Unresectable bulky chest wall recurrent breast cancer controlled with CT-guided interstitial high-dose-rate brachytherapy and external beam radiotherapy with adjuvant hormonal therapy - case report

Abstract

Purpose: Bulky chest wall recurrence after mastectomy presents a therapeutic challenge because of high-dose of radiation required to control the disease, and its proximity to low-tolerance organs at risk. We report a case of successful computed tomography (CT)-guided high-dose-rate (HDR) salvage interstitial brachytherapy (ISBT) boost.

Material and methods: A 70-year-old female initially presented with a tumor in right breast, and was treated with mastectomy and adjuvant chemotherapy, followed by hormonal therapy for 5 years without adjuvant radiotherapy. In 2018, 20 years after the initial treatment, she developed unresectable chest wall recurrence that measured 10.5 cm × 7.3 cm × 4.5 cm, with bone and parietal pleura invasion. Biopsy revealed invasive pleomorphic lobular carcinoma [estrogen receptor (ER)-positive, progesterone receptor (PR)-negative, HER2-negative]. There was no evidence of metastatic disease.

Results: The patient underwent external beam radiotherapy (EBRT) plus ISBT. After EBRT of 50 Gy in 25 fractions was completed, CT-guided ISBT was performed as an outpatient treatment. HDR dose was 16 Gy delivered in 2 fractions with 2 implants. Dose was prescribed to gross tumor volume. ISBT plans were created using inverse planning simulated annealing (IPSA) algorithm. Gross tumor volume D_90% plus EBRT dose was 82 Gy equivalent dose of 2 Gy (EQD₂), assuming α/β of 4 for breast carcinoma. The patient continued on hormonal therapy. At the 30-month follow-up, the patient remains in remission. The tumor could not be detected by magnetic resonance imaging (MRI) or positron emission tomography (PET). There were no severe treatment-related complications.

Conclusions: CT-guided HDR ISBT boost can be a useful modality in individualizing treatment strategies for breast cancer patients with unresectable bulky chest wall recurrence.

Keywords: breast cancer; interstitial brachytherapy; unresectable recurrent cancer.

Fig. 1

Dose distribution in external beam radiotherapy (EBRT) planning. In this EBRT plan, the lung V_5Gy and V_20Gy (i.e., the percent volumes of both lungs receiving 5 Gy and 20 Gy, respectively) were 20% and 13%, respectively, and the mean heart dose was 5.6 Gy

Fig. 2

Implantation of brachytherapy flexible catheters (A) and flexible catheters fixed with dental putty (light blue) (B). The putty was sutured to the skin using a thread (white arrow) to avoid catheter’s displacement. Catheters were attached to the putty using instant glue (tip of black arrow) to strengthen the fixation further

Fig. 3

Axial (A) and coronal (B) CT images of the gross tumor volume (GTV; red dashed lines), including the sternum lesions receiving 4 Gy (blue lines), 8 Gy (red lines), and 12 Gy (white lines). The catheters were implanted, penetrating the tumor and reaching the front of the sternum. The dental putty can also be seen (white arrows)

Fig. 4

Axial ¹⁸F-FDG-PET/CT image before radiotherapy (A), axial plain CT image before the second interstitial brachytherapy (ISBT) (B), enhanced axial CT image at 6 months (C), and axial 18F-FDG-PET/CT image at 26 months (D). The bulky tumor with bone invasion (A, white arrows) on the right chest wall decreased in size (B and C, white arrows) and finally disappeared (D, white arrows)

Fig. 5

Axial (A) and sagittal (B) T2-weighted MRI before radiotherapy. Axial (C) and sagittal (D) T2-weighted MRI at 28 months. The bulky tumor with bone invasion (A and B, white arrows) on the right chest wall disappeared (C and D, white arrows)

Fig. 6

The right chest wall at 30 months. Telangiectasia is apparent on the skin surface