Proposing the 3-tier staging system for improving prognostication in Stage I uterine leiomyosarcoma.

BACKGROUND AND OBJECTIVES

To examine the utility of a 3-tier schema (≤5 cm, 5.1-10 cm, and > 10 cm) in determining characteristics and survival in Stage I uterine leiomyosarcoma.

METHODS

This retrospective observational study queried the National Cancer Institute's Surveillance, Epidemiology, and End Result Program from 1988 to 2016. Surgically treated stage I uterine leiomyosarcomas with known tumor size were examined (N = 2217). Trends, characteristics, and survival were assessed based on tumor size.

RESULTS

The most common tumor size was 5.1-10 cm (45.7%) followed by >10 cm (35.0%) and ≤5 cm (19.4%). Tumor size-shift occurred during the study period; the percentage of tumor size >10 cm increased from 12.9% to 44.5% and the groups with smaller tumor sizes decreased (p < .001). In weighted models, 5-year overall survival rates ranged from 49.9% to 71.6% in the 3-tier system and 55.2%-70.6% in the 2-tier system: the absolute difference was larger in the 3-tier system (21.7% vs. 15.4%). In the 3-tier system, all-cause mortality risk of tumor size >10 cm versus ≤5 cm nearly doubled (hazard ratio 1.96, 95% confidence interval 1.78-2.16).

CONCLUSION

In the past decades, tumors of stage I uterine leiomyosarcoma have become larger. Our study suggests that a tumor size-based 3-tier staging system may be useful to differentiate survival in stage I uterine leiomyosarcoma.