Christian Ruf

Changes in epidemiologic features of testicular germ cell cancer: Age at diagnosis and relative frequency of seminoma are constantly and significantly increasing

OBJECTIVES Testicular germ cell tumors (GCTs) have their incidence peak in the third and fourth decades of life. Histologically, GCTs comprise of seminoma and nonseminoma at almost equal proportions with a slight preponderance of nonseminoma in most of the major series. Since decades, there is a shift toward decreasing age at presentation. Recently, there are suggestions of a reversal of the age trend, and also, the histologic subtype ratio appears to shift toward seminoma. We retrospectively looked to our patient populations to verify these recent trends. METHODS A total of 2,482 patients with histologically proven GCT diagnosed between 1976 and 2010 were retrospectively evaluated regarding the year of diagnosis, histology of primary tumor, and age at presentation. Patients were categorized according to the following time periods of treatment: before 1990, 1990 to 1994, 1995 to 1999, 2000 to 2004, and 2005 to 2010. Mean age and relative proportion of seminoma were compared among patient categories by employing the chi-square test and analysis of variance, respectively. RESULTS The mean age significantly increased from 28 to 36 years. The age difference between the 2 histologic subtypes remained constant between 6 and 8 years during the entire observation period. The relative proportion of seminoma continuously increased from 30.9% to 56% (P <0.001). CONCLUSION There is evidence of a significant shift toward older age at diagnosis of GCT. In addition, the proportion of seminoma is constantly increasing at the expense of nonseminoma. The reasons for these developments are obscure. However, 2 old theories regarding the pathogenesis of GCT may receive support from our results: first, the theory of divergent pathogenetic pathways of seminoma and nonseminoma and second, the involvement of postnatal environmental factors in the pathogenesis of GCTs.

Micro-RNA expression in cisplatin resistant germ cell tumor cell lines

BackgroundWe compared microRNA expression patterns in three cisplatin resistant sublines derived from paternal cisplatin sensitive germ cell tumor cell lines in order to improve our understanding of the mechanisms of cisplatin resistance.MethodsThree cisplatin resistant sublines (NTERA-2-R, NCCIT-R, 2102EP-R) showing 2.7-11.3-fold increase in drug resistance after intermittent exposure to increasing doses of cisplatin were compared to their parental counterparts, three well established relatively cisplatin sensitive germ cell tumor cell lines (NTERA-2, NCCIT, 2102EP). Cells were cultured and total RNA was isolated from all 6 cell lines in three independent experiments. RNA was converted into cDNA and quantitative RT-PCR was run using 384 well low density arrays covering almost all (738) known microRNA species of human origin.ResultsAltogether 72 of 738 (9.8%) microRNAs appeared differentially expressed between sensitive and resistant cell line pairs (NTERA-2R/NTERA-2 = 43, NCCIT-R/NCCIT = 53, 2102EP-R/2102EP = 15) of which 46.7-95.3% were up-regulated (NTERA-2R/NTERA-2 = 95.3%, NCCIT-R/NCCIT = 62.3%, 2102EP-R/2102EP = 46.7%). The number of genes showing differential expression in more than one of the cell line pairs was 34 between NTERA-2R/NTERA-2 (79%) and NCCIT-R/NCCIT (64%), and 3 and 4, respectively, between these two cell lines and 2102EP-R/2102EP (about 27%). Only the has-miR-10b involved in breast cancer invasion and metastasis and has-miR-512-3p appeared to be up-regulated (2-3-fold) in all three cell lines. The hsa-miR-371-373 cluster (counteracting cellular senescence and linked with differentiation potency), as well as hsa-miR-520c/-520h (inhibiting the tumor suppressor p21) were 3.9-16.3 fold up-regulated in two of the three cisplatin resistant cell lines. Several new micro-RNA species missing an annotation towards cisplatin resistance could be identified. These were hsa-miR-512-3p/-515/-517/-518/-525 (up to 8.1-fold up-regulated) and hsa-miR-99a/-100/-145 (up to 10-fold down-regulated).ConclusionExamining almost all known human micro-RNA species confirmed the miR-371-373 cluster as a promising target for explaining cisplatin resistance, potentially by counteracting wild-type P53 induced senescence or linking it with the potency to differentiate. Moreover, we describe for the first time an association of the up-regulation of micro-RNA species such as hsa-miR-512-3p/-515/-517/-518/-525 and down-regulation of hsa-miR-99a/-100/-145 with a cisplatin resistant phenotype in human germ cell tumors. Further functional analyses are warranted to gain insight into their role in drug resistance.

