Arm-Behind-the-Back Position for Breast Cancer Radiotherapy in Patients with Lupus Erythematosus and Shoulder Arthropathy: A Case Report

Introduction

Breast cancer is the most common cancer among women in over 180 countries [1]. For invasive breast cancer, radiation therapy after breast-conserving surgery has been reported to reduce local recurrence and improve survival [2]. However, severe adverse events associated with radiation therapy have traditionally been a concern in patients with collagen vascular disease (CVD) [3], and mastectomy can be the treatment of choice. Recently, the adverse events of radiation therapy in patients with CVD have been found to be less severe than that previously thought [4]. This was no exception for systemic lupus erythematosus (SLE). However, patients with breast cancer and SLE are more likely to undergo mastectomy than breast-conserving surgery and are unlikely to receive radiation therapy [5]. Missed opportunities for breast conservation is a topic of concern for patients with breast cancer and CVD.

Joint symptoms and severity of adverse events can be the reasons for avoiding radiation therapy in patients with CVD. When three-dimensional conformal radiation therapy (3DCRT) is performed in the supine position for breast cancer, patients are required to raise their arms to spare the arms from the irradiation field. However, patients with CVD can experience severe joint symptoms. Maintaining the arm in a raised position can be painful for patients with shoulder joint symptoms. To accommodate these patients, we attempted an arm-behind-the-back (ABB) position, in which a platform was placed between the patient’s body and the couch. In this position, the arm can be dropped behind the back and next to the platform on the couch. This allows 3DCRT to be performed while the arm remains lowered, without interfering with the irradiation field.

We report the case of a patient with breast cancer and SLE who had shoulder joint symptoms on the affected side and underwent breast-conserving surgery and 3DCRT in the ABB position.

Case Report

A 33-year-old woman was referred to our hospital with chief symptoms of facial erythema, bilateral cervical lymphadenopathy, slight fever, and arthralgia. Physical examination revealed a malar rash, oral ulcers, polyarthritis, and alopecia. Computed tomography (CT) revealed organizing pneumonia and enlarged lymph nodes in the mediastinum, abdominal cavity, and both axillae. Based on the above findings and the positive anti-Sm antibody test result, the patient received a diagnosis of SLE. The patient was treated with prednisolone and azathioprine, followed by tacrolimus 1 month later. Six months later, muco-cutaneous symptoms worsened. CT revealed an exacerbation of organizing pneumonia. Syncope was also observed, and the patient was admitted to the hospital. Physical examination revealed myoclonus and cerebellar ataxia. Additionally, anti-DNA antibodies were detected. Based on the results of electroencephalography, single-photon emission CT, and cerebrospinal fluid tests, the patient received a diagnosis of neuropsychiatric SLE. Azathioprine and tacrolimus were discontinued upon the initiation of high-dose prednisolone and intravenous cyclophosphamide therapy. However, she subsequently developed hemophagocytic syndrome, and steroid pulse therapy was initiated, followed by cyclosporine administration. She required 3 months of inpatient treatment. After 6 doses of intravenous cyclophosphamide, the treatment was switched to maintenance therapy with prednisolone, azathioprine, and cyclosporine. Thereafter, the SLE remained stable.

Ten years after the diagnosis of SLE, a localized lesion in the left breast was identified during a medical checkup. The patient had no specific breast-related symptoms. Breast ultrasonography revealed a hypoechoic mass lesion with a diameter of 20 mm and depth/width ratio of 0.5 in the left upper inner quadrant. Contrast-enhanced magnetic resonance imaging revealed a 17 mm mass in the same area. Core needle biopsy yielded a diagnosis of invasive ductal carcinoma, with estrogen receptor >95%, progesterone receptor >95%, and human epidermal growth factor receptor 2 1+. The staging workup with CT and bone scans showed no obvious lymph node or distant metastasis (cT1cN0M0 stage IA, according to the 8th edition of the Union for International Cancer Control TNM classification). No BRCA1/2 variants were identified. At the time of breast cancer diagnosis, immunological examinations revealed no hypocomplementemia or elevation of anti-DNA antibodies, and SLE was considered stable. Azathioprine was discontinued before the start of breast cancer treatment. Breast-conserving surgery was performed, with cyclosporine withdrawal during the perioperative period. The intraoperative frozen section analysis of the sentinel lymph nodes was negative for metastasis. The histopathological diagnosis was invasive ductal carcinoma, with no lymphatic or vascular invasion, no ductal spread, negative resection margin, histological grade I, estrogen receptor >95%, progesterone receptor >95%, human epidermal growth factor receptor 2 1+, and Ki-67 labeling index 23% (pT1cN0M0 stage IA according to the 8th edition of the Union for International Cancer Control TNM classification). After surgery, oral tamoxifen was administered. SLE disease activity remained stable after surgery.

