STROGAR – STrengthening the Reporting Of Genetic Association studies in Radiogenomics

AbstractDespite publication of numerous radiogenomics studies to date, positive single nucleotide polymorphism (SNP) associations have rarely been reproduced in independent validation studies. A major reason for these inconsistencies is a high number of false positive findings because no adjustments were made for multiple comparisons. It is also possible that some validation studies were false negatives due to methodological shortcomings or a failure to reproduce relevant details of the original study. Transparent reporting is needed to ensure these flaws do not hamper progress in radiogenomics. In response to the need for improving the quality of research in the area, the Radiogenomics Consortium produced an 18-item checklist for reporting radiogenomics studies. It is recognised that not all studies will have recorded all of the information included in the checklist. However, authors should report on all checklist items and acknowledge any missing information. Use of STROGAR guidelines will advance the field of radiogenomics by increasing the transparency and completeness of reporting

Development and Validation of a 28-gene Hypoxia-related Prognostic Signature for Localized Prostate Cancer.

BACKGROUND: Hypoxia is associated with a poor prognosis in prostate cancer. This work aimed to derive and validate a hypoxia-related mRNA signature for localized prostate cancer. METHOD: Hypoxia genes were identified in vitro via RNA-sequencing and combined with in vivo gene co-expression analysis to generate a signature. The signature was independently validated in eleven prostate cancer cohorts and a bladder cancer phase III randomized trial of radiotherapy alone or with carbogen and nicotinamide (CON). RESULTS: A 28-gene signature was derived. Patients with high signature scores had poorer biochemical recurrence free survivals in six of eight independent cohorts of prostatectomy-treated patients (Log rank test P \u3c .05), with borderline significances achieved in the other two (P \u3c .1). The signature also predicted biochemical recurrence in patients receiving post-prostatectomy radiotherapy (n = 130, P = .007) or definitive radiotherapy alone (n = 248, P = .035). Lastly, the signature predicted metastasis events in a pooled cohort (n = 631, P = .002). Prognostic significance remained after adjusting for clinic-pathological factors and commercially available prognostic signatures. The signature predicted benefit from hypoxia-modifying therapy in bladder cancer patients (intervention-by-signature interaction test P = .0026), where carbogen and nicotinamide was associated with improved survival only in hypoxic tumours. CONCLUSION: A 28-gene hypoxia signature has strong and independent prognostic value for prostate cancer patients

Meta-GWAS identifies the heritability of acute radiation-induced toxicities in head and neck cancer

Background and purpose: We aimed to the genetic components and susceptibility variants associated with acute radiation-induced toxicities (RITs) in patients with head and neck cancer (HNC). Materials and methods: We performed the largest meta-GWAS of seven European cohorts (n = 4,042). Patients were scored weekly during radiotherapy for acute RITs including dysphagia, mucositis, and xerostomia. We analyzed the effect of variants on the average burden (measured as area under curve, AUC) per each RIT, and standardized total average acute toxicity (STATacute) score using a multivariate linear regression. We tested suggestive variants (p < 1.0x10-5) in discovery set (three cohorts; n = 2,640) in a replication set (four cohorts; n = 1,402). We meta-analysed all cohorts to calculate RITs specific SNP-based heritability, and effect of polygenic risk scores (PRSs), and genetic correlations among RITS. Results: From 393 suggestive SNPs identified in discovery set; 37 were nominally significant (preplication < 0.05) in replication set, but none reached genome-wide significance (pcombined < 5 × 10-8). In-silico functional analyses identified “3′-5'-exoribonuclease activity” (FDR = 1.6e-10) for dysphagia, “inositol phosphate-mediated signalling” for mucositis (FDR = 2.20e-09), and “drug catabolic process” for STATacute (FDR = 3.57e-12) as the most enriched pathways by the RIT specific suggestive genes. The SNP-based heritability (±standard error) was 29 ± 0.08 % for dysphagia, 9 ± 0.12 % (mucositis) and 27 ± 0.09 % (STATacute). Positive genetic correlation was rg = 0.65 (p = 0.048) between dysphagia and STATacute. PRSs explained limited variation of dysphagia (3 %), mucositis (2.5 %), and STATacute (0.4 %). Conclusion: In HNC patients, acute RITs are modestly heritable, sharing 10 % genetic susceptibility, when PRS explains < 3 % of their variance. We identified numerus suggestive SNPs, which remain to be replicated in larger studies

