METHODS
Simulations and treatment plans were performed with and without the Alderson Treatment Brassiere,
a transparent plastic breast cup designed to shape the breast and reduce field expansion. Dosimetric
parameters were compared between setups.
RESULTS
Eighteen patients with large, pendulous breasts were included. Use of the breast cup significantly reduced
radiation doses to organs at risk, including the lungs and heart. Statistically significant reductions
were observed in lung NTCP (p=0.001), mean lung dose (p<0.001), V20 and V5 (both p<0.001), heart
NTCP (p=0.008), mean heart dose (p<0.001), heart V25 (p<0.001), and LAD dose (p=0.008). Target
coverage remained similar; however, boost D95 (p=0.033) and TCP (p=0.001) improved.
CONCLUSION
Breast cups may enhance RT precision by improving target conformity and reducing critical organ exposure.
Further validation with larger cohorts and modern techniques is warranted.
Keywords: Alderson treatment brassiere; breast cup; breast conservation therapy; immobilization; radiotherapy
A significant clinical gap exists in optimizing
RT positioning for patients with large or pendulous
breasts. Various immobilization techniques-such as
thermoplastic shells, adhesive tape, and wireless bras-
have been introduced to improve positioning. However,
these methods have limitations in standardization,
reproducibility, and patient comfort. While prone
positioning and deep inspiration breath-hold (DIBH)
techniques can reduce radiation exposure to critical organs,
their complexity and setup reproducibility limit
adoption in clinical practice.[
To enhance dose conformality and reduce organ
exposure, advanced RT techniques such as intensitymodulated
RT (IMRT) and volumetric arc therapy
(VMAT) have been implemented. For left-sided breast
irradiation, DIBH increases lung volume, creating additional
separation between the breast and heart, thereby
reducing radiation exposure. However, standardization
challenges remain, particularly in cases requiring
lymph node irradiation.[
A systematic review by Probst et al.[
This study evaluates the dosimetric impact of breast
cups in breast cancer patients undergoing RT, focusing
on their role in minimizing critical organ exposure,
improving target dose conformity, and enhancing
treatment reproducibility.
The breast cups are classified into four size groups and are designed for separate use on the left and right breasts. Each cup is labeled according to size group (S, M, L, XL), body side (R or L). Breast cup selection was based on the patient"s chest breadth (ranging from 27 cm to over 42 cm), with additional markings on the patient's skin to ensure consistent positioning. Small holes in the medial, lateral, and superior areas of the cup flange are used to mark these reference points.
Patients were positioned on a supine breast board with the ipsilateral arm raised. Two sets of CT images were acquired: One with the breast cup and the other without the breast cup.
RT plans were generated for both conditions. If the radiation doses exceed normal tissue tolerances without the breast cup, the patient was treated using the breast cup.
The appropriate cup size was selected based on chest
breadth, and the strap lengths were adjusted to provide full coverage. The straps also exerted gentle pressure on
the contralateral breast, helping to move it out of the radiation
field. Markings were applied to indicate the inner
and outer limits of the cup, along with strap attachment
points, ensuring repeatable positioning (Fig.
Target volumes and organs at risk (OARs) were delineated according to the RTOG atlas consensus guidelines for breast radiotherapy. The clinical target volume (CTV) included the whole breast and, when indicated, the regional lymph node levels (I-III), supraclavicular fossa, and internal mammary chain. A formal planning target volume (PTV) was not generated in accordance with the RTOG atlas; however, for consistency with existing literature, the target parameters were referred to as PTV50 and PTV95% throughout the manuscript.
Patients were treated using conventional inner and outer tangential fields with field-in-field RT. The whole breast received a dose of 50 Gy in a conventional fractionation scheme of 2 Gy per fraction. The boost dose to the surgical cavity ranged from 10 to 16 Gy, depending on the surgical margin status. The Boost Planning Target Volume (Boost PTV) was created by adding a 0.7-1 cm margin around the seroma, clips, and cavity contoured as Boost CTV.
Nodal irradiation to the supraclavicular fossa and axillary levels 1, 2, and 3 was administered using a conventional scheme of 2 Gy per fraction, totaling 50 Gy. The study was approved by the Antalya Training and Research Hospital ethics committee under the rules of Helsinki Convention.
Statistical Analysis
Data was analyzed using the Shapiro-Wilk test to assess
normality. Continuous variables were summarized as mean ± standard deviation for normally distributed
data and as median (IQR: 25th-75th percentile) for nonnormally
distributed data. Wilcoxon Signed Ranks test
and Paired Samples t-test were used to compare dosimetric
differences between treatment plans with and
without the breast cup. Statistical analyses were performed
using IBM SPSS Statistics for Windows, Version
23.0 (IBM Corp., Armonk, NY). A two-sided pvalue
of <0.05 was considered statistically significant.
In this study, PTV50 refers to the planning target volume receiving 50 Gy, which includes the whole breast and regional lymphatics when applicable. PTV95% indicates the volume receiving at least 95% of the prescribed dose. Boost represents the planning target volume of the surgical cavity, typically receiving an additional 10-16 Gy. MI denotes the internal mammary chain target volume when included. Organs at risk (OARs) were delineated, including the ipsilateral lung, contralateral breast, liver, heart, and left anterior descending artery (LAD).
