Prognostic factors for relapse in patients with clinical stage I testicular cancer: protocol for a Danish nationwide cohort study

Prognostic factors for relapse in patients with clinical stage I testicular non-seminoma: A nationwide, population-based cohort study

BACKGROUND

Approximately 30% of patients with clinical stage I non-seminoma (CSI-NS) relapse. Current risk stratification is based on lymphovascular invasion (LVI) alone. The extent to which additional tumor characteristics can improve risk prediction remains unclear.

OBJECTIVE

To determine the most important prognostic factors for relapse in CSI-NS patients.

DESIGN, SETTING, AND PARTICIPANTS

Population-based cohort study including all patients with CSI-NS diagnosed in Denmark between 2013 and 2018 with follow-up until 2022. Patients were identified in the prospective Danish Testicular Cancer database. By linkage to the Danish National Pathology Registry, histological slides from the orchiectomy specimens were retrieved.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Histological slides were reviewed blinded to the clinical outcome. Clinical data were obtained from medical records. The association between prespecified potential prognostic factors and relapse was assessed using Cox regression analysis. Model performance was evaluated by discrimination (Harrell's C-index) and calibration.

RESULTS

Of 453 patients included, 139 patients (30.6%) relapsed during a median follow-up of 6.3 years. Tumor invasion into the hilar soft tissue of the testicular hilum, tumor size, LVI and embryonal carcinoma were independent predictors of relapse. The estimated 5-year risk of relapse ranged from < 5% to > 85%, depending on the number of risk factors. After internal model validation, the model had an overall concordance statistic of 0.75. Model calibration was excellent.

CONCLUSION AND RELEVANCE

The identified prognostic factors provide a much more accurate risk stratification than current clinical practice, potentially aiding clinical decision-making.

Prognostic Factors for Relapse in Patients With Clinical Stage I Testicular Seminoma: A Nationwide, Population-Based Cohort Study

PURPOSE

Approximately 20% of patients with clinical stage I seminoma relapse. Tumor size and rete testis invasion have been identified as risk factors for relapse. However, the level of evidence supporting the use of these risk factors in clinical decision making is low. Previous studies have been hampered by selection bias and variable pathology reporting that limit interpretation and generalization of results. We assessed prognostic factors for relapse in an unselected nationwide population-based setting with centralized pathology review.

METHODS

Patients with clinical stage I seminoma diagnosed from January 2013 to December 2018 were identified in the prospective Danish Testicular Cancer database. By linkage to the Danish National Pathology Registry, histologic slides from the orchiectomy specimens were retrieved and reviewed blinded to the clinical outcome. Clinical data were obtained from medical records with follow-up until July 2022. The association between prespecified potential clinical and histopathologic prognostic factors and relapse was assessed by the use of Cox regression analysis.

RESULTS

Of 924 patients included, 148 (16%) patients relapsed during a median follow-up of 6.3 years. Invasion of the testicular hilum (rete testis and hilar soft tissue), lymphovascular invasion, and elevated preorchiectomy levels of β-human chorionic gonadotropin and lactate dehydrogenase were independent predictors of relapse. The estimated 5-year risk of relapse ranged from 6% in patients with no risk factors to 62% in patients with all four risk factors with tumor extension into the hilar soft tissue of the testicular hilum. After internal model validation, the prognostic model had an overall concordance statistic of 0.70.

CONCLUSION

The provided prognostic factors could replace current risk factors in guidelines and be used in future studies investigating risk-adapted follow-up and treatment strategies.

A Validated Algorithm for Register-Based Identification of Patients with Relapse of Clinical Stage I Testicular Cancer

Purpose

The Danish Testicular Cancer (DaTeCa) database aims to monitor and improve quality of care for testicular cancer patients. Relapse data registered in the DaTeCa database rely on manual registration. Currently, some safeguarding against missing registrations is attempted by a non-validated register-based algorithm. However, this algorithm is inaccurate and entails time-consuming medical record reviews. We aimed (1) to validate relapse data as registered in the DaTeCa database, and (2) to develop and validate an improved register-based algorithm identifying patients diagnosed with relapse of clinical stage I testicular cancer.

Patients and Methods

Patients registered in the DaTeCa database with clinical stage I testicular cancer from 2013 to 2018 were included. Medical record information on relapse data served as a gold standard. A pre-specified algorithm to identify relapse was tested and optimized on a random sample of 250 patients. Indicators of relapse were obtained from pathology codes in the Danish National Pathology Register and from diagnosis and procedure codes in the Danish National Patient Register. We applied the final algorithm to the remaining study population to validate its performance.

