Patterns of pathologically confirmed metastasis to bone in Near East population.

Background: Metastatic tumors to bone constitute the majority of bone malignancies. The site of metastasis to bone and the prognosis depend chiefly on the primary tumor. Despite all the advances in diagnostic techniques, identifying the primary tumor has not improved significantly.

Methods: A total of 576 cases (Lebanon; n = 306, Pakistan; n = 270) presenting with microscopic evidence of metastasis to bone were reviewed between 1996 and 2016. Clinical and radiologic data were recorded.

Results: Out of 20 types of primary tumors, unknown primary (38.2%), followed by breast (23.8%), lung (10.4%) and thyroid (4.9%) tumors were the most commonly presenting with bone metastasis. The primary source of the tumor showed significant correlation with the site of metastasis, time lag to metastasis and radiologic presentation (p < 0.001). Interestingly, a significant variation was noted between the 2 observed populations.

Conclusion: The patterns of pathologically confirmed metastasis to skeletal sites in Near East population showed a special distribution, and variation was even observed between the 2 studied centers. Understanding the biologic variations of the primary tumors in our population may further explain the variation in patterns of metastasis.