Role of Whole-Body Tc 99m MDP Bone Scintigraphy for Evaluating Skeletal Metastasis in Patients with Lung Cancer

Abstract

Lung cancer is the third most common site of origin of metastatic cancer deposits in bone, after breast and prostate. Its metastasis to bone is one of the most aggressive tumors and has a very unfavorable prognosis.  This retrospective descriptive study was designed to detect the skeletal metastasis of   carcinoma (Ca) lung patient by Tc 99m MDP bone scan. The medical records of all patients attended between January 2015 and July 2015 with a diagnosis of lung cancer were reviewed. Lung cancer in all patients was confirmed pathologically, and patients underwent whole-body bone scan for evaluating skeletal metastasis.  Patient with clinical and laboratory evidence of infection, trauma, metabolic disease or arthropathy were not included in the study. Bone scan was done after three hours of   intravenous administration of 20mci Tc 99m MDP   (methylene diphosphonate) and images were obtained on a gamma camera.  The mean age of the patients was Mean ± SD was 55.5 ± 12.5   with range from 31 to 90 years.  Out of 47 cases, 36 (76.59%) were diagnosed as positive for skeletal metastasis by bone scan and 11 (23.41%) were negative for bony metastasis. Among 36 positive patients, 28 patients (77.86%) were histopathologically diagnosed as adenocarcinoma, 7 patients (19.44%) had squamous cell carcinoma and only one patient (2,7%) had small cell carcinoma. Bone scan findings were compared by either conventional X-ray/CT scan/MRI /pathologically. In present study, the distribution of lesions in bone scan had recorded. Maximum 47.22 % lesions were found in ribs, 27.77% lesions were in lumbar vertebrae, 19.44% in thoracic vertebrae, 19.44% in joints, 16.66% in long bones (femur and humerus), 11.11% in skull bones, 22.22% in pelvic bones, 5.55% in clavicle and 2.77% in scapula. Tc 99m MDP bone scan plays a pivotal role for detection of skeletal metastasis which is very essential to manage Ca lung patient. As bone scintigraphy is very cost effective in govt. nuclear medicine centre in comparison to other imaging modalities, so it can play a major role in detecting skeletal metastasis in ca lung patients in a developing country like Bangladesh.