Clinical investigation
Breast
Intensity-Modulated Radiotherapy Results in Significant Decrease in Clinical Toxicities Compared With Conventional Wedge-Based Breast Radiotherapy

https://doi.org/10.1016/j.ijrobp.2007.02.044Get rights and content

Purpose: We have previously demonstrated that intensity-modulated radiotherapy (IMRT) with a static multileaf collimator process results in a more homogenous dose distribution compared with conventional wedge-based whole breast irradiation (WBI). In the present analysis, we reviewed the acute and chronic toxicity of this IMRT approach compared with conventional wedge-based treatment.

Methods and Materials: A total of 172 patients with Stage 0-IIB breast cancer were treated with lumpectomy followed by WBI. All patients underwent treatment planning computed tomography and received WBI (median dose, 45 Gy) followed by a boost to 61 Gy. Of the 172 patients, 93 (54%) were treated with IMRT, and the 79 patients (46%) treated with wedge-based RT in a consecutive fashion immediately before this cohort served as the control group. The median follow-up was 4.7 years.

Results: A significant reduction in acute Grade 2 or worse dermatitis, edema, and hyperpigmentation was seen with IMRT compared with wedges. A trend was found toward reduced acute Grade 3 or greater dermatitis (6% vs. 1%, p = 0.09) in favor of IMRT. Chronic Grade 2 or worse breast edema was significantly reduced with IMRT compared with conventional wedges. No difference was found in cosmesis scores between the two groups. In patients with larger breasts (≥1,600 cm3, n = 64), IMRT resulted in reduced acute (Grade 2 or greater) breast edema (0% vs. 36%, p <0.001) and hyperpigmentation (3% vs. 41%, p = 0.001) and chronic (Grade 2 or greater) long-term edema (3% vs. 30%, p = 0.007).

Conclusion: The use of IMRT in the treatment of the whole breast results in a significant decrease in acute dermatitis, edema, and hyperpigmentation and a reduction in the development of chronic breast edema compared with conventional wedge-based RT.

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.

Section snippets

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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Funded in part by a generous gift from the Alfred Berkowitz Foundation and the William Beaumont Hospital Foundation.

Conflict of interest: none.

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