Study of distribution of bone metastases in metastatic breast cancer patients compared to other major cancers

Abstract

INTRODUCTION For metastatic carcinomas, skeletal metastases are the third most common following pulmonary and hepatic. In addition, bone metastases may present as the first manifestation of cancer in 25-30% of cases 1. The most common malignant tumors that metastasize to bone are prostate cancer in males and breast cancer in females and lung cancer in both. Also, any malignant tumor can metastasize to bone 2. Studying the pattern of distribution of skeletal metastases can help in diagnosis and narrow the diagnostic differentials. This study aimed to assess the pattern of bone metastases in breast cancer patients compared to other common cancers using Technetium-99m-methylene diphosphonate skeletal scintigraphy. Besides, to explore if there is a specific distribution of bony deposits in breast cancer patients compared to other major malignancies in order to reduce diagnostic differentials. METHODS We studied whole-body bone scans of 150 cancer patients which was done to exclude or assess metastatic bone disease. Anterior and posterior views were obtained with a dual detector gamma camera for patients who had undergone scintigraphy with Tc-99m methylene diphosphonate (600 MBq Tc-99m MDP). Bone scans were interpreted as positive for bone metastasis if radiotracer activity of local bone lesion was greater or less than that of adjacent or contralateral normal bone. Introduction: Metastatic bone disease is frequent in patients with advanced breast cancer. Although it is not specific for the detection of metastatic bony lesions, bone scan is a sensitive method. The pattern of distribution of bone metastases as detected by bone scan combined with clinical data may help in reaching diagnosis. Methods: Technetium-99m-methylene diphosphonate skeletal scintigraphy was used for evaluation of distribution pattern of skeletal metastases in patients with breast carcinoma compared to other common cancers. Results: Out of 134 patients with positive bone scan for skeletal deposits, the primary cancer was breast cancer in 81 patients, prostate in 24, lung in 12, liver in 8, urinary bladder in 6, and head and neck in 3. Few metastases (≤ 3 deposits) were common in breast cancer, while extensive metastatic lesions (≥10 deposits) were more common in prostate cancer (50%). The most common locations of bone metastases in patients with breast cancer were the spine, pelvic bones, femora, and ribs, respectively. In prostate cancer patients, spine was the most common site of metastases, especially the lumber region. In lung cancer patients, thoracic spine was the most common site of metastases, while pelvic bones were the most common site in liver cancer patients. Conclusion: In breast cancer, the most frequent sites of involvement are the spine (especially lumber region), pelvis and axial skeleton, respectively. Spinal and sternal involvements are significantly more in breast cancer than in other malignancies.