Introduction We investigated whether two-step testing strategies – consisting of multiplex ligation-dependent probe amplification, somatic mutation screening in cancer tissues, and microsatellite instability analysis – can improve the detection of LS in this clinical population. We also compared the clinical characteristics and overall survival (OS) of women with and without a final diagnosis of LS.

Methods A total of 31 Taiwanese women with synchronous or metachronous endometrial and colorectal malignancies underwent both universal screening – consisting of immunohistochemistry for mismatch repair protein expression, MLH1 promoter methylation analysis, and germline mutation testing – and two-step testing for the detection of LS.

Results On applying traditional universal screening, the prevalence of LS in the study patients was 16.1% (5/31). Interestingly, the application of extensive two-step molecular testing was able to identify three previously undetected cases. Patients with and without LS in our cohort did not differ significantly both in terms of clinical characteristics and OS.

Conclusion/Implications The application of extensive two-step molecular testing may increase the identification of cases that have been previously undetected on traditional universal screening. Patients with and without LS were found to be similar both in terms of clinical characteristics and OS.