Background Women with epithelial ovarian cancer (OC) have a higher chance to benefit from poly (ADP-ribose) polymerase inhibitor (PARPi) therapy if their tumor has a somatic or hereditary BRCA1/2 pathogenic variant. Current guidelines advise BRCA1/2 genetic predisposition testing for all OC patients, though this does not detect somatic variants. We assessed the feasibility of a workflow for universal tumor DNA BRCA1/2 testing of all newly diagnosed OC patients as a prescreen for PARPi treatment and cancer predisposition testing. Methods Formalin-fixed paraffin-embedded tissue was obtained from OC patients in seven hospitals immediately after diagnosis or primary surgery. DNA was extracted, and universal tumor BRCA1/2 testing was then performed in a single site. Diagnostic yield, uptake, referral rates for genetic predisposition testing, and experiences of patients and gynecologists were evaluated. Results Tumor BRCA1/2 testing was performed for 315 (77.6%) of the 406 eligible OC samples, of which 305 (96.8%) were successful. In 51 of these patients, pathogenic variants were detected (16.7%). Most patients (88.2%) went on to have a genetic predisposition test. BRCA1/2 pathogenic variants were shown to be hereditary in 56.8% and somatic in 43.2% of patients. Participating gynecologists and patients were overwhelmingly positive about the workflow. Conclusions Universal tumor BRCA1/2 testing in all newly diagnosed OC patients is feasible, effective, and appreciated by patients and gynecologists. Because many variants cannot be detected in DNA from blood, testing tumor DNA as the first step can double the identification rate of patients who stand to benefit most from PARP inhibitors.

We examined the validity of immunohistochemistry for mismatch repair (MMR) proteins in colorectal cancer specimens to identify patients at risk for Lynch syndrome (hereditary nonpolyposis colorectal cancer) and patients with sporadic microsatellite instable colorectal cancer. This was assessed by observer agreement for and accuracy of interpretation of immunohistochemistry. Seven pathologists from 5 different pathology laboratories evaluated 100 molecularly defined colorectal cancers stained for MLH1, PMS2, MSH2, and MSH6. Two of the pathologists were experienced in interpretation of immunohistochemistry for MMR proteins. After evaluation of a subset of 20 cases, a discussion meeting was organized, after which pathologists evaluated all 100 cases. Staining patterns were interpreted as aberrant, normal, or indefinite. In 82% of tumors, 5 or more pathologists reached the same interpretation, which was considered the consensus diagnosis. Consensus was reached slightly less frequently in microsatellite instable than in stable tumors, and interobserver variation was moderate to substantial (kappa: 0.49-0.79). More microsatellite instable tumors showed an indefinite staining pattern compared with microsatellite stable tumors. Three out of 7 pathologists, including the 2 experienced pathologists, did not miss a microsatellite instable tumor. Each pathologist found at least 1 tumor with an aberrant staining pattern, whereas consensus was a normal staining pattern and the tumor was microsatellite stable. We conclude that, if restricted to experienced pathologists, immunohistochemistry is a valid tool to identify patients at risk for Lynch syndrome and patients with sporadic microsatellite instable colorectal cancer. An indefinite or aberrant staining result has to be followed by molecular microsatellite instability analysis to confirm the presence of a defective DNA MMR system.

The cancer risk is unknown for those families in which a microsatellite instable tumour is neither explained by MLH1 promoter methylation nor by a germline mutation in a mismatch repair (MMR) gene. Such information is essential for genetic counselling. Families suspected of Lynch syndrome (n ¼ 614) were analysed for microsatellite instability, MLH1 promoter methylation and/or germline mutations in MLH1, MSH2, MSH6, and PMS2. Characteristics of the 76 families with a germline mutation (24 MLH1, 2 PMS2, 32 MSH2, and 18 MSH6) were compared with those of 18 families with an unexplained microsatellite instable tumour. The mean age at diagnosis of the index patients in both groups was comparable at 44 years. Immunohistochemistry confirmed the loss of an MMR protein. Together this suggests germline inactivation of a known gene. The Amsterdam II criteria were fulfilled in 50/75 families (66%) that carried a germline mutation in an MMR gene and in only 2/18 families (11%) with an unexplained microsatellite instable tumour (Po0.0001). Current diagnostic strategies can detect almost all highly penetrant MMR gene mutations. Patients with an as yet unexplained microsatellite instable tumour likely carry a different type of mutation that confers a lower risk of cancer for relatives.

