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Exome sequencing and array-based comparative genomic hybridisation analysis of preferential 6-methylmercaptopurine producers

Chua EW, Cree S, Barclay ML, Doudney K, Lehnert K, Aitchison A, et al.

Pharmacogenomics J, 2015 Oct;15(5):414-21.
PMID: 25752523 DOI: 10.1038/tpj.2015.9

Preferential conversion of azathioprine or 6-mercaptopurine into methylated metabolites is a major cause of thiopurine resistance. To seek potentially Mendelian causes of thiopurine hypermethylation, we recruited 12 individuals who exhibited extreme therapeutic resistance while taking azathioprine or 6-mercaptopurine and performed whole-exome sequencing (WES) and copy-number variant analysis by array-based comparative genomic hybridisation (aCGH). Exome-wide variant filtering highlighted four genes potentially associated with thiopurine metabolism (ENOSF1 and NFS1), transport (SLC17A4) or therapeutic action (RCC2). However, variants of each gene were found only in two or three patients, and it is unclear whether these genes could influence thiopurine hypermethylation. Analysis by aCGH did not identify any unusual or pathogenic copy-number variants. This suggests that if causative mutations for the hypermethylation phenotype exist they may be heterogeneous, occurring in several different genes, or they may lie within regulatory regions not captured by WES. Alternatively, hypermethylation may arise from the involvement of multiple genes with small effects. To test this hypothesis would require recruitment of large patient samples and application of genome-wide association studies.
Teledentistry may help in detecting oral cancers in current GP and dentist shortages

Bradley P, Deane J, O'Hara J, Kennedy M, Carrard VC, Cheong SC, et al.

BMJ, 2024 Mar 01;384:q512.
PMID: 38428988 DOI: 10.1136/bmj.q512
Clinicopathological features of squamous cell carcinoma of the oral cavity and oropharynx in young patients

Martinez RC, Sathasivam HP, Cosway B, Paleri V, Fellows S, Adams J, et al.

Br J Oral Maxillofac Surg, 2018 May;56(4):332-337.
PMID: 29628167 DOI: 10.1016/j.bjoms.2018.03.011

Our aim was to examine the clinicopathological features of squamous cell carcinoma (SCC) of the oral cavity and oropharynx in a group of young patients who were dignosed during a 15-year period (2000-2014). Patients' clinical details, risk factors, and survival were obtained from medical records. Formalin-fixed, paraffin-embedded, tissue was tested for high-risk human papillomavirus (HPV). The results were compared with those of a matching group of older patients. We identified 91 patients who were younger than 45 years old, and the 50 youngest patients were studied in detail. The male:female ratio was 2:1, with more tumours located in the oral cavity than in the oropharynx (35 compared with 15). HPV-related SCC was restricted to the oropharynx. When matched for site, stage and HPV status, five-year overall survival was similar in young and matched older patients (log-rank test, p=0.515). Our findings suggest that young patients with oral SCC have a disease profile similar to that of older patients with the condition. It is plausible that prognostic information generally available for oral cancers is applicable to young patients with the disease.
Changes in Epidermal Growth Factor Receptor Gene Copy Number during Oral Carcinogenesis

Bates T, Kennedy M, Diajil A, Goodson M, Thomson P, Doran E, et al.

Cancer Epidemiol Biomarkers Prev, 2016 Jun;25(6):927-35.
PMID: 27197272 DOI: 10.1158/1055-9965.EPI-15-0949

BACKGROUND: Oral squamous cell carcinoma (OSCC) is a global healthcare problem associated with poor clinical outcomes. Early detection is key to improving patient survival. OSCC may be preceded by clinically recognizable lesions, termed oral potentially malignant disorders (OPMD). As histologic assessment of OPMD does not accurately predict their clinical behavior, biomarkers are required to detect cases at risk of malignant transformation. Epidermal growth factor receptor gene copy number (EGFR GCN) is a validated biomarker in lung non-small cell carcinoma. We examined EGFR GCN in OPMD and OSCC to determine its potential as a biomarker in oral carcinogenesis.
METHODS: EGFR GCN was examined by in situ hybridization (ISH) in biopsies from 78 patients with OPMD and 92 patients with early-stage (stages I and II) OSCC. EGFR ISH signals were scored by two pathologists and a category assigned by consensus. The data were correlated with patient demographics and clinical outcomes.
RESULTS: OPMD with abnormal EGFR GCN were more likely to undergo malignant transformation than diploid cases. EGFR genomic gain was detected in a quarter of early-stage OSCC, but did not correlate with clinical outcomes.
CONCLUSION: These data suggest that abnormal EGFR GCN has clinical utility as a biomarker for the detection of OPMD destined to undergo malignant transformation. Prospective studies are required to verify this finding. It remains to be determined if EGFR GCN could be used to select patients for EGFR-targeted therapies.
IMPACT: Abnormal EGFR GCN is a potential biomarker for identifying OPMD that are at risk of malignant transformation. Cancer Epidemiol Biomarkers Prev; 25(6); 927-35. ©2016 AACR.
Fulltext Association of type and location of BRCA1 and BRCA2 mutations with risk of breast and ovarian cancer

