[1187] Small (≤ 5 cm) Uterine Leiomyosarcomas Are Rare, Frequently Misdiagnosed and as Clinically Aggressive as Larger Tumors

R Soslow, M Leitao, O Zivanovic, L Jacks, M Hensley, E Veras. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: The literature suggests that low grade, young age (≤ 50 years) and small tumor size (≤ 5 cm) are all associated with improved outcomes in patients with uterine leiomyosarcoma (LMS). The FIGO 2009 staging system considers organ confined LMS < 5 cm as stage IA and implies more favorable outcomes.
Design: We identified all cases of LMS seen at our institution from 7/82-7/07. Tumor size was dichotomized into 2 groups (≤ 5 cm and >5 cm). Cases were staged according to FIGO 1988 after adaptation for use in sarcoma. Two pathologists reviewed all available hysterectomy specimen slides from tumors in the former group.
Results: We identified 268 cases. The median age was 51 y (range 23-81 y). 55% were stage I, 6% stage II, 18% stage III and 21% stage IV. Primary tumor size was available in 95% of cases (n=254). The median follow-up was 39.7 months. After excluding cases diagnosed as "low grade LMS" (n=5), there were 123 FIGO stage I cases, 23 of which were ≤ 5 cm. The overall survival for ≤ 5 cm tumors was 77 months (95% CI: 0-169.2 months) compared to 73.9 months (95% CI: 55.9-91.9 months) for larger tumors (p=0.3). Slides were available for re-review in 15 of 23 cases. An LMS diagnosis was upheld in 13 of 15 cases; 1 case was considered a STUMP and the other an undifferentiated sarcoma.
Conclusions: LMS measuring ≤ 5 cm constitute less than 10% of all LMSs. Excluding cases diagnosed as "low grade LMS," many of which are not LMSs, yields an even smaller cohort. The remaining cohort resembles the much more common group of LMSs >5 cm and had similar clinical outcomes. These data do not support substaging for small LMS in FIGO 2009.
Category: Gynecologic & Obstetrics

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 149, Wednesday Morning


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