Muir–Torre syndrome (MTS), a variant of Lynch syndrome (LS), is identified by the presence of sebaceous carcinomas (SC). A recent retrospective study reveals that MTS/LS is associated with specific pathogenic variants in one of four mismatched repaired (MMR) genes. Therefore, screening SC for MMR could potentially support in the early detection of LS and implementation of preventive interventions. By integrating MMR screening into routine management of SCs, this may enable the identification of patients with Muir–Torre/Lynch syndrome.
Sam Cook, Royal Victoria Infirmary, Newcastle-upon-Tyne, UK, and colleagues emphasised that sebaceous tumours have the highest correlation with all cancers associated with LS, with 18.8–33.3% of patients with sebaceous tumours having LS. They further added that MMR screening of SC samples, which could assist in detecting LS, is not currently a standard practice in England. This lack of screening may result in missed opportunities for LS detection among both SC patients and their families.
The researchers assessed the need of MMR screening for early LS detection by examining the rates of SC cases screened for MMR and MMR deficiencies. The researchers analysed a total of 1,077 SC cases in England, between January 2008–December 2018. Among these cases, 739 were extraocular, and 338 were periocular.
The findings revealed that men had higher age-standardised incidence rates per 1 million person-years compared to women (2.74; 95% confidence interval: 2.52–9.69 versus 1.47; 95% confidence interval: 1.40–1.62). Among the total number of patients, 19% developed at least one malignancy associated with MTS/LS. MMR immunohistochemical screening was conducted in 20% of patients, with an annual increase from 4% in 2008 to 34% in 2018. Patients with tumours showcasing MMR deficiency were younger in age compared to those with MMR-proficient tumours (67 years versus 78 years).
The research team observed higher rates of LS-associated cancers in extraocular SC compared to periocular SC (39% versus 11%). Resultingly, the authors recommended prioritising MMR screening efforts for patients with extraocular SCs, especially when testing resources are limited. Nonetheless, the findings support the recommendation that all patients with SC tumours should be provided with MMR screening.