Tumor angiogenesis, a major requirement for tumor outgrowth and metastasis formation, is regulated by pro-and anti-angiogenic factors. We have studied the expression of a panel of angiogenic factors, and of the angiogenesis inhibitor angiostatin, in a panel of human melanoma cell lines giving rise to xenografts with different vascular densities. Angiogenic-factor expression was analyzed in vitro (cell lines) and in vivo (xenografts), both at mRNA (RT-PCR and Northern blot) and at protein level (ELISA and Western blot). In vitro angiostatin generation was assessed by Western-blot analysis. Expression of bFGF and VEGF was clearly correlated with a high degree of vascularization, confirming the importance of these factors for tumor angiogenesis. In addition, there was exclusive or elevated in vitro expression of angiogenic factors IL-8, PDGF-AB, and, to a lesser extent, midkine in cell lines that formed highly vascularized tumors. A similar angiogenic-factor-expression pattern was found in the corresponding xenografts, with the exception of VEGF. In most cell lines, this factor had low expression in vitro which was strongly enhanced in vivo. Although all 8 melanoma cell lines were able to excise the angiostatin fragment from the plasminogen parent molecule in vitro, cell lines BLM and M14 showed the most potent angiostatin generation. In vitro angiostatin generation by cell lysates prepared from melanoma xenografts was comparable in all xenograft types. Thus, in our model system we found no correlation between angiostatin generation and vascular density. Our study has limited the number of pro-angiogenic factors that may be involved in melanoma angiogenesis, and provides evidence for the notion that regulation of tumor angiogenesis is dependent on multiple factors. Inhibition of angiogenesis for therapeutic purposes, therefore, should preferably not concentrate on a single factor. Int.

Universal mismatch repair deficiency (dMMR) testing of colorectal cancer (CRC) is promoted as routine diagnostics to prescreen for Lynch syndrome. We evaluated the yield and experience of age‐related molecular investigation for heritable and nonheritable causes of dMMR in CRC below age 70 to identify Lynch Syndrome. In a prospective cohort of 3602 newly diagnosed CRCs below age 70 from 19 hospitals, dMMR, MLH1 promoter hypermethylation, germline MMR gene and somatic MMR gene testing was assessed in daily practice. Yield was evaluated using data from the Dutch Pathology Registry (PALGA) and two regional genetic centers. Experiences of clinicians were evaluated through questionnaires. Participating clinicians were overwhelmingly positive about the clinical workflow. Pathologists routinely applied dMMR‐testing in 84% CRCs and determined 10% was dMMR, largely due to somatic MLH1 hypermethylation (66%). Of those, 69% with dMMR CRC below age 70 without hypermethylation were referred for genetic testing, of which 55% was due to Lynch syndrome (hereditary) and 43% to somatic biallelic pathogenic MMR (nonhereditary). The prevalence of Lynch syndrome was 18% in CRC < 40, 1.7% in CRC age 40‐64 and 0.7% in CRC age 65‐69. Age 65‐69 represents most cases with dMMR, in which dMMR due to somatic causes (13%) is 20 times more prevalent than Lynch syndrome. In conclusion, up to age 65 routine diagnostics of (non‐)heritable causes of dMMR CRCs effectively identifies Lynch syndrome and reduces Lynch‐like diagnoses. Above age 64, the effort to detect one Lynch syndrome patient in dMMR CRC is high and germline testing rarely needed.