Age-stratified risk of unexpected uterine sarcoma following surgery for presumed benign leiomyoma.

BACKGROUND: Estimates of unexpected uterine sarcoma following surgery for presumed benign leiomyoma that use age-stratification are lacking. PATIENTS AND METHODS: A retrospective cohort of 2,075 patients that had undergone myomectomy was evaluated to determine the case incidence of unexpected uterine sarcoma. An aggregate risk estimate was generated using a meta-analysis of similar studies plus our data. Database-derived age distributions of the incidence rates of uterine sarcoma and uterine leiomyoma surgery were used to stratify risk by age. RESULTS: Of 2,075 patients in our retrospective cohort, 6 were diagnosed with uterine sarcoma. Our meta-analysis revealed 8 studies from 1980 to 2014. Combined with our study, 18 cases of leiomyosarcoma are reported in 10,120 patients, for an aggregate risk of 1.78 per 1,000 (95% confidence interval [CI]: 1.1-2.8) or 1 in 562. Eight cases of other uterine sarcomas were reported in 6,889 patients, for an aggregate risk of 1.16 per 1,000 (95% CI: 0.5-4.9) or 1 in 861. The summation of these risks gives an overall risk of uterine sarcoma of 2.94 per 1,000 (95% CI: 1.8-4.1) or 1 in 340. After stratification by age, we predict the risk of uterine sarcoma to range from a peak of 10.1 cases per 1,000, or 1 in 98, for patients aged 75-79 years to <1 case per 500 for patients aged <30 years. CONCLUSION: The risk of unexpected uterine sarcoma varies significantly across age groups. Our age-stratified predictive model should be incorporated to more accurately counsel patients and to assist in providing guidelines for the surgical technique for leiomyoma.