Breast Sarcoma Incidence Rate: A National Study in Iran

Background: Breast sarcomas are a group of rare and non-epithelial malignancies that account for less than 1% of breast cancers. There are few epidemiologic studies on this type of cancer due to its rarity. Methods: In this study, the database of the Iran National Cancer Registry (INCR) from March 2009 to March 2014 was used to calculate the age-specific incidence rate for breast sarcoma in Iran. Moreover, age-standardized incidence rate (ASR) for pathologic subtypes, pathologic grades, and different regions of the country were determined. Results: Totally, 258 breast sarcoma patients were included in this study in Iran. The ASR of breast sarcoma was 1.17 (95% CI: 1.02,.32) and 0.60 (95% CI: 0.52, 0.67) per million person-years for women and the total population, respectively. ASR was 0.03 (95%CI: 0.01, 0.06) per million person-years for male patients. The highest age-specific incidence rate for malignant phyllodes was observed among patients aged 55 to 59 years (1.0; 95% CI: 0.5, 1.5), and for other sarcomas, it was found among those aged 70 to 74 years (0.9; 95% CI: 0.2, 1.6). The most prevalent pathologic grade of sarcoma was grade 3 with an ASR of 0.40 (95% CI: 0.34, 0.46) per million person-years. Conclusions: Compared to western countries, Iran has a lower incidence of breast sarcoma in women, a higher incidence rate in men, and older onset age. As in other countries, malignant phyllodes tumors and angiosarcomas are the most common subtypes. In addition, breast sarcoma incidence rates in different grades are similar across countries.