Evaluation on Bra usage for breast cancer radiotherapy: OARs sparing and acute skin reaction
Sin Ting Chiu,
Hong Kong (SAR) China
PO-1844
Abstract
Evaluation on Bra usage for breast cancer radiotherapy: OARs sparing and acute skin reaction
Authors: Sin Ting Chiu1, Sze Ming Wong1, Sze Wan Kong1, Wing Yiu Lee1, Ka Fai Cheng1, George Chiu1
1Hong Kong Sanatorium & Hospital, Department of Radiotherapy, Hong Kong, Hong Kong (SAR) China
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Purpose or Objective
Radiotherapy is part of the common treatment regime for Ca Breast Patient. During the radiotherapy treatment, patient is usually treated without wearing any bra or clothes. The breast tissue was treated in nature position without any immobilization device. In recent year, a commercial FDA-approved bra is available for the use in radiotherapy treatment. This study aims to evaluate the Chabner® XRT bra in the term of dosimetric effect on OARs (heart and ipsilateral lung) sparing and the seriousness of acute skin reaction.
Material and Methods
OARs Sparing
Female breast cancer patients with a self-reported breast cup size of B or above, who haven’t undergone mastectomy, were recruited prospectively for this study. With the consent of patient, two set of CT images (with and without bra) were taken for treatment planning. All borders were defined by a single oncologist. Two treatment plans (with and without bra) using 2-field tangential opposing technique were computed for dosimetric comparison. The maximum lung depth, the field length and DVH parameters, including Dmean of heart, V20, V10 and V5 of ipsilateral lung, were used for comparison.
Acute Skin Reaction
All breast cancer patients underwent 2-field tangential breast conformal radiotherapy from 2019-2021 at Hong Kong Sanatorium & Hospital were recruited retrospectively. Their acute radiation-induced skin reactions were compared between patients treated with bra and without bra using the acute radiation morbidity scoring criteria (Grade 0-4) suggested by RTOG, which the detail is shown as follows.
0 | No change over baseline |
1 | Follicular, faint or dull erythema/epilation/dry desquamation/ decreased sweating |
2 | Tender or bright erythema, patchy moist desquamation/ moderate edema |
3 | Confluent, moist desquamation other than skin folds, pitting edema |
4 | Ulceration, haemorrhage, necrosis |
Table 1: The acute radiation morbidity scoring criteria (Grade 0-4)
Results
A total of 18 treatment plans from 9 patients (6: Ca Rt Breast; 3: Ca Lt Breast) were computed and used for dosimetric comparison. For patients with bra, the inferior border shifted 1.2 cm superior and the lateral border shifted 0.8cm on average. The maximum lung depth decreased 0.3cm (2 vs 2.3cm; p=0.03). The V20, V10, V5 of ipsilateral lung has a significant 3.6%, 3.7% and 3.8% decrease respectively (p<0.01). The mean dose of heart was also decreased 1Gy on average (p=0.09).
Between 2019 and 2021, 288 patients were treated with 2-field tangential breast conformal radiotherapy in 15fractions. 18 patients were treated with bra. There was no significant difference found on the acute skin reaction in the last treatment (p>0.05). No patient suffered from grade 3 or 4. Only 4 of patients with bra experienced grade 2 skin reaction at the last treatment.
Table 2: The acute radiation morbidity score distribution based on the weekly skin reaction assessment from 288 treatment patients
Conclusion
The usage of bra lowered the radiation dose to both heart and ipsilateral lung without additional skin toxicity.