Abstract
This study aimed to investigate the effects of tumor-rib distance and dose-dependent rib volume on radiation-induced rib fractures (RIRFs) in patients with breast cancer. We retrospectively included 510 women with breast cancer who underwent surgical resection with adjuvant radiotherapy. The tumor-rib distance was measured using preoperative computed tomography (CT) images. Postoperative chest wall thickness and dose-dependent rib volumes, which are absolute rib volumes receiving >20 Gy (V20), 30 Gy (V30), 40 Gy (V40), 45 Gy (V45), and 50 Gy (V50), were measured from the stimulation CT images for radiation treatment planning. We assessed the relationship of RIRF with tumor-rib distance, postoperative chest wall thickness, and dose-dependent rib volumes. Patients with high values of tumor-rib distance and postoperative chest wall thickness had significantly lower risks of RIRF than those with low values. Patients with high values of V20, V30, V40, V45, and V50 had significantly higher risks of RIRF than those with low values. In a multivariate analysis, tumor-rib distance and all five dose-dependent rib volumes, as well as osteoporosis and radiation field, were independent risk factors for RIRF. Tumor-rib distance and dose-dependent rib volume were independent risk factors for RIRF in patients with breast cancer.
Highlights
Worldwide, breast cancer has the highest incidence and mortality rates among cancers in women [1]
radiation-induced rib fractures (RIRFs) is characterized by abnormal findings on bone scintigraphy, which is often used for follow-up surveillance of patients with breast cancer, and these abnormal findings can be misdiagnosed as bone metastasis [9,10,12]
The exclusion criteria were as follows: the patients (1) who had distant metastasis on staging work-up examinations, (2) who showed bone metastasis on follow-up imaging studies, (3) who had a history of radiotherapy in the breast or chest wall owing to metachronous breast cancer, (4) who had a history of other malignant diseases, and (5) who were lost to follow-up within 24 months after radiotherapy
Summary
Breast cancer has the highest incidence and mortality rates among cancers in women [1]. Resection of primary breast cancer lesions with surgical axillary staging is the standard curative treatment for patients with breast cancer [2]. For patients treated with either breast conservative surgery or mastectomy, adjuvant radiotherapy is recommended to eradicate any remaining tumor cells [2]. Adjuvant radiotherapy has an established crucial role in the curative management of patients with breast cancer, showing survival benefits of reducing recurrence rates and improving overall survival in a meta-analysis study including more than 10,000 patients [3,4]. Adjuvant radiotherapy involves several complications that have been receiving increased attention considering increased survival periods among patients with breast cancer [5,6]. Radiation-induced rib fracture (RIRF) is one of the well-known adverse effects of conventional radiotherapy in patients with breast cancer, with an occurrence rate of 1.0–18.5% [4,7–10]. Several studies have tried to identify the risk factors for RIRF among radiotherapy-related factors and clinical factors [7–9,12]
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