effort to optimize dose homogeneity and decrease normal tissue toxicity. We have previously shown this technique to be an efficient, practical method of delivering breast IMRT in the clinic with similar treatment times to conventional wedge-based treatments. Furthermore, we have demonstrated significantly improved dose homogeneity using this technique with a median of 0.1% of the treatment volume receiving ≥110% of the prescribed dose vs. 10% with conventional wedges (5, 6). It remains to be seen whether the improved dose distribution obtained in our cohort with the elimination of “hot spots” and a lower maximal dose translates into improved clinical outcomes.
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Methods and Materials
A total of 172 patients with early-stage breast cancer (Stage 0-IIB) who were considered acceptable candidates for postlumpectomy RT were identified as eligible for this study. All patients were treated using an alpha-cradle immobilization device with both arms extended above their head. Field borders were designed to encompass the whole breast with the tangent beams aligned so that their deep edges passed through radiopaque markers placed clinically by the physician to define the medial and
Study population characteristics
The patient- and treatment-related characteristics stratified by the type of WBI (WB vs. IMRT) are listed in Table 1. No statistically significant differences were found between the two groups with respect to median follow-up, age at diagnosis, race, stage, tumor size, nodal status, breast volume, or the use of systemic chemotherapy. However, significantly more patients in the IMRT arm were treated with mixed-photon beam energy (6-MV/18-MV) than in the WB group, likely secondary to the use of
Discussion
Although standard WBI results in excellent long-term control and acceptable cosmetic results, many women undergoing RT to the whole breast may unnecessarily experience pain and discomfort secondary to acute and chronic skin toxicity. Previous studies have demonstrated that many of these toxicities can be significantly reduced with more advanced RT delivery techniques. Dose inhomogeneities >10% have been previously demonstrated to correlate with poorer clinical outcomes. Furthermore, such
Conclusion
The improved dose distribution achieved with the use of our IMRT technique for the treatment of the whole breast with adjuvant RT resulted in a significant decrease in acute dermatitis, edema, and hyperpigmentation compared with conventional WB treatment. The development of chronic breast edema was also significantly reduced with the use of IMRT. Patients developing Grade 2 or greater clinical toxicities had larger irradiated breast sizes, on average. The use of IMRT in the clinic is a
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2022, Practical Radiation OncologyCitation Excerpt :Dose to the left anterior descending coronary artery has also been linked with cardiovascular mortality.5 Of additional concern are cosmetic toxicities, such as scarring, which have been associated with dose inhomogeneity.6 Technical advancements have sought to mitigate these toxicities.
Funded in part by a generous gift from the Alfred Berkowitz Foundation and the William Beaumont Hospital Foundation.
Conflict of interest: none.