With the relatively low prevalence of testicular cancer, compared with other solid tumors, advancements in care for its patients are rarely headline grabbing. After all, with an overall 5-year relative survival rate of approximately 95 percent, it is one of the most curable cancers.
However, the curative treatments can have devastating effects on the quality of life of survivors – especially those diagnosed young. That is why researchers like João Lobo – Pathologist at IPO Porto and Assistant Professor at the Department of Pathology and Molecular Immunology, ICBAS-UP, Portugal – are working hard to develop precision diagnostics to guide more personalized treatments for patients with testicular cancer.
In between presenting on this very topic at the European Congress of Pathology in Vienna, Lobo took time out to tell us about his contribution to these efforts.
What are the gaps in diagnostics for testicular cancer?
Unlike many tumors, testicular cancer is not definitively diagnosed through biopsy – the tissue sampling procedure remains contraindicated for these patients. This limitation creates an urgent clinical need for non-invasive diagnostic tools.
Currently, the standard approach relies on imaging to identify suspicious masses, followed by surgical removal of the entire testicle (orchiectomy) with diagnosis confirmed only after the tissue has been examined. However, imaging has its limitations: while it can reliably detect the presence of a mass, it can't determine which specific cancer type – or histology – is present. Given that benign inflammatory conditions such as orchitis or epididymitis may mimic malignant tumors on imaging alone, this imprecision can lead to unnecessary surgery in some cases.
Clinicians do have serum-based biomarkers available for workup of testicular germ cell tumors, which represent more than 90 percent of testicular cancers. The three traditional markers – alpha-fetoprotein (AFP), lactate dehydrogenase (LDH), and human chorionic gonadotropin (hCG) – have become standard for patient staging and follow-up monitoring. Yet these markers also have limitations – while they can be elevated in up to 60 percent of patients at diagnosis, they remain normal in the remaining 40 percent. More problematically, they are histology-dependent, meaning certain cancer types fail to produce detectable marker elevations. Seminoma and embryonal carcinoma, for instance, often don't raise these markers at all.
How are emerging precision diagnostics aiming to address these issues?
A specific microRNA cluster – microRNA-371∼373 – has emerged as a breakthrough marker for germ cell tumors of the testis. Identified in a landmark 2006 study, this cluster proved highly specific for these cancers. In the years since, dozens of research groups worldwide have worked to translate this discovery into clinical practice. My institution was involved – as a national reference center for testicular cancer – and it was a major focus of my PhD.
Recently, microRNA-371a-3p was commercially developed as an in vitro diagnostic (IVD) test with full regulatory approval for clinical use in Europe. Since August 2024, our cancer center has systematically offered the microRNA test to all patients presenting with testicular masses and throughout their disease follow-up, analyzing more than 120 samples to date.
Our early results have been promising, with clinicians reporting that the test provides valuable diagnostic information. However, the microRNA test remains outside current clinical guidelines – it is not yet recognized as a minimum requirement for testicular cancer diagnosis. The ongoing validation work in diverse patient populations aims to establish its clinical value and potentially pave the way for broader guideline adoption.
What clinical impact have you seen since introducing the microRNA test?
The test has been particularly valuable in managing a challenging subset of patients with small testicular masses. When detected, they often present a diagnostic dilemma: many such lesions turn out to be benign or non-cancerous yet distinguishing them from malignant germ cell tumors is difficult. A negative microRNA test result, in the proper clinical context, reassures clinicians that the patient may safely remain under active surveillance rather than undergoing immediate surgery. A positive result strengthens the decision to undergo orchiectomy
The biomarker also shows promise as an early warning system for disease recurrence. By introducing the microRNA test into disease surveillance, clinicians may be able to detect relapses earlier while reducing the number of imaging studies required. This is particularly significant for young men with testicular cancer, for whom the long-term consequences of treatment weigh heavily – largely due to the cumulative effects of chemotherapy and the radiation exposure from repeated CT scans during follow-up monitoring.
Early detection of recurrence would allow for intervention with lower doses of chemotherapy, minimizing treatment toxicity and long-term harm.
What needs to change in order to encourage wider adoption of the test?
Every review article on the subject now emphasizes the need for standardized protocols that all laboratories can follow. A validated, commercially available IVD test provides exactly this kind of standardization. Because the assay follows a closed, defined pipeline with strict procedural requirements, all users must adhere to the same protocol, ensuring consistency across institutions and populations.
Pathologists occupy a critical position in this transition, responsible for ensuring proper sample handling, managing pre-analytical variables, and standardizing how results are reported.
What challenges remain for this research?