Iodine-131 dose dependent gene expression in thyroid cancers and corresponding normal tissues following the Chernobyl accident

The strong and consistent relationship between irradiation at a young age and subsequent thyroid cancer provides an excellent model for studying radiation carcinogenesis in humans. We thus evaluated differential gene expression in thyroid tissue in relation to iodine-131 (I-131) doses received from the Chernobyl accident. Sixty three of 104 papillary thyroid cancers diagnosed between 1998 and 2008 in the Ukrainian-American cohort with individual I-131 thyroid dose estimates had paired RNA specimens from fresh frozen tumor (T) and normal (N) tissue provided by the Chernobyl Tissue Bank and satisfied quality control criteria. We first hybridized 32 randomly allocated RNA specimen pairs (T/N) on 64 whole genome microarrays (Agilent, 4×44 K). Associations of differential gene expression (log2(T/N)) with dose were assessed using Kruskall-Wallis and trend tests in linear mixed regression models. While none of the genes withstood correction for the false discovery rate, we selected 75 genes with a priori evidence or P kruskall/P trend <0.0005 for validation by qRT-PCR on the remaining 31 RNA specimen pairs (T/N). The qRT-PCR data were analyzed using linear mixed regression models that included radiation dose as a categorical or ordinal variable. Eleven of 75 qRT-PCR assayed genes (ACVR2A, AJAP1, CA12, CDK12, FAM38A, GALNT7, LMO3, MTA1, SLC19A1, SLC43A3, ZNF493) were confirmed to have a statistically significant differential dose-expression relationship. Our study is among the first to provide direct human data on long term differential gene expression in relation to individual I-131 doses and to identify a set of genes potentially important in radiation carcinogenesis.

Circulating tumor cells in patients with testicular germ cell tumors

Purpose: Germ cell tumors (GCTs) represent the most frequent malignancies among young men, but little is known about circulating tumor cells (CTCs) in these tumors. Considering their heterogeneity, CTCs were investigated using two independent assays targeting germ cell tumor and epithelial cell–specific markers, and results were correlated with disease stage, histology, and serum tumor markers. Experimental Design: CTCs were enriched from peripheral blood (n = 143 patients) and testicular vein blood (TVB, n = 19 patients) using Ficoll density gradient centrifugation. For CTC detection, a combination of germ cell tumor (anti-SALL4, anti-OCT3/4) and epithelial cell–specific (anti-keratin, anti-EpCAM) antibodies was used. In parallel, 122 corresponding peripheral blood samples were analyzed using the CellSearch system. Results: In total, CTCs were detected in 25 of 143 (17.5%) peripheral blood samples, whereas only 11.5% of patients were CTC-positive when considering exclusively the CellSearch assay. The presence of CTCs in peripheral blood correlated with clinical stage (P < 0.001) with 41% of CTC positivity in patients with metastasized tumors and 100% in patients with relapsed and chemotherapy-refractory disease. Histologically, CTC-positive patients suffered more frequently from nonseminomatous primary tumors (P < 0.001), with higher percentage of yolk sac (P < 0.001) and teratoma (P = 0.004) components. Furthermore, CTC detection was associated with elevated serum levels of α-fetoprotein (AFP; P = 0.025), β-human chorionic gonadotropin (βHCG; P = 0.002), and lactate dehydrogenase (LDH; P = 0.002). Incidence and numbers of CTCs in TVB were much higher than in peripheral blood. Conclusions: The inclusion of germ cell tumor–specific markers improves CTC detection in GCTs. CTCs occur frequently in patients with more aggressive disease, and there is a gradient of CTCs with decreasing numbers from the tumor-draining vein to the periphery. Clin Cancer Res; 20(14); 3830–41. ©2014 AACR.