All treatment plans were calculated to meet target coverage criteria. Additionally, Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) values were calculated using the Lyman?Kutcher?Burman (LKB) model, which estimates complication probability based on the dose-volume histogram (DVH) data of each organ. For TCP, the Poisson statistics-based model using the equivalent uniform dose (EUD) method was applied.
Figure
NTCP: Normal tissue complication probability;; TCP: Tumor control probability.
Although contralateral breast dose was reduced with the use of the breast cup, the differences were not statistically significant. Contralateral breast D2 (nearmaximum dose, minimum dose encompassing 2% volume): p=0.306 and, contralateral breast V5 (volume receiving 5 Gy): p=0.554.
However, the breast cup demonstrated significant improvements in key dosimetric parameters:
Reductions in lung dose:
• Mean lung dose: 1481±264 cGy with cup vs.
1884±315 cGy without (p<0.001).
• Lung V5: 39.2±7.9 % vs. 48.3±7.3 % (p<0.001).
• Lung V20: 27.5±5.0 % vs. 36.6±7.0 % (p<0.001).
• NTCP Lung: 3.25 (1.11-6.07) vs. 13.46 (10.27- 34.67) (p=0.001).
Reductions in Heart Dose:
• Heart mean dose: median 856 cGy (523-947) vs.
1307 cGy (1056-1594) (p<0.001).
• Heart V25: 14.7% (8.9-16.9) vs. 24.5% (19.6-32.8) (p<0.001).
• Mean LAD Dose: median 4220 cGy (3057-4625) vs. 4725 cGy (4483-4871) (p=0.008).
• NTCP Heart: 0 vs. 0.03 (0-5.1) (p=0.008).
Reduction in Normal Tissue Dose:
• Normal tissue mean dose: Median 260 cGy (204-
299) vs. 306 cGy (262-360) (p=0.001).
Target Coverage improvements:
• Boost D95: 5967±422 cGy vs. 5884±489 cGy (p=0.033).
• TCP Boost: Median 100 vs. 94.67 (70.18-97.6) (p=0.001).
Compared to prone positioning-which requires
special equipment and trained staff-breast cups offer
a more accessible solution while maintaining reproducibility.
In our study, breast cups narrowed the beam
eye view and lifted the radiation fields away from the
chest wall, effectively reducing doses to the heart and
ipsilateral lung. Although decreases were also seen in
the liver and contralateral breast doses, these were not
statistically significant, likely due to the small sample
size. Nonetheless, the overall reduction in spillage dose
suggests a lowered risk of secondary cancer, aligning
with earlier observations.[
The treatment of women with larger or pendulous
breasts poses unique challenges, especially in supine
positioning, where the breast can shift laterally or upward.
This often increases lung exposure and leads
to dose heterogeneity and hot spots. Previous studies
have linked these variations to breast volume, body weight, and chest wall separation, the latter being
the most influential.[
Concerns about patient discomfort or the need
for manual adjustment have been raised,[
Our results are consistent with emerging evidence
that dedicated immobilization solutions can
significantly improve dosimetry and setup reproducibility
in women with large or pendulous breasts
undergoing radiotherapy. In a recent study, the use
of a radiation-bra device significantly reduced breast
volume as well as mean lung and heart doses in planning
comparisons.[
Taken together, our findings build upon this growing
body of evidence by presenting both dosimetric
and TCP/NTCP modeling results using a breast cup
device in a cohort of patients with pendulous breasts
following breast-conserving surgery. The consistency
of reductions in heart and lung exposure, along with
the associated potential for improved normal tissue
complication probability (NTCP) and tumor control
probability (TCP), supports further prospective research
and encourages routine clinical implementation
of such immobilization techniques in appropriately
selected patients.
The breast cups could also be integrated smoothly
into modern RT protocols, including IMRT, VMAT,
and DIBH. Their potential role in adaptive RT and
compatibility with automated contouring and imageguided
protocols could further highlight their value in
personalized care.
Ethics Committee Approval: The study was approved by the Antalya Training and Research Hospital Clinical Research Ethics Committee (no: 3/1, date: 16/02/2023).
Informed Consent: All patients gave consent to participate after being individually informed. All patient identifiers and data were anonymized.
Conflict of Interest Statement: The authors declare no conflict of interest.
Funding: The authors declared that this study received no financial support.
Use of AI for Writing Assistance: All content was authored by the authors without AI-generated material.
Author Contributions: Concept - S.Ç., A.T.İ.; Design - S.Ç., A.T.İ.; Supervision - S.Ç., A.T.İ.; Funding - S.Ç.; Materials - S.Ç.; Data collection and/or processing - S.Ç., A.T.İ.; Data analysis and/or interpretation - S.Ç., A.T.İ.; Literature search - S.Ç.; Writing - S.Ç.; Critical review - S.Ç., A.T.İ.
Peer-review: Externally peer-reviewed.
