Introduction Universal tumour-based screening using immunohistochemistry (IHC) analysis has been recommended and implemented as a standard of care in patients with endometrial cancer (EC); however, few such studies have been published on Canadian cohorts. This study used a pilot screening programme to identify Lynch syndrome (LS) among newly diagnosed patients with EC in Saskatchewan and identify factors influencing the uptake of genetic counselling and testing to inform future oncology or specialist-led testing. Methods 48 patients with endometrial cancer were enrolled in ‘The UTERUS project’ from 2019 to 2021. All tumours underwent IHC staining for the mismatch repair (MMR) proteins and MLH1 promoter methylation testing. MMR proficient tumours and MLH1 methylated tumours underwent a 30 gene germline test, while those tumours that were MMR deficient (dMMR) without MLH1 methylation underwent a paired somatic/germline LS specific panel. Results Of the dMMR tumours with MLH1 deficiency all demonstrated MLH1 promoter methylation. Of the remaining 12 dMMR tumours half were found to have LS and half had double somatic MMR. It was observed that 43% of eligible patients were not enrolled by their caring physician. Of those, 75% were followed by a non-oncologist. Conclusions Paired somatic/germline testing is an appropriate first line test for those tumours that demonstrate dMMR without MLH1 promoter methylation. It was demonstrated that patients with EC being followed by a non-oncologist specialist were less likely to be referred for additional genetic counselling and testing, demonstrating that mainstream genetic resources should also be offered to non-oncologists treating patients with EC.
Jessen et al. (Mon,) studied this question.