Predicting metastasized seminoma using gene expression

Study Type – Prognosis (cohort)

Expression and Localization of Lung Surfactant Proteins in Human Testis

Background Surfactant proteins (SPs) have been described in various tissues and fluids including tissues of the nasolacrimal apparatus, airways and digestive tract. Human testis have a glandular function as a part of the reproductive and the endocrine system, but no data are available on SPs in human testis and prostate under healthy and pathologic conditions. Objective The aim of the study was the detection and characterization of the surfactant proteins A, B, C and D (SP-A, SP-B, SP-C, SP-D) in human testis. Additionally tissue samples affected by testicular cancer were investigated. Results Surfactant proteins A, B, C and D were detected using RT-PCR in healthy testis. By means of Western blot analysis, these SPs were detected at the protein level in normal testis, seminoma and seminal fluid, but not in spermatozoa. Expression of SPs was weaker in seminoma compared to normal testicular tissue. SPs were localized in combination with vimentin immunohistochemically in cells of Sertoli and Leydig. Conclusion Surfactant proteins seem to be inherent part of the human testis. By means of physicochemical properties the proteins appear to play a role during immunological and rheological process of the testicular tissue. The presence of SP-B and SP-C in cells of Sertoli correlates with their function of fluid secretion and may support transportation of spermatozoa. In seminoma the expression of all SPs was generally weaker compared to normal germ cells. This could lead to a reduction of immunomodulatory and rheology processes in the germ cell tumor.

The Search for Biomarkers of Metastatic Seminoma

PURPOSE We screened 90 potential parameters as biomarkers of metastatic seminoma to facilitate detection and eliminate unnecessary therapeutic or diagnostic efforts. MATERIALS AND METHODS A total of 527 men with pure seminoma (diagnosed 2000 to 2011) were followed during therapy. More than 90 demographic/anamnestic (eg age, height, weight) histopathological parameters (testicular/tumor size, testicular intraepithelial neoplasia) and levels of tumor markers (eg α-fetoprotein, β-human chorionic gonadotropin, lactate dehydrogenase) in peripheral blood and testicular vein were collected for analysis via logistic regression. Previously described risk factors (tumors larger than 4 cm, infiltration of rete testis) were assessed separately. RESULTS Established parameters such as tumor length (p = 0.0003), involvement of lymphatic (p <0.0001) or vascular channels (p = 0.0009), extent of primary tumor (p <0.0001) and infiltration of the tunica albuginea (p = 0.02) as well as new biomarkers such as absence of testicular intraepithelial neoplasia in tumor bearing testis (p = 0.03), testicular volume (p = 0.04) and tumor volume (p = 0.02) showed a significant association with metastatic disease. This association was also true of lactate dehydrogenase, human chorionic gonadotropin and α-fetoprotein (p <0.0001 at maximum). However, the discriminatory capacity of these biomarkers (concordance or ROC area) did not exceed 65% when examined alone or in combination, and higher values (up to 80%) were detected for enzyme levels. A subset of metastatic seminoma (2% to 27%) was detectable with high accuracy (positive predictive value 92% to 100%) based on enzyme measurements (p <0.0006). CONCLUSIONS New biomarkers of metastatic seminoma were identified and previously described risk factors were validated. Further prospective studies of these novel parameters are warranted to verify our findings and to explore a potential use for detecting occult metastases.

A gene signature of primary tumor identifies metastasized seminoma

BACKGROUND The aim of this study was the prediction of metastatic status in seminoma based on examination of the primary tumor. METHODS Total RNA was isolated from metastasized seminoma (n = 10, T1N1-2M0), non-metastasized seminoma (n = 21, T1-3N0M0), and corresponding normal tissues. Pooled RNA from 10 biopsies of each tissue type was hybridized on whole genome microarrays for screening purposes. Ninety-two selected gene candidates were quantitatively examined using real-time quantitative polymerase chain reaction (RTQ-PCR). RESULTS Agreement in gene expression was 88% between the whole genome microarrays and RTQ-PCR. Metastasized seminoma showed 1,912 up-regulated and 2,179 down-regulated genes with ≥ 2-fold differences in gene expression compared non-metastasized seminoma. RTQ-PCR of selected genes showed that mean gene expression values were significantly reduced in metastasized compared with non-metastasized seminoma. The presence of metastases could be predicted based on an 85-gene expression signature by using logistic regression. Sensitivity and accuracy of the 10-fold cross-validation model were 77.8% and 84.2%, respectively. CONCLUSION A logistic regression model using an 85 gene expression signature allowed identification of metastasized seminoma from the primary tumor with a sensitivity of 77.8%.