REQUITE: A prospective multicentre cohort study of patients undergoing radiotherapy for breast, lung or prostate cancer

Purpose: REQUITE aimed to establish a resource for multi-national validation of models and biomarkers that predict risk of late toxicity following radiotherapy. The purpose of this article is to provide summary descriptive data. Methods: An international, prospective cohort study recruited cancer patients in 26 hospitals in eight countries between April 2014 and March 2017. Target recruitment was 5300 patients. Eligible patients had breast, prostate or lung cancer and planned potentially curable radiotherapy. Radiotherapy was prescribed according to local regimens, but centres used standardised data collection forms. Pre-treatment blood samples were collected. Patients were followed for a minimum of 12 (lung) or 24 (breast/prostate) months and summary descriptive statistics were generated. Results: The study recruited 2069 breast (99% of target), 1808 prostate (86%) and 561 lung (51%) cancer patients. The centralised, accessible database includes: physician-(47,025 forms) and patient-(54,901) reported outcomes; 11,563 breast photos; 17,107 DICOMs and 12,684 DVHs. Imputed genotype data are available for 4223 patients with European ancestry (1948 breast, 1728 prostate, 547 lung). Radiation-induced lymphocyte apoptosis (RILA) assay data are available for 1319 patients. DNA (n = 4409) and PAXgene tubes (n = 3039) are stored in the centralised biobank. Example prevalences of 2-year (1-year for lung) grade >= 2 CTCAE toxicities are 13% atrophy (breast), 3% rectal bleeding (prostate) and 27% dyspnoea (lung). Conclusion: The comprehensive centralised database and linked biobank is a valuable resource for the radiotherapy community for validating predictive models and biomarkers. Patient summary: Up to half of cancer patients undergo radiation therapy and irradiation of surrounding healthy tissue is unavoidable. Damage to healthy tissue can affect short-and long-term quality-of-life. Not all patients are equally sensitive to radiation "damage" but it is not possible at the moment to identify those who are. REQUITE was established with the aim of trying to understand more about how we could predict radiation sensitivity. The purpose of this paper is to provide an overview and summary of the data and material available. In the REQUITE study 4400 breast, prostate and lung cancer patients filled out questionnaires and donated blood. A large amount of data was collected in the same way. With all these data and samples a database and biobank were created that showed it is possible to collect this kind of information in a standardised way across countries. In the future, our database and linked biobank will be a resource for research and validation of clinical predictors and models of radiation sensitivity. REQUITE will also enable a better understanding of how many people suffer with radiotherapy toxicity

Polygenic hazard score is associated with prostate cancer in multi-ethnic populations

Genetic models for cancer have been evaluated using almost exclusively European data, which could exacerbate health disparities. A polygenic hazard score (PHS1) is associated with age at prostate cancer diagnosis and improves screening accuracy in Europeans. Here, we evaluate performance of PHS2 (PHS1, adapted for OncoArray) in a multi-ethnic dataset of 80,491 men (49,916 cases, 30,575 controls). PHS2 is associated with age at diagnosis of any and aggressive (Gleason score >= 7, stage T3-T4, PSA >= 10ng/mL, or nodal/distant metastasis) cancer and prostate-cancer-specific death. Associations with cancer are significant within European (n=71,856), Asian (n=2,382), and African (n=6,253) genetic ancestries (p<10(-180)). Comparing the 80(th)/20(th) PHS2 percentiles, hazard ratios for prostate cancer, aggressive cancer, and prostate-cancer-specific death are 5.32, 5.88, and 5.68, respectively. Within European, Asian, and African ancestries, hazard ratios for prostate cancer are: 5.54, 4.49, and 2.54, respectively. PHS2 risk-stratifies men for any, aggressive, and fatal prostate cancer in a multi-ethnic dataset. A polygenic hazard score (PHS1) improves prostate cancer screening accuracy in European patients. Here, the authors test the performance of a version compatible with OncoArray genotypes (PHS2) in a multi-ethnic dataset and find that it risk-stratifies men for any, aggressive, and fatal prostate cancer

Hypoxia-regulated glucose transporter Glut-1 may influence chemosensitivity to some alkylating agents: results of EORTC (First Translational Award) study of the relevance of tumour hypoxia to the outcome of chemotherapy in human tumour-derived xenografts.

