LMOD1 expression and survival in uterine leiomyosarcoma: discordant results in tissue microarrays and whole sections

BACKGROUND: Leiomodin 1 (LMOD1) was previously reported to be associated with longer survival in leiomyosarcoma (LMS) in analysis combining uterine and non-uterine tumors. The objective of the present study was to analyze the expression and prognostic role of LMOD1 in a large series of exclusively uterine LMS (uLMS). METHODS: LMOD1 protein expression by immunohistochemistry was analyzed in tissue microarrays (TMAs) from 244 uLMS and whole sections from 203 uLMS, of which 134 were included in both series. Expression was assessed for association with clinicopathologic parameters and disease-specific survival (DSS). RESULTS: TMAs were informative in 221/244 (91%) tumors, of which 100 (45%) expressed LMOD1. No significant association with DSS was observed for 156 patients with clinical data. In the series stained using whole sections, LMOD1 was expressed in 142/203 (70%) tumors, and higher expression was associated with significantly longer survival (203 patients with survival data; p=0.007). Other parameters related to survival in the latter series were FIGO stage (p<0.001), tumor diameter (p<0.001), mitotic count (p<0.001), the degree of atypia (p=0.006) and lymphovascular invasion (LVSI; p=0.006). In Cox multivariate analysis, FIGO stage (p<0.001), mitotic count (p<0.001), tumor diameter (p=0.001) and LMOD1 expression (p=0.003) were independent prognosticators. CONCLUSIONS: LMOD1 expression in whole sections is a new candidate marker of longer survival in uLMS. This study additionally highlights the limitations associated with use of TMA sections compared to whole sections in biomarker studies.