Bone Marrow Metastasis Is an Early Stage of Bone Metastasis in Breast Cancer Detected Clinically by F18-FDG-PET/CT Imaging

OBJECTIVE To determine the value of 18F-FDG PET/CT in detection of bone marrow (BM) metastasis in breast cancer which is considered an early stage of bone metastasis. PATIENTS AND METHODS Retrospectively, breast cancer patients with bone metastasis were included. BM metastasis was considered if the lesion was PET positive/CT occult while bone metastasis was considered if the lesion was PET positive/ CT positive. BM metastases were observed sequentially on F18-FDG PET/CT. RESULTS We included 35 patients. Eighteen patients (51%) had BM metastases in addition to other bone metastases. BM metastases comprised 24% of all lesions. Posttreatment scan was performed on 26/35 patients. Twenty-three percent of BM metastases had resolved completely without causing bone destruction after treatment. Sixty-five percent of BM metastases had converted into bone metastases after treatment. Twelve percent of BM metastases had persisted after treatment. CONCLUSION This retrospective study showed clinically by 18F-FDG PET/CT imaging that BM metastasis is an early stage of bone metastasis in breast cancer. Interestingly, 18F-FDG-PET/CT showed that early eradication of individual BM metastasis by systemic treatment precluded development of bone metastasis. However, more research is needed to study the impact of an early diagnosis of BM metastases on treatment outcome.