Clinical Investigation
Prone Whole-Breast Irradiation Using Three-Dimensional Conformal Radiotherapy in Women Undergoing Breast Conservation for Early Disease Yields High Rates of Excellent to Good Cosmetic Outcomes in Patients With Large and/or Pendulous Breasts

Preliminary versions of this study were presented at the American Radium Society 2009 Annual Meeting, April 25-29, Vancouver, BC, and the American Society for Radiation Oncology 2009 Annual Meeting, November 1-5, Chicago, IL.
https://doi.org/10.1016/j.ijrobp.2011.08.020Get rights and content

Purpose

To report our institution's experience using prone positioning for three-dimensional conformal radiotherapy (3D-CRT) to deliver post-lumpectomy whole breast irradiation (WBI) in a cohort of women with large and/or pendulous breasts, to determine the rate of acute and late toxicities and, more specifically, cosmetic outcomes. We hypothesized that using 3D-CRT for WBI in the prone position would reduce or eliminate patient and breast size as negative prognostic indicators for toxicities associated with WBI.

Methods and Materials

From 1998 to 2006, 110 cases were treated with prone WBI using 3D-CRT. The lumpectomy, breast target volumes, heart, and lung were contoured on all computed tomography scans. A dose of 45–50 Gy was prescribed to the breast volume using standard fractionation schemes. The planning goals were ≥95% of prescription to 95% of the breast volume, and 100% of boost dose to 95% of lumpectomy planning target volume. Toxicities and cosmesis were prospectively scored using the Common Terminology Criteria for Adverse Effects Version 3.0 and the Harvard Scale. The median follow-up was 40 months.

Results

The median body mass index (BMI) was 33.6 kg/m2, and median breast volume was 1396 cm3. The worst toxicity encountered during radiation was Grade 3 dermatitis in 5% of our patient population. Moist desquamation occurred in 16% of patients, with only 2% of patients with moist desquamation outside the inframammary/axillary folds. Eleven percent of patients had Grade ≥2 late toxicities, including Grade 3 induration/fibrosis in 2%. Excellent to good cosmesis was achieved in 89%. Higher BMI was associated with moist desquamation and breast pain, but BMI and breast volume did not impact fibrosis or excellent to good cosmesis.

Conclusion

In patients with higher BMI and/or large–pendulous breasts, delivering prone WBI using 3D-CRT results in favorable toxicity profiles and high excellent to good cosmesis rates. Higher BMI was associated with moist desquamation, but prone positioning removed BMI and breast size as factors for poorer cosmetic outcomes. This series adds to the growing literature demonstrating that prone WBI may be advantageous in select patients.

Introduction

The majority of patients with early-stage breast cancer are candidates for breast-conservation therapy (BCT). Several large randomized control trials comparing BCT with mastectomy have demonstrated no difference in locoregional control, disease-free survival, or overall survival (1). These large studies have all been conducted using whole-breast irradiation (WBI) delivered in the supine position. However, supine breast WBI does have limitations. Irradiation after breast-conserving surgery (BCS) in women with large and/or pendulous breasts can be particularly challenging. Several institutions have shown increased radiation-related toxicities and worse cosmetic outcomes for patients with large, pendulous breasts and/or increased body mass index (BMI) undergoing BCT 2, 3, 4, 5, 6, 7, 8, 9. Radiation factors identified as potentially causative include increased dose inhomogeneity from medial to lateral separation of the breast and bolus effect on skin, including the inframammary folds, where there is increased skin-on-skin contact. In addition, patients with large breasts may receive increased doses to critical structures such as the heart or lungs owing to the positioning of the breast on the chest wall when the patient lies supine. Prone breast irradiation aims to improve on some of the technical limitations associated with treating large, pendulous breasts and/or large body habitus, and it may also assist in limiting radiation doses to organs at risk 10, 11, 12, 13, 14, 15.

Our institution developed a method for delivering breast three-dimensional conformal radiotherapy (3D-CRT) in the prone position to address the technical challenges associated with irradiation of large and/or pendulous breasts. The goal of this study was to report our institution's experience using prone positioning in a cohort of women receiving postlumpectomy WBI, to determine the rate of acute and late toxicities and, more specifically, cosmetic outcomes. We hypothesized that the use of 3D-CRT for WBI in the prone position would reduce or eliminate patient and breast size as negative prognostic indicators for toxicities associated with WBI.

Section snippets

Study population

Between 1998 and 2006, 109 women (110 breasts treated) underwent WBI in the prone position using 3D-CRT. One patient had a history of Hodgkin's disease treated with radiation to the mediastinum. All other patients were treated prone secondary to a large body habitus and/or large–pendulous breasts. The median follow-up was 40.3 months (mean 45.9 months, range 1–127 months) for living patients. One hundred five patients had 1 year or more of clinical follow-up (median 43.1 months, mean 47.4

Study population

The individual characteristics of the patient population are summarized in Table 1. Median age of the patients (n = 110 cases) was 61.0 years. Seventy-five percent of patients were clinically obese (BMI ≥30 kg/m2), with a median and mean BMI of 33.6 kg/m2 and 34.6 kg/m2, respectively. The majority of patients also had large and/or pendulous breasts, with a median breast volume of 1396 cm3 and 80% of patients with breast volumes of ≥1000 cm3.

Tumor and treatment characteristics

Table 1 summarizes the tumor and treatment

Discussion

Breast-conserving treatment has allowed many women to receive appropriate breast cancer management with long-term local control and survival rates equivalent to those with mastectomy, while maintaining a cosmetically acceptable breast appearance. Unfortunately, women with larger breasts can be technically challenging to treat with breast irradiation, resulting in higher rates of severe acute dermatitis and late fibrosis causing unacceptable cosmesis. Our institution has developed prone breast

References (35)

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    In the remaining 45 studies (25.4%), evaluating the incidence of pain was not the primary focus. Twenty-three studies (13.6%) explored the efficacy of different radiation techniques and associated outcomes [15–37]; 7 studies (4.0%) focused on quality of life (QoL) [38–44]; 7 articles (4.0%) assessed the efficacy of intervention or rescue treatments [45–51]; 1 study (0.6%) reported on skin toxicities and cosmesis outcomes post-radiotherapy [52]; 3 (1.7%) evaluated the prognostic significance of symptoms as predictors [53–55]; 3 (1.7%) reported on the validation or effectiveness of screening tools [56–58]; and 1 study (0.6%) compared symptom-reporting between patient and physician post-radiotherapy [59]. One hundred seventy-seven studies described pain prevalence and severity post-BC therapy (Table 11).

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Supported in part by Grant No. 1UL1RR031973 from the Clinical and Translational Science Award program of the National Center for Research Resources, National Institutes of Health.

Conflict of interest: none.

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