Tumour hypoxia confers poor prognosis in a wide range of solid tumours, due to an increased malignancy, increased likelihood of metastasis and treatment resistance. Poorly oxygenated tumours are resistant to both radiation therapy and chemotherapy. However, although the link between radiation therapy and hypoxia is well established in a range of clinical studies, evidence of its influence on chemotherapy response is lacking. In this study, a panel of human tumour-derived xenografts that have been characterised previously for in vivo response to a large series of anti-cancer agents, and have been found to show chemosensitivities that correlate strongly with the parent tumour, were used to address this issue. Immunohistochemistry was carried out on formalin-fixed, paraffin-embedded sections of xenograft samples to detect expression of the intrinsic hypoxia marker Glut-1 and adducts of the bioreductive hypoxia marker pimonidazole. Glut-1 scores correlated significantly with T/C values for CCNU sensitivity (r = 0.439, P = 0.036, n = 23) and showed a borderline significant correlation with dacarbazine T/C (r = 0.405, P = 0.076, n = 20). However, there was no correlation between both Glut-1 and pimonidazole scores and T/C obtained for the bioreductive drug mitomycin C. The use of human tumour-derived xenografts offers a potentially useful way of using archival material to determine the influence of hypoxia and other tumour-microenvironmental factors on chemosensitivity without the direct use of human subjects

Glucose transporter Glut-1 expression correlates with tumor hypoxia and predicts metastasis-free survival in advanced carcinoma of the cervix

Hypoxic tumors are known to be more malignant, to be more likely to metastasize, and to have a poor prognosis. They are also radio- and chemoresistant. For this reason, it is desirable that a clinically useful marker of hypoxia is found, so that treatment with radiotherapy and bioreductive chemotherapy can be rationally applied to individual patients. Glut-1 is a facilitative glucose transporter that is ubiquitously expressed in normal tissue and expressed at higher levels in a number of tumors. Its potential as an intrinsic hypoxia marker arises from its dual control in hypoxic conditions by reduced oxidative phosphorylation and the hypoxia-inducible factor (HIF-1) oxygen-sensing pathway. Eppendorf histography, by virtue of its proven predictive qualities, is a suitable gold standard used in our laboratory to validate new hypoxia markers. Using this technique, pretreatment pO2 measurements were performed on 54 patients with locally advanced cervical carcinoma. Then, immunohistochemical staining was used to detect Glut-1 protein in individual tumor biopsy sections. Both measurements were made before initiation of treatment. By using a low-tech scoring system, pO2 was found to correlate weakly with Glut-1 score (r = 0.28; P = 0.04). To extrapolate this correlation to the known adverse effects of tumor hypoxia on outcome, we examined the prognostic significance of Glut-1 staining in a retrospective series of 121 patients. An absence of Glut-1 significantly increased the likelihood of metastasis-free survival (P = 0.022) but did not significantly effect disease-free or recurrence-free survival. These findings suggest that Glut-1 be an intrinsic marker of hypoxia that can easily be applied in a clinical setting

No relationship between 18F-fluorodeoxyglucose positron emission tomography and expression of Glut-1 and -3 and hexokinase I and II in high-grade glioma

The purpose of this study was to compare glucose metabolism, measured using 18F-fluorodeoxyglucose positron emission tomography ([18F]FDG-PET), with the expression of Glut-1 and -3 and hexokinase I (Hex I) and II in high-grade glioma. The retrospective study involved 27 patients with WHO classification grade III and IV glioma, with either newly diagnosed or recurrent tumours. Patients underwent dynamic and static [18F]FDG-PET to glucose metabolic rate (MRGlu) and standardised uptake value (SUV), respectively. Tumour biopsies were obtained and stained using immunohistochemistry for the expression of Glut-1, -3, Hex I and II. Relationships between variables were studied using Spearman's rank correlation test. Results showed that the expression of Glut-1, Glut-3, Hex I and Hex II varied between and within the tumour samples. The mean of MRGlu was 0.2 (range 0.09-0.25) µmol/min/ml and that of SUV was 4.2 (range 3.2-5.2). There were no significant relationships among the tumour expression of any of the proteins studied with either MRGlu or SUV (p>0.21 for all). In conclusion, the lack of relationship between the immunohistochemical expression of Glut-1, -3, Hex I or II and glucose metabolism measured using [18F]FDG-PET in patients with high-grade glioma may be due to the tissue heterogeneity and presence of necrosis in high-grade tumours