Contralateral biopsies in patients with testicular germ-cell tumour—nuisance or new sense?

Abstract

It was a quantum leap in the understanding of the biology of testicular germ-cell tumours (GCTs) when Skakkebaek discovered the common progenitor cell of GCT in 1972 [1.Skakkebaek N.E. Possible carcinoma in situ of the testis.Lancet. 1972; ii: 516-517Abstract Scopus (569) Google Scholar]. He called that lesion carcinomain situ (CIS) of the testis, other terms have been suggested later, e.g. testicular intraepithelial neoplasia (TIN) or Intratubular germ-cell neoplasia unspecified (ITGCNU) [2.Emerson R.E. Ulbright T.M. Intratubular germ cell neoplasia of the testis and its associated cancers: the use of novel biomarkers.Pathology. 2010; 42: 344-355Abstract Full Text PDF PubMed Scopus (44) Google Scholar,3.Dieckmann K.P. Skakkebaek N.E. Carcinoma in situ of the testis: a review of biological and clinical features.Int J Cancer. 1999; 83: 815-822Crossref PubMed Scopus (211) Google Scholar]. Based on a number of pivotal clinico-pathological studies the Copenhagen Group was able to create the back-bone of the currently accepted theory of the pathogenesis of testicular GCTs [4.von der Maase H. Giwercman A. Müller J. Skakkebaek N.E. Management of carcinoma-in-situ of the testis.Int J Androl. 1987; 10: 209-220Crossref PubMed Scopus (70) Google Scholar, 5.Skakkebaek N.E. Berthelsen J.G. Giwercman A. Müller J. Carcinoma in situ of the testis: possible origin from gonocytes and precursor of all types of germ cell tumours except spermatocytoma.Int J Androl. 1987; 10: 19-28Crossref PubMed Scopus (647) Google Scholar, 6.Giwercman A. Bruun E. Frimodt-Moller C. Skakkebaek N.E. Prevalence of carcinoma in situ and other histopathological abnormalities in testes of men with a history of cryptorchidism.J Urol. 1989; 142: 998-1001Crossref PubMed Google Scholar]. According to that theory, CIS cells represent embryonal germ cells that fail to complete the normal maturation processin utero. Briefly, these cells are thought to remain widely unchanged in the testis and may proceed to invasive GCT following a cascade of additional steps after puberty [7.van der Zwan Y.G. Biermann K. Wolffenbuttel K.P. et al.Gonadal maldevelopment as risk factor for germ cell cancer: towards a clinical decision model.Eur Urol. 2014; (Sep 17 [epub ahead of print], doi: 10.1016/j.eururo.2014.07.011.)PubMed Google Scholar]. This fascinating theory of the pathogenesis of GCT acquired clinical relevance because the progenitor is supposed to be present in the testis many years before the clinical presentation of the malignancy. And as the progenitor cell is well detectable histopathologically, it appeared feasible to recognize GCT at a pre-malignant stage many years before the clinical outbreak [3.Dieckmann K.P. Skakkebaek N.E. Carcinoma in situ of the testis: a review of biological and clinical features.Int J Cancer. 1999; 83: 815-822Crossref PubMed Scopus (211) Google Scholar]. The practical application of this idea was facilitated by the assumption of a homogeneous distribution of CIS within the testis which was postulated by the Copenhagen group as a result ofex situ examinations of testicles with CIS [8.Berthelsen J.G. Skakkebaek N.E. Value of testicular biopsy in diagnosing carcinoma in situ testis.Scand J Urol Nephrol. 1981; 15: 165-168Crossref PubMed Scopus (90) Google Scholar]. Accordingly, a random surgical biopsy was considered to be sufficient for diagnosing the progenitor. Moreover, asde novo formation of CIS is not expected after birth, patients with a CIS-negative biopsy were considered to be at no further risk of GCT in that testicle. Although the homogeneous distribution of CIS has been challenged from the outset [9.Nistal M. Codesal J. Paniagua R. Carcinoma in situ of the testis in infertile men. A histological, immunocytochemical, and cytophotometric study of DNA content.J Pathol. 1989; 159: 205-210Crossref PubMed Scopus (45) Google Scholar,10.Loy V. Wigand I. Dieckmann K.P. Incidence and distribution of carcinoma in situ in testes removed for germ cell tumour: possible inadequacy of random testicular biopsy in detecting the condition.Histopathology. 1990; 16: 198-200Crossref PubMed Scopus (57) Google Scholar], several large-scale biopsy studies provided support to the theory [11.Holstein A.F. Lauke H. Histologic diagnostics of early testicular germ-cell tumor.Int J Urol. 1996; 3: 165-172Crossref PubMed Scopus (25) Google Scholar, 12.Dieckmann K.P. Loy V. Prevalence of contralateral testicular intraepithelial neoplasia in patients with testicular germ cell neoplasms.J Clin Oncol. 