Impact of universal immunohistochemistry on Lynch syndrome diagnosis in an Australian colorectal cancer cohort.

BACKGROUND: Current guidelines recommend a step-wise screening algorithm for all colorectal carcinomas (CRC) to identify patients with Lynch syndrome (LS). AIM: To describe the frequencies of mismatch repair deficiency (dMMR), BRAFV600E mutations and MLH1 methylation in resected CRC, and evaluate the impact of universal screening on LS detection. METHODS: Retrospectively, 1171 consecutive cases of resected CRC were identified between 2010 and 2017 from a large multi-centre pathology service. Testing for dMMR by immunohistochemistry (IHC) was initiated by the reporting pathologist from 2010, until universal testing was introduced in 2015. Patients with dMMR were referred to the Family Cancer Clinic (FCC) for consideration of germline mutation analysis. RESULTS: IHC was performed on 680 tumours, with abnormal expression in 124 (18%). Referral to FCC was made for 44 of the 88 patients with abnormal IHC (excluding those with BRAFV600E mutations). Of the 29 who attended, 16 underwent germline genetic testing, and LS was diagnosed in 7 with a germline mutation. After implementation of universal testing, there was a greater incidence of dMMR (17% vs 10%, P = 0.02), rate of BRAFV600E testing (79% vs 25%, P < 0.0001), and referral to FCC (61% vs 33%, P < 0.0001), but no difference in FCC attendance rate (65% vs 67%, P = 0.59) or new LS diagnoses (1.6% vs 0%, P = 0.06). CONCLUSION: Universal IHC testing may increase the detection of LS, and should be implemented where possible. However, the full benefit was limited by low referral to and uptake of genetic testing, and further strategies are needed to overcome these barriers.

Utility of immunohistochemistry for mismatch repair proteins on colorectal polyps in the familial cancer clinic.

BACKGROUND: Immunohistochemistry for loss of expression of one or more of the mismatch repair proteins is performed on colorectal cancer tissue as a screening test for Lynch syndrome; however, its role in pre-malignant polyps remains controversial. AIM: To determine the effectiveness of mismatch repair immunohistochemistry performed on pre-malignant colorectal polyps in identifying Lynch syndrome, focusing on clinical utility and value. METHODS: A retrospective audit was conducted of mismatch repair immunohistochemistry performed on non-malignant polyps in patients who attended the Family Cancer Clinic at the Royal Melbourne Hospital. Two hundred and six patient records over a 10-year period (2006-2016) were reviewed. Personal and family history data were collected, including genetic testing results. RESULTS: Of the 57 patients who underwent polyp testing, the family histories comprised Amsterdam II Criteria (12.3%), Lynch syndrome-associated malignancies (42.1%), Lynch syndrome-associated malignancies and polyps (35.1%) and polyps only (8.8%); 10.5% of patients had no significant family history. Normal expression of the mismatch repair proteins was observed in 94.7% of patients; loss of expression was observed in three individuals with concordant germline variants in two patients (one PMS2 variant of unknown significance and one MSH6 mutation). Additional genetic testing in 21 patients with normal immunohistochemistry did not identify any additional Lynch syndrome cases. CONCLUSION: The clinical utility of mismatch repair immunohistochemistry on polyp tissue was low. No additional cases of Lynch syndrome were identified, and a large proportion of patients proceeded to germline testing despite normal polyp immunohistochemistry. We suggest there is no value in this approach.

Mainstreaming cancer genetics: A model integrating germline BRCA testing into routine ovarian cancer clinics.

OBJECTIVE: Owing to the rapid increase in clinical need, we aimed to implement and review the performance of a mainstreaming model of germline BRCA1/2 genetic testing in eligible women with high grade non-mucinous epithelial ovarian cancer via a Genetic Counselor embedded in the gynecology oncology clinic. METHODS: The model implemented involved a specialized referral form, weekly genetics-lead multidisciplinary review of referrals, and pre- and post-test genetic counseling provided by an embedded genetic counselor during chemotherapy chair time. Performance and outcomes were retrospectively audited over the following two consecutive one year periods, including survey data on medical specialist comfort with mainstreaming and the model. RESULTS: Sixty-four women underwent mainstreamed BRCA1/2 testing over the two year post-implementation period with a rate of detection of BRCA1/2 pathogenic variants of 17%. The referral rate for eligible women significantly increased to over 90% (p<0.001). The median time from referral to delivery of genetic testing results was less than five months, with >90% of patients receiving results during first line chemotherapy. Genetic counseling time decreased from 120 to 54min. Cancer specialists were comfortable with the model. CONCLUSIONS: The mainstreaming model proved effective, increasing uptake of genetic testing in eligible patients to over 90%; it was efficient for patients, genetic counselors and cancer specialists and acceptable to cancer specialists. It facilitated co-location of genetic and oncology service delivery but separation of clinical responsibility for genetic testing to a specialist genetics service, ensuring accurate and robust patient-centred care.