The patient developed adverse events related to SLE and received steroid therapy. Adverse events included bilateral osteo-necrosis of the femoral head and left humeral head (Figure 1). We performed CT simulations for 3DCRT using a 16-slice scanner (Optima CT580 W, GE Healthcare, Milwaukee, WI, USA), with a slice thickness of 2.5 mm. Initially, we performed CT simulation in a regular supine position. However, because of pain, the patient had difficulty holding her left arm in a raised position. Therefore, with the patient’s consent, we decided to try the ABB position, in which a platform was placed between the patient’s body and the couch (Figure 2). A headrest pillow was used for position fixation. The patient was positioned supine, ensuring the left edge of the patient’s trunk was positioned on the left edge of the platform. The left arm was lowered onto the couch and was in contact with the side of the platform. Accordingly, the left shoulder joint was adducted as much as possible. Skin markings were made on the patient’s trunk and left upper arm. To include the left arm in the scan area, the field of view of the CT scan was set to 600 mm (512×512 matrix and 1.2 mm/pixel). We developed treatment plans for each of the regular supine (Figure 3A, 3B) and ABB (Figure 3C, 3D) positions and reviewed the differences between the plans. In both plans, (1) the clinical target volume was the left conserved breast, (2) the planning target volume (PTV) was created for the prescription volume by trimming a 0.5 cm body surface from the clinical target volume, (3) the plan consisted of 2 tangential irradiation fields using 4 MV X-ray and field-in-field technique, and (4) the prescribed dose was defined as the mean dose to the PTV. The details of both plans are presented in Table 1. The treatment plan in the ABB position had an acceptable homogeneity index, low dose to the lungs and heart, and no problematic hotspots (Figure 4). Therefore, we adopted the plan for the ABB position.

Treatment was administered using a linear accelerator (CLINAC 21EX-S, Varian Medical Systems, Palo Alto, CA, USA). The prescribed dose was 42.56 Gy in 16 fractions. Laser matching was used to check the trunk position and the left arm lowering, that is, the shoulder joint extension angle. Additionally, position matching was performed using the edges of the light field and electronic portal imaging devices. Throughout the irradiation period, the time required for position matching and irradiation of the patient averaged approximately 20 min/day. However, on days when the setup had to be repeated or the yaw angle had to be adjusted, the time sometimes exceeded 30 min. Grade 2 radiation dermatitis with bright erythema was observed. Dimethyl isopropylazulene and steroid ointments were used to treat dermatitis. After the end of irradiation, dermatitis peaked on day 14 and mildly resolved thereafter. After 7 weeks, the redness of the skin had disappeared, leaving light pigmentation. The patient showed no signs of local recurrence or distant metastasis 15 months after 3DCRT. No radiation pneumonitis was observed.

Discussion

This is the first report of a patient with breast cancer and a history of severe SLE who underwent radiation therapy in the ABB position after breast-conserving surgery. Although the patient had a history of severe SLE and was unable to keep her left arm raised because of arthritis, radiation therapy was safely completed, with mild adverse events. In the present case, the ABB position for radiotherapy after breast-conserving surgery led to a reduction in shoulder pain and favorable dose distribution.

The incidence of severe toxicity after radiation therapy in patients with CVD has been increasingly reported to be acceptably low [4]. In addition, dose fractionation has been reported to have a limited effect on post-irradiation adverse events in patients with breast cancer and CVD [6]. We prescribed a hypofractionated dose of 42.56 Gy in 16 fractions, and no grade 3 or higher adverse events were observed. Grade 2 radiation dermatitis with bright erythema was observed. However, dermatitis eventually resolved, resulting in light pigmentation. Because of the aforementioned traditional concerns for patients with CVD, a history of severe SLE can lead to the decision not to administer radiation therapy. However, the risk should be evaluated in light of the current status of SLE, and the possibility of breast conservation should be considered. Discussing the possibility of breast conservation with surgeons, oncologists, and rheumatologists after confirming a patient’s desire for breast conservation can help improve the quality of life of patients.

The novelty of the ABB position lies in the placement of the platform underneath the body. This allows the upper arm to escape backward from the irradiation field in 3DCRT, even in patients who are unable to raise their arms. In the normal arm-down position, where the body and arms are on the same plane, the upper arm is irradiated in 3DCRT to such a depth that the irradiation reaches the humerus [7]. In the ABB position, the triangular exposure area on the upper front of the arm is small (Figures 3, 4). This allows a uniform dose within the PTV to be obtained using 2 tangential fields. The ABB position had a higher homogeneity index and lower mean dose to the lungs and heart than the regular supine position. This may be due to the roll rotation of the chest with the lateral part hanging downward, or due to the lateral backward traction of the thorax by the pectoralis major muscle. Whether this trend is observed in other patients requires further investigation. Moreover, fixation accuracy, reproducibility, and simplicity of patient positioning must be addressed in the future. There is scope for enhancement of fixation devices and position-matching methods. Additionally, care must be taken to ensure that the fixation devices do not contact the linac gantry. Despite these challenges, a 3DCRT plan can be devised, with the patient in the ABB position.

The appropriate platform height is a crucial issue for the ABB position. We adopted a platform height of 9 cm. However, the appropriate height can vary from patient to patient. The platform should be higher to prevent the arm from entering the irradiation field. However, there is a risk of shoulder injury due to hyperextension. Factors that govern the platform height include trunk thickness and width, arm thickness and width, the angle of extension of the shoulder joint, and the field angle of the incident ray. In addition to these factors, establishing an acceptable cephalocaudal length of the triangular exposure area on the arm is required. Moreover, elastic distortions of the body and joints should be determined. These distortions complicate the creation of a mathematical model to calculate the appropriate height, as observed in the present case. Increasing the number of documented cases and collecting numerical data can facilitate the construction of an empirical model to determine the appropriate height of the platform. This topic needs to be addressed in future investigations on the ABB position.

Conclusions

We encountered a patient with breast cancer and SLE who had shoulder joint symptoms and completed 3DCRT in the ABB position after breast-conserving surgery. The treatment plan achieved a reduction in shoulder pain and favorable dose distribution. The ingenuity of positioning can lead to the achievement of radiotherapy in patients with CVD and shoulder joint symptoms.