Soft Tissue Sarcoma of Extremities: Descriptive Epidemiological Analysis According to National Population-based Study

Background: Soft-Tissue Sarcoma (STS) is a heterogeneous group of neoplasms of mesenchymal origin, occurring in connective tissues. According to previously conducted studies, STS accounts for approximately 1% and 7-%15% of adult and pediatric malignancies, respectively. Almost 50%-60% of sarcomas arise from extremities and usually present as a large painless or rarely painful soft-tissue mass. The present study aimed to describe the epidemiology of soft-tissue sarcomas, especially in the Iranian population. Methods: This epidemiological study of limb soft-tissue sarcoma was conducted based on Iran National Cancer Registry data (INCR) between 2009 and 2014. Patients with soft-tissue sarcoma confirmed by histopathological studies were included, and data were classified based on the International Classification of Diseases for Oncology (first revision-third edition [ICD-O-3]) and analyzed. Descriptive analysis was performed to extract age-standardized and age-specific incidence rates. Results: A total of 2, 593 patients (1,476 males and 1,117 females) were enrolled and assessed in the present study. The age-standardized incidence rate(ASIR) of total soft tissue sarcomas was 6.34 per million person-years. In addition, the highest and lowest ASIR scores stratified by age were observed in patients aged above 65 and under 0 with the value of 19.61 (95% CI:17.91-21.30) and 1.91 (95% CI 1.69, 2.13) per million, respectively. Limb soft tissue sarcomas stratified by gender were dominant in males, and it was statistically significant (P<0.05). The most common extremity soft tissue sarcomas subtypes were mesenchymal tumor (12.26%), spindle cell sarcoma (12.18%), and malignant fibrous histiocytoma (11.45%). Conclusion: As evidenced by the results of the present study, the ASIR of soft tissue sarcoma dramatically increased with age, and the peak ASIR occurred in the age range of above 65 years. The incidence rate of soft tissue sarcomas analyzed by disease site was higher in hip and lower limb than upper limb and pelvis region, and it was detected consistently in all age groups and both genders.