Background
There is no validated system to identify prognostically distinct cohorts of women with uterine leiomyosarcoma (ULMS). Using an independent, pooled, multi-institutional, international patient cohort, we validated a recently proposed ULMS nomogram.
Methods
The ULMS nomogram incorporates 7 clinical characteristics (age, size, grade, cervical involvement, locoregional metastases, distant metastases, and mitotic index (per 10 HPF) to predict overall survival (OS) following primary surgery. Independent cohorts from two sarcoma centers were included. Eligible women underwent at minimum a hysterectomy for primary, locally advanced, or metastatic ULMS and received part of their care at one of the centers between 1994 and 2010.
Results
We identified 187 women with ULMS who met the above criteria (median age, 51 years; median tumor size, 9 cm; median mitotic index, 20). Tumors were generally high grade (88%), FIGO stage I-II (61%) without cervical involvement (93%) and without locoregional (77%) or distant metastases (83%). Median OS and the 5-year OS rate were 4.5 years (95% CI 3.2–5.3) and 46%, respectively; 65 women (35%) were alive at last follow-up. The nomogram concordance index was 0.67(SE=0.02), which was as high as the concordance index from the initial cohort used for nomogram development. The concordance between actual OS and nomogram predictions suggests excellent calibration since predictions were within 1% of actual 5-year OS rates for patients with a predicted 5-year OS of less than 0.68.
Conclusions
The ULMS nomogram was externally validated using independent cohorts. These findings support the international use of the ULMS nomogram prognostic of OS in ULMS.
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