Pattern and distribution of bone metastases in common malignant tumors

Bone scan is a sensitive but not specific method for evaluation of bone metastases. However, the clinical data and the pattern of bone scan findings help the physician to narrow the diagnostic differentials. We tried to investigate the distribution of bone metastases in common cancers using bone scintigraphy.

160 consecutive patients with malignancy (prostate cancer: 32, breast cancer: 107, lung cancer:8, and gastrointestinal cancers: 13) underwent bone scan.

From the 160 patients, 58 patients (36.3%) had abnormal bone scans attributable to metastatic tumor. Bone metastases were found in 32.7%, 40.6%, 38.5% and 62.5% of patients with breast, prostate, GI and lung cancers, respectively (P = 0.35). The most frequently involved area was the spine, followed by ribs and pelvic bones. Spine was the most frequent site of bone metastases in breast and GI cancers. Except for the spine, common locations of bone metastases from breast cancer were ribs and sternum. In prostate cancer, the most frequent site were spine and pelvis, with similar incidences. In lung cancer, ribs followed by spine were most frequent sites of bone metastases. 97 (60.6%) of the cancer patients studied had symptoms of bone pain. The highest incidence was associated with metastatic lesions in bone scan (P = 0.004). Significant correlation between location of bone pain and evidence of bone metastasis in the same region was noticed in the pelvis (P =0.001), skull (P = 0.04), sternum (P = 0.01), spine (P = 0.003) and femur (P < 0.001).

Our results indicate that the spine and pelvis in prostate carcinoma and the spine, ribs and sternum in breast carcinoma as well as ribs and spine in lung cancer are most frequently invaded. Bone pain in the skull, sternum, lumbar vertebrae, pelvis and proximal portion of femurs are more important to keep in mind for metastatic bone involvement.