# Germ cell neoplasia in situ (GCNIS)

Source: https://onco.cc/cancers/germ-cell-neoplasia-in-situ/  
OnCo record `germ-cell-neoplasia-in-situ` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Germ cell neoplasia in situ is the pre-cancer of testicular germ cell tumours: abnormal fetal-type germ cells sitting inside the seminiferous tubules, which will become seminoma or non-seminoma if left. It is found beside almost every testicular cancer and sometimes on its own in the other testis, where low-dose radiotherapy or surgery prevents a second cancer.

## Summary

The pre-invasive lesion of postpubertal testicular germ cell tumours was recognised in the early 1970s and carried several names (carcinoma in situ, intratubular germ cell neoplasia unclassified, testicular intraepithelial neoplasia) until the 2016 WHO consensus classification united them as germ cell neoplasia in situ (Histopathology 2016; Moch 2016). The cells resemble seminoma cells, express OCT4, PLAP and KIT, lie along the tubular basement membrane in tubules without spermatogenesis, and are the origin of seminoma, embryonal carcinoma, yolk sac tumour, choriocarcinoma and postpubertal teratoma, but not of spermatocytic tumour or prepubertal tumours. Testicular biopsy is the only established way to diagnose it; serum microRNA-371a-3p, a marker of invasive germ cell tumours, was raised in 51.9 percent of 27 men with isolated GCNIS (J Cancer Res Clin Oncol 2017).

How it differs from its parent: it is not yet a cancer, is not staged and raises no conventional serum markers; its importance is the roughly one in two chance of progression to invasive tumour over five years quoted in the classification literature, which drives contralateral biopsy policies in some countries.

How common: present beside almost all germ cell tumours; isolated GCNIS has no population figure in the sources read.

Treatment: for GCNIS in the remaining testis after orchidectomy for cancer, low-dose testicular radiotherapy (which preserves testosterone production but