The microRNA test has one notable blind spot. Teratoma, the most differentiated form of testicular germ cell tumor, does not produce detectable elevations of the microRNA-371∼373 cluster. This represents more than a minor limitation: teratomas behave differently from other germ cell tumors, particularly when metastases develop after chemotherapy treatment, often requiring distinct clinical management strategies. When a patient harbors a teratoma, the microRNA biomarker alone cannot provide the diagnostic reassurance or prognostic information that clinicians need.
Investigators worldwide are actively searching for an alternative biomarker specific to teratoma that could be used in conjunction with the microRNA-371∼373 cluster, creating a complementary two-marker panel. The challenge has become sufficiently prominent that a recent review article explicitly labeled it "the teratoma challenge," framing the search for a teratoma biomarker as one of the field's key outstanding problems.
What is your vision for personalized medicine for patients with testicular cancer?
Ideally, we need a minimally invasive test combining both sensitivity and specificity. When acting on biomarker results, we need to be confident that the patient actually needs treatment. The research on overtreatment in testicular cancer is sobering – survivors exposed to cisplatin chemotherapy experience higher rates of second malignancies, diabetes, cardiovascular disease, metabolic syndrome, and infertility. These are significant long-term consequences.
A biomarker that could guide us toward de-escalation would be transformative. With the right diagnostic tool, we could confidently tell a patient in their twenties or thirties: "We don't need to treat you with chemotherapy right now. We can monitor you closely and keep this under control." That would be genuinely helpful, given how young these patients are.
How can precision diagnostics become more widely available if they're more expensive than traditional serum markers?
The classical serum markers are cheaper and faster – they're part of routine assessment at most hospitals. But the microRNA test isn't actually as complicated as the terminology might suggest. It's one reaction, one target. We're measuring a single microRNA using standard quantitative PCR. It's not an elaborate, multi-omics panel. You need just 100 to 200 microliters of serum or plasma, and a straightforward RNA extraction. So technically, the barrier to implementation isn't complexity; it's infrastructure and expertise.
At the Department of Pathology at IPO Porto, we run the microRNA test once per week: we begin the RNA extraction Thursday afternoon, continue the workflow Friday morning, and have the reports completed by early Friday afternoon.
How can we best facilitate patient access to this test?
I think the practical solution aligns well with what's already recommended for testicular cancer care: centralizing these patients at specialized reference centers. This makes sense for multiple reasons. Testicular cancer is relatively uncommon, so it requires teams with genuine expertise – not just in the molecular testing, but in the histopathological review of these tumors. The European Society for Medical Oncology recommends that pathologists should have experience reviewing at least 30 testicular cancer cases per year to maintain competency.
Establishing the microRNA test at reference centers creates a workable model. Patients can be referred to these centers, where both the diagnostic expertise and the testing infrastructure already exist. It's certainly doable. We still need to standardize some pre-analytical procedures – how samples are collected, stored, and processed – and multiple groups are actively working on that. But I think within the near future, we'll have those details sorted out and a clear pathway for implementation.
What are your main research priorities moving forward?
The teratoma challenge remains a critical priority. We will continue the search for a complementary biomarker – something specifically sensitive to teratomas. If we could develop that and combine it with microRNA-371a-3p into a unified diagnostic panel, that would be genuinely transformative.
In parallel, our research group is pursuing several other directions. Germ cell tumors have a fascinating biology that draws directly from embryonic and germ cell development, which is deeply rooted in epigenetics. What's striking is that from a genomics perspective, these tumors have a relatively low mutational burden – there aren't many mutations driving them. But from an epigenetic standpoint, they're an extremely active and promising research area. Our research team, the Cancer Biology and Epigenetics Group of IPO Porto, is particularly focused on testing epigenetic compounds –including DNMT and HDAC inhibitors – that target the epigenetic alterations underlying these cancers. We're working extensively with cell lines, exposing them to various epigenetic inhibitors to understand which are most effective.
One of my PhD students, Nuno Tavares, recently won a grant to take this research to the United States and test these compounds in mouse models, which will be a crucial step toward potential clinical translation. I'm genuinely excited about that prospect.
Are there other emerging approaches you're watching?
Circulating tumor DNA in germ cell tumors is still an underdeveloped area – with only one or two published studies so far. But this is an emerging field, and I think there's real potential to explore it further in testicular cancer. Overall, this is an exciting time for precision diagnostics and targeted therapies in this disease, with multiple promising avenues being pursued simultaneously.
What is your message of hope for patients?
We know that the tumors are very responsive to chemotherapy – cisplatin has been transformational in this area. But, alongside curative treatment, we must remain mindful of the quality of life of this patient group and reduce the degree of over-treatment.
The approach of combining pathology, epigenetics, and developmental biology is putting us on the right trajectory to discover new biomarkers and treatments. And we'll keep going with the research until patients with testicular cancer can be offered diagnostically informed, tailored treatment pathways.
Newsletters
Receive the latest pathologist news, personalities, education, and career development – weekly to your inbox.