1996; 14: 3126-3132Crossref PubMed Scopus (138) Google Scholar, 13.Harland S.J. Cook P.A. Fossa S.D. et al.Intratubular germ cell neoplasia of the contralateral testis in testicular cancer: defining a high risk group.J Urol. 1998; 160: 1353-1357Crossref PubMed Scopus (112) Google Scholar]. Consequently, the European Guidelines pointed to the usefulness of contralateral biopsies in selected GCT patients [14.Albers P. Albrecht W. Algaba F. et al.EAU Guidelines on testicular cancer: 2011 update.Eur Urol. 2011; 60: 304-319Abstract Full Text Full Text PDF PubMed Scopus (285) Google Scholar]. In this issue of the journal, the Danish group is now putting a major question mark to the principal of taking testicular biopsies for the aim of early GCT diagnosis. The authors conducted a long-time observation of a large cohort of GCT patients (N = 3949) all of whom had a contralateral testicular biopsy negative for CIS at the time of orchiectomy (screened group). For comparison, the authors followed a group of GCT patients (N = 462) who were managed without biopsy (unscreened group). End point of the study was the occurrence of contralateral GCTs and according to the CIS theory, it was anticipated to find around 4% contralateral tumours in the unscreened and none in the screened group. In fact, the incidence of contralateral GCT was 3.2% in the unscreened group, however unexpectedly, a proportion of 1.3% contralateral tumours was found in the other group, despite the previous CIS-negative biopsy. As the difference between the groups was not statistically significant, the authors concluded that ‘there is no evidence to support screening (i.e. taking contralateral biopsies) in its present form in unselected patients’. First of all, the Danish group is to be commended for reporting these data that is in harsh conflict with their own theory. However, the final statement of the authors appears to be an over-reaction to the unappreciated results and thus represents a premature conclusion for at least four reasons. The first reason is a formal one: the Danish study is unique because of its size and the long observation time. However, on grounds of its non-randomized design, this study does achieve no more than level 3 or 2b at best regarding the formal classification of evidence. No systematic selection criteria were applied to establish the two study arms. Moreover, the groups are grossly divergent regarding sample size. The prerequisites for a level-2 study design are thus not met and the weight of formal evidence is too low, to draw any far reaching conclusion. The second reason is a statistical one: With the sample sizes published, the 95% confidence intervals (CIs) of the incidence rates in the two groups are in fact overlapping (3.2%; 95% CI 1.631% to 4.863% versus 1.3%; 95% CI 0.983–1.701; not specified in the article) and the difference is not significant. Yet, if putatively the control group would have comprised of the same size as the screened group (i.e.N = 3949) with the incidence still being 3.2% then the 95% CIs would be much narrower (2.889–3.794) with no more overlapping with the confidence limits of the screened group. So obviously, the main result of the study is heavily confounded by a methodological–statistical problem, i.e. the too small sample size of the control group. The third reason relates to histopathological technique employed in the study: Detecting CIS in testicular biopsy specimens is not trivial, histologically, because CIS is a rare lesion and not every pathologist is familiar with it. Therefore, it is of note that, in the present study, histological examination partly relied on local pathologists. Moreover, histopathological methods varied over time (1984–2012) with employment of sophisticated immunohistochemical markers only since 1996. So, failure of diagnosing CIS resulting from histopathological technique appears conceivable in at least a few cases. Accordingly, the incidence of contralateral CIS reported in the study is only 4.4%. This incidence is apparently lower than the incidence rates found in studies with central pathology review and standardized immunohistochemical work-up [11.Holstein A.F. Lauke H. Histologic diagnostics of early testicular germ-cell tumor.Int J Urol. 1996; 3: 165-172Crossref PubMed Scopus (25) Google Scholar, 12.Dieckmann K.P. Loy V. Prevalence of contralateral testicular intraepithelial neoplasia in patients with testicular germ cell neoplasms.J Clin Oncol. 1996; 14: 3126-3132Crossref PubMed Scopus (138) Google Scholar, 13.Harland S.J. Cook P.A. Fossa S.D. et al.Intratubular germ cell neoplasia of the contralateral testis in testicular cancer: defining a high risk group.J Urol. 1998; 160: 1353-1357Crossref PubMed Scopus (112) Google Scholar] and notably, it is much lower than reported in previous studies of the Copenhagen group where only central pathology examination was used [4.von der Maase H. Giwercman A. Müller J. Skakkebaek N.E. Management of carcinoma-in-situ of the testis.Int J Androl. 