Renal angiomyolipoma in Birt-Hogg-Dube syndrome: A case study supporting overlap with tuberous sclerosis complex.

Birt-Hogg-Dube syndrome (BHD) is an autosomal dominant disease characterised by benign cutaneous lesions, pulmonary cysts, and an increased risk of renal tumors. This rare condition is due to a mutation in the folliculin (FLCN) gene on chromosome 17q11.2, which has a role in the mechanistic/mammalian target of rapamycin (mTOR) signaling pathway of tumorigenesis. This case illustrates a patient with BHD and a renal angiomyolipoma, a neoplastic lesion not usually associated with BHD but common in Tuberous Sclerosis Complex (TSC). There is both clinical and molecular overlap between BHD and TSC, which may arise from similarities in function of the TSC and FLCN proteins in the mTOR pathway; this case further demonstrates this potential correlation. © 2016 Wiley Periodicals, Inc.

Cancer Diagnoses Following Abnormal Noninvasive Prenatal Testing: A Case Series, Literature Review, and Proposed Management Model.

Noninvasive prenatal testing (NIPT) is a screening test for fetal chromosomal aneuploidy using cell-free DNA derived from maternal blood. It has been rapidly accepted into obstetric practice because of its application from 10-weeks' gestation, and its high sensitivity and specificity. NIPT results can be influenced by several factors including placental or maternal mosaicism and co-twin demise; cell-free DNA from a maternal origin can also complicate interpretation, with evidence that NIPT can detect previously unsuspected malignancies. This study aimed to develop management guidelines for women with NIPT results suspicious of maternal malignancy. The Peter MacCallum Cancer Center's experience of seven cases where abnormal NIPT results led to investigation for maternal malignancy between 2016 and 2019 were reviewed, along with the published literature. Six of the seven women (86%) referred for investigation were diagnosed with advanced malignancies, including colorectal cancer, breast cancer, melanoma, and Hodgkin lymphoma. Based on our single-center experience, as well as the available literature, guidelines for the investigation of women with NIPT results suspicious of malignancy are proposed, including utilization of fluorodeoxyglucose positron emission tomography-computed tomography, which had a high concordance with other investigations and diagnoses. These guidelines include maternal and fetal investigations, as well as consideration of the complex medical, psychologic, social, and ethical needs of these patients and their families.

Hemangioblastoma in Hereditary Leiomyomatosis and Renal Cell Cancer Syndrome: a phenotypic overlap between VHL and HLRCC Syndromes.

Hemangioblastomas are rare vascularized central nervous system tumors, which can occur sporadically or be associated with von Hippel Lindau Syndrome. The pathogenesis of hemangioblastomas in von Hippel Lindau Syndrome is proposed to involve a pseudohypoxic intracellular state induced by dysregulation of hypoxia inducible factor alpha due to the absence of von Hippel Lindau protein complex mediated destruction. Dysregulation of fumarate hydratase, a tricarboxylic acid cycle enzyme, occurs in Hereditary Leiomyomatosis and Renal Cell Cancer Syndrome due to germline fumarate hydratase gene mutations, and also results in oncogenesis via hypoxia inducible factor alpha dysregulation. We present a case study of hemangioblastoma occurrence in a Hereditary Leiomyomatosis and Renal Cell Cancer Syndrome patient and propose it as possible evidence of a phenotypic overlap between von Hippel Lindau and Hereditary Leiomyomatosis and Renal Cell Cancer Syndromes due to their overlapping role in the biochemical regulation of hypoxia inducible factor alpha.

Update on Hereditary Colorectal Cancer: Improving the Clinical Utility of Multigene Panel Testing.

Colorectal cancer (CRC), one of the most common cancers, is a major public health issue globally, especially in Westernized countries. Up to 35% of CRCs are thought to be due to heritable factors, but currently only 5% to 10% of CRCs are attributable to high-risk mutations in known CRC susceptibility genes, predominantly the mismatch repair genes (Lynch syndrome) and adenomatous polyposis coli gene (APC; familial adenomatous polyposis). In this era of precision medicine, high-risk mutation carriers, when identified, can be offered various risk management options that prevent cancers and improve survival, including risk-reducing medication, screening for early detection, and surgery. The practice of clinical genetics is currently transitioning from phenotype-directed single gene testing to multigene panels, now offered by numerous providers. For CRC, the genes included across these panels vary, ranging from well established, clinically actionable susceptibility genes with quantified magnitude of risk, to genes that lack extensive validation or have less evidence of association with CRC and, therefore, have minimal clinical utility. The current lack of consensus regarding inclusion of genes in CRC panels presents challenges in patient counseling and management, particularly when a variant in a less validated gene is identified. Furthermore, there remain considerable challenges regarding variant interpretation even for the well established CRC susceptibility genes. Ironically though, only through more widespread testing and the accumulation of large international data sets will sufficient information be generated to (i) enable well powered studies to determine if a gene is associated with CRC susceptibility, (ii) to develop better models for variant interpretation and (iii) to facilitate clinical translation.