The next edition of the World Health Organisation (WHO) Blue Book will change how doctors classify testicular tumours, according to a specialist speaking at a recent cancer conference. Prof Dan Berney, a Consultant Pathologist at Barts Health NHS Trust in the UK, said the new classification system will replace the term “teratoma with somatic malignancy” with “GCT with somatic changes.” This shift aims to ensure patients with these specific tumours continue to receive care from genitourinary oncologists rather than being referred to sarcoma specialists, as the pathology of these growths is more closely related to germ cell tumours than to the somatic counterparts they resemble.
New names for cancer subtypes
The updated WHO guidelines will introduce specific names for different types of somatic transformation within these tumours. A rhabdomyosarcoma-like component will be called a sarcoma-like tumour of germ cell origin (rhabdomyeloblastic phenotype), while unclassified sarcoma will be referred to as the undifferentiated phenotype. Other changes include renaming embryonic-type neuroectodermal tumours to embryonic-type neuroductal tumour of germ cell origin. Additionally, somatic-type enteric adenocarcinoma and squamous cell carcinoma will be classified as enteric and squamous phenotypes, respectively. Tumours containing both conventional and somatic components will be defined by the proportion of their various elements, such as yolk sac or seminoma.
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Prof Berney noted that these tumours often display widespread aneuploidy, distinct epigenetic signatures, and mutations that are rare in typical testicular germ cell tumours. He stated that identifying the presence of a somatic malignancy component may be more clinically significant than determining the precise histological subtype. The reclassification ensures that patients are not “hived off” into the sarcoma community, as there is still a chance these tumours will respond to germ cell-type therapies.
Risk factors for recurrence
Aside from the naming changes, the upcoming WHO edition will introduce new prognostic factors for patients with clinical stage 1 seminoma and non-seminoma. These additions are particularly relevant for the 20 to 30 percent of patients for whom orchidectomy, the surgical removal of the testicle, does not result in a cure. After years of debate, the guidelines will include invasion of soft tissues, specifically around the hilum, as a critical prognostic indicator in stage 1 seminomas.
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This change follows a Danish study published in the Journal of Clinical Oncology in 2024. The analysis showed that while rete testis invasion is associated with a hazard ratio of 1.81, the presence of rete testis invasion combined with hilar soft tissue invasion increases the hazard ratio to 2.83. Prof Berney emphasized that these factors are strong predictors of relapse. The study also identified lymphovascular invasion (LVI) as a significant risk factor, with a hazard ratio of 1.82. Raised levels of b-hCG and LDH were also linked to higher recurrence rates, with hazard ratios of 1.89 and 1.67, respectively. Patients with all four of these risk factors face a 62 percent chance of recurrence compared to just 6 percent for those with none.