1987; 10: 209-220Crossref PubMed Scopus (70) Google Scholar,15.Hoei-Hansen C.E. Holm M. Rajpert-De Meyts E. Skakkebaek N.E. Histological evidence of testicular dysgenesis in contralateral biopsies from 218 patients with testicular germ cell cancer.J Pathol. 2003; 200: 370-374Crossref PubMed Scopus (157) Google Scholar]. The fourth reason relates to the topographic distribution of CIS in the testis and inappropriate surgical technique: the hypothesized homogeneous distribution of CIS has been questioned ever since its launch [10.Loy V. Wigand I. Dieckmann K.P. Incidence and distribution of carcinoma in situ in testes removed for germ cell tumour: possible inadequacy of random testicular biopsy in detecting the condition.Histopathology. 1990; 16: 198-200Crossref PubMed Scopus (57) Google Scholar,16.van Casteren N.J. Boellaard W.P. Dohle G.R. et al.Heterogeneous distribution of ITGCNU in an adult testis: consequences for biopsy-based diagnosis.Int J Surg Pathol. 2008; 16: 21-24Crossref PubMed Scopus (34) Google Scholar]. But, falsifying that hypothesis in a formal way was not easy because there is no experimental model of CIS [3.Dieckmann K.P. Skakkebaek N.E. Carcinoma in situ of the testis: a review of biological and clinical features.Int J Cancer. 1999; 83: 815-822Crossref PubMed Scopus (211) Google Scholar,7.van der Zwan Y.G. Biermann K. Wolffenbuttel K.P. et al.Gonadal maldevelopment as risk factor for germ cell cancer: towards a clinical decision model.Eur Urol. 2014; (Sep 17 [epub ahead of print], doi: 10.1016/j.eururo.2014.07.011.)PubMed Google Scholar]. Cases are rare and much time is required to identify false-negative biopsies. Forty-four cases with failed diagnosis of CIS had been documented up to 2003 [17.Dieckmann K.P. Loy V. False-negative biopsies for the diagnosis of testicular intraepithelial neoplasia (TIN)—an update.Eur Urol. 2003; 43: 516-521Abstract Full Text Full Text PDF PubMed Scopus (43) Google Scholar]. As a consequence, multiple sampling had been suggested [18.Kliesch S. Thomaidis T. Schütte B. et al.Update on the diagnostic safety for detection of testicular intraepithelial neoplasia (TIN).APMIS. 2003; 111: 70-74Crossref PubMed Scopus (54) Google Scholar]. Two-site biopsies increase the diagnostic sensitivity by 18% [19.Dieckmann K.P. Kulejewski M. Pichlmeier U. Loy V. Diagnosis of contralateral testicular intraepithelial neoplasia (TIN) in patients with testicular germ cell cancer: systematic two-site biopsies are more sensitive than a single random biopsy.Eur Urol. 2007; 51: 175-185Abstract Full Text Full Text PDF PubMed Scopus (86) Google Scholar]. The present report constitutes the final proof of the inhomogeneous, focal distribution of CIS. According to current knowledge, single biopsies as used throughout the study represent sub-standard leaving a considerable number of cases undetected. In all, the Danish study involves several major methodological weaknesses that strongly caution the rather apodictic conclusions. Clearly, the theory of CIS being the precursor of GCT remains undisputed, but the usefulness and the way of searching for CIS is challenged. The most important lesson to be learnt from this study is that a single testicular biopsy is not the right tool for searching for CIS. Likewise, high-quality immunohistochemical technique is indispensable. The other issue is whether at all it is worth taking biopsies? This crucial question cannot be answered solely with the principles of evidence-based medicine. The authors rightly point to opposing views on what the patient serves best in terms of morbidity. In fact, contralateral biopsies in GCT patients are obviously not a nuisance but they do make sense if carried out properly. Key elements are multiple sampling (e.g. double biopsies), careful processing of specimens by the surgeon and modern immunohistochemical work-up. Even then, sporadic false-negative biopsies may occur and this represents a departure from the old view and gives the procedure a new sense. Contralateral biopsies may provide a lot of valuable information not only with respect to early diagnosis of second GCT, but also in regard to spermatogenesis and future fertility chances of the patient. Thus, in light of the low surgical complication rate, offering a two-site biopsy to all GCT patients appears rational. However, restricting biopsies to high-risk patients with the aim of reducing the therapeutic burden could be a reasonable alternative [20.Rud C.N. Daugaard G. Rajpert-De Meyts E. et al.Sperm concentration, testicular volume and age predict risk of carcinoma-in-situ in contralateral testis of men with testicular germ-cell cancer.J Urol. 2013; 190: 2074-2080Crossref PubMed Scopus (23) Google Scholar]. Certainly, the benefits of biopsy will outweigh disadvantages. The author has declared no conflicts of interest.