Occult Leiomyosarcomas in a Canadian Province: A Retrospective Cohort Study.

OBJECTIVE: The risk of unexpected uterine leiomyosarcoma (LMS) following surgery for presumed benign leiomyoma is quoted to be between 1 in 498 and 1 in 5000. The objectives of the present study were to determine the prevalence of uterine LMS in a specific patient population and the rate of diagnosis of occult uterine LMS and to evaluate the risk of unintended morcellation of LMS in Saskatchewan.

METHODS: This study was a Canadian Task Force Classification II-2 multicentre retrospective cohort study in academic-affiliated tertiary care centres. All women with the histopathologic diagnosis of uterine LMS in Saskatchewan between January 2000 and December 2014 were included. Women with metastatic LMS at diagnosis or other types of uterine sarcomas were excluded. Data including patients' characteristics, clinical presentation, physical examination findings, imaging, pathology reports, surgical interventions, and survival outcomes were reviewed.

RESULTS: A total of 28 patients had a confirmed histopathologic diagnosis of LMS over the 15-year study period. Approximately 26 212 hysterectomies were performed in Saskatchewan over the same time frame. The prevalence of uterine LMS in this patient population over the study time frame is estimated to be one in 853. Mean age at diagnosis was 53.8 ± 10.0. Medical records of 25 patients could be retrieved, and 15 cases (60%) had an occult diagnosis. There were five cases of unintended morcellation (one power, four mechanical). Survival outcomes were comparable in women with unintended morcellation of occult disease and in those without morcellation.

CONCLUSION: This study contributes to the existing body of literature on morcellation of occult LMS, and it ascertains the rate of LMS in a patient population. The results of this study provide valuable information to health care professionals, policy makers, and women in Saskatchewan so that they may make more informed decisions concerning uterine masses.