Rebbeck TR, Mitra N, Wan F, Sinilnikova OM, Healey S, McGuffog L, et al.

JAMA, 2015 Apr 07;313(13):1347-61.
PMID: 25849179 DOI: 10.1001/jama.2014.5985

IMPORTANCE: Limited information about the relationship between specific mutations in BRCA1 or BRCA2 (BRCA1/2) and cancer risk exists.
OBJECTIVE: To identify mutation-specific cancer risks for carriers of BRCA1/2.
DESIGN, SETTING, AND PARTICIPANTS: Observational study of women who were ascertained between 1937 and 2011 (median, 1999) and found to carry disease-associated BRCA1 or BRCA2 mutations. The international sample comprised 19,581 carriers of BRCA1 mutations and 11,900 carriers of BRCA2 mutations from 55 centers in 33 countries on 6 continents. We estimated hazard ratios for breast and ovarian cancer based on mutation type, function, and nucleotide position. We also estimated RHR, the ratio of breast vs ovarian cancer hazard ratios. A value of RHR greater than 1 indicated elevated breast cancer risk; a value of RHR less than 1 indicated elevated ovarian cancer risk.
EXPOSURES: Mutations of BRCA1 or BRCA2.
MAIN OUTCOMES AND MEASURES: Breast and ovarian cancer risks.
RESULTS: Among BRCA1 mutation carriers, 9052 women (46%) were diagnosed with breast cancer, 2317 (12%) with ovarian cancer, 1041 (5%) with breast and ovarian cancer, and 7171 (37%) without cancer. Among BRCA2 mutation carriers, 6180 women (52%) were diagnosed with breast cancer, 682 (6%) with ovarian cancer, 272 (2%) with breast and ovarian cancer, and 4766 (40%) without cancer. In BRCA1, we identified 3 breast cancer cluster regions (BCCRs) located at c.179 to c.505 (BCCR1; RHR = 1.46; 95% CI, 1.22-1.74; P = 2 × 10(-6)), c.4328 to c.4945 (BCCR2; RHR = 1.34; 95% CI, 1.01-1.78; P = .04), and c. 5261 to c.5563 (BCCR2', RHR = 1.38; 95% CI, 1.22-1.55; P = 6 × 10(-9)). We also identified an ovarian cancer cluster region (OCCR) from c.1380 to c.4062 (approximately exon 11) with RHR = 0.62 (95% CI, 0.56-0.70; P = 9 × 10(-17)). In BRCA2, we observed multiple BCCRs spanning c.1 to c.596 (BCCR1; RHR = 1.71; 95% CI, 1.06-2.78; P = .03), c.772 to c.1806 (BCCR1'; RHR = 1.63; 95% CI, 1.10-2.40; P = .01), and c.7394 to c.8904 (BCCR2; RHR = 2.31; 95% CI, 1.69-3.16; P = .00002). We also identified 3 OCCRs: the first (OCCR1) spanned c.3249 to c.5681 that was adjacent to c.5946delT (6174delT; RHR = 0.51; 95% CI, 0.44-0.60; P = 6 × 10(-17)). The second OCCR spanned c.6645 to c.7471 (OCCR2; RHR = 0.57; 95% CI, 0.41-0.80; P = .001). Mutations conferring nonsense-mediated decay were associated with differential breast or ovarian cancer risks and an earlier age of breast cancer diagnosis for both BRCA1 and BRCA2 mutation carriers.
CONCLUSIONS AND RELEVANCE: Breast and ovarian cancer risks varied by type and location of BRCA1/2 mutations. With appropriate validation, these data may have implications for risk assessment and cancer prevention decision making for carriers of BRCA1 and BRCA2 mutations.