Results

Of the 1377 included patients, 284 patients relapsed according to the gold standard during a median follow-up time of 5.9 years. The completeness of relapse data registered in the DaTeCa database was 97.2% (95% confidence interval (CI): 95.2-99.1). The algorithm achieved a sensitivity of 99.6% (95% CI: 98.7-100), a specificity of 98.9% (95% CI: 98.2-99.6), and a positive predictive value of 95.9% (95% CI: 93.4-98.4) in the validation cohort (n = 1127, 233 relapses).

Conclusion

The registration of relapse data in the DaTeCa database is accurate, confirming the database as a reliable source for ongoing clinical quality assessments. Applying the provided algorithm to the DaTeCa database will optimize the accuracy of relapse data further, decrease time-consuming medical record review and contribute to important future clinical research.

Pathological predictors of metastatic disease in testicular non-seminomatous germ cell tumors: which tumor-node-metastasis staging system?

Pathological risk factors for metastatic disease in patients with testicular non-seminomatous germ cell tumors are debated. The tumor-node-metastasis (TNM) classification eighth edition for testicular cancers includes divergent versions, by the International Union Against Cancer (UICC) and by the American Joint Committee for cancer (AJCC). We investigated pathological predictors of metastatic disease at presentation in 219 non-seminomatous germ cell tumors with reference to both classifications. Age, tumor size, percentage of embryonal carcinoma, lymphovascular invasion, invasion of stromal rete testis, hilar soft tissue, epididymis, spermatic cord, and tunica vaginalis, as well as tumor at spermatic cord margin, were assessed and correlated with clinical stage at presentation. Of the 219 NSGCT cases, 151 (69%) were clinical stage I, 68 (31%) were clinical stage II/III. On univariate analysis, tumor size (P = 0.028), percentage of embryonal carcinoma (P = 0.004), lymphovascular invasion (P = 0.001), stromal rete testis invasion (P = 0.001), hilar soft tissue invasion (P = 0.010), epididymis invasion (P = 0.010), direct spermatic cord invasion (P = 0.001), and tumor at spermatic cord margin ((P = 0.009) were associated with higher clinical stage. On multivariate analysis, lymphovascular invasion (P = 0.003), tumor size (P = 0.005), percentage of embryonal carcinoma (P = 0.005), stromal rete testis invasion (P = 0.008) remained significant. A tumor size of 6 cm and an embryonal carcinoma percentage of 70% were the significant cut-off values. We conclude that in addition to lymphovascular invasion, stromal rete testis invasion, tumor size, and embryonal carcinoma percentage are strong predictors of metastatic disease at presentation and their inclusion should be considered in any future TNM revision. Further, our results support the changes in the AJCC TNM eighth edition as invasion of the epididymis and hilar soft tissue were both univariately significant.

Promoter methylation of DNA homologous recombination genes is predictive of the responsiveness to PARP inhibitor treatment in testicular germ cell tumors

Testicular germ cell tumors (TGCTs) are the most common cancers in men aged 15-39 years and are divided into two major groups, seminomas and nonseminomas. Novel treatment options are required for these patients, to limit side effects of chemotherapy. We hypothesized that promoter methylation of relevant homologous recombination (HR) genes might be predictive of response to poly-ADP ribose polymerase inhibitors (PARPis) in TGCTs. We report a study pipeline combining in silico, in vitro, and clinical steps. By using several databases and in silico tools, we identified BRCA1, RAD51C, PALB2, RAD54B, and SYCP3 as the most relevant genes for further investigation and pinpointed specific CpG sites with pronounced negative correlation to gene expression. Nonseminomas displayed significantly higher methylation levels for all target genes, where increased methylation was observed in patients with more differentiated subtypes and higher disease burden. We independently performed second-line targeted validation in tissue series from TGCT patients. A moderate and/or strong anti-correlation between gene expression (assessed by RNA-sequencing) and promoter methylation (assessed by 450k array) was found, for all of the targets. As a proof of concept, we demonstrated the sensitivity of TGCT cell lines to Olaparib, which associated with differential methylation levels of a subset of targets, namely BRCA1 and RAD51C. Our findings support the use of HR genes promoter methylation as a predictor of the therapeutic response to PARPis in patients with TGCT.

Epigenetic alterations as therapeutic targets in Testicular Germ Cell Tumours : current and future application of 'epidrugs'

Testicular germ cell tumours (TGCTs) are heterogeneous neoplasms mostly affecting young-adult men. Despite high survival rates, some patients with disseminated disease acquire cisplatin resistance, entailing the need for less toxic therapies. Epigenetic alterations constitute an important feature of TGCTs, which are also implicated in resistance mechanism(s). These alterations might be used as potential targets to design epigenetic drugs. To date, several compounds have been explored and evaluated regarding therapeutic efficacy, making use of pre-clinical studies with in vitro and in vivo models, and some have already been explored in clinical trials. This review summarizes the several epigenetic mechanisms at play in these neoplasms, the current challenges in the field of TGCTs and critically reviews available data on 'epidrugs' in those tumours.