Testicular prostheses in patients with testicular cancer - acceptance rate and patient satisfaction

BackgroundThe loss of a testicle to cancer involves much emotional impact to young males. Little is known about the number of patients with testicular germ cell tumour (GCT) who would accept a testicular prosthesis. Also, knowledge about the satisfaction of implant recipients with the device is limited.MethodsA retrospective chart analysis was performed on 475 consecutive GCT patients. Prior to orchiectomy, all patients were offered prosthesis insertion. Acceptance of implant was noted along with age, clinical stage, histology and year of surgery. 171 implant recipients were interviewed using an 18 item questionnaire to analyze satisfaction with the prosthesis. Statistical analysis involved calculating proportions and 95% confidence intervals. Multivariate analysis was performed to look for interrelations between the various items of satisfaction with the implant.Results26.9% of the patients accepted a prosthesis. The acceptance rate was significantly higher in younger men. Over-all satisfaction with the implant was “very high” and “high” in 31.1% and 52.4%, respectively. 86% would decide again to have a prosthesis. Particular items of dis-satisfaction were: implant too firm (52.4%), shape inconvenient (15.4%), implant too small (23.8%), position too high (30.3%). Living with a permanent partner had no influence on patient ratings. Multivariate analysis disclosed numerous inter-relations between the particular items of satisfaction.ConclusionsMore than one quarter of GCT patients wish to have a testicular prosthesis. Over-all satisfaction with implants is high in more than 80% of patients. Thus, all patients undergoing surgery for GCT should be offered a testicular prosthesis. However, surgeons should be aware of specific items of dis-satisfaction, particularly shape, size and consistency of the implant and inconvenient high position of the implant within the scrotum. Appropriate preoperative counselling is paramount.

Prognostic factors for tumor recurrence in patients with clinical stage I seminoma undergoing surveillance—A systematic review

OBJECTIVE To systematically evaluate evidence on prognostic factors for tumor recurrence in patients with clinical stage I seminoma undergoing surveillance. METHODS Systematic literature search conducted of Medline, Web of Science, Cochrane Library, and the conference proceedings of the ASCO, AUA, and EAU meetings (last search: October 2016), according to our prospectively registered protocol (PROSPERO registration number CRD42014009434). Identified records were reviewed according to the Cochrane Method Group of Prognosis Reviews recommendations and the PRISMA reporting guideline. Study quality was appraised with the Quality in Prognosis Studies (QUIPS) tool. RESULTS Nineteen studies reporting on 26 potential prognostic factors were included in our analysis. Among the most frequently reported factors, tumor size (continuous or dichotomized) was significantly associated with relapse in 10/14 studies with a hazard ratio (HR) ranging from 1.33 (95% confidence interval [CI]: 1.14-1.56) to 3.17 (95% CI: 1.08-9.26). Rete testis invasion was significantly associated with relapse in only 4/13 studies with a HR ranging from 1.18 (95% CI: 0.92-1.51) to 1.36 (95% CI: 0.81-2.28). Lymphovascular invasion, young age, and preoperative HCG level had no association with relapse. Our findings are limited by heterogeneity of study designs, potential reporting bias, and moderate-to-poor study quality. CONCLUSION In stage I seminoma, tumor size is the most valuable prognostic factor on which to base relapse risk and to counsel patients about adjuvant treatment. Large tumor size was defined quite inhomogenously among the included studies, so no distinct cutoff value for tumor size can be recommended. Other potential prognostic factors including rete testis invasion play a minor role in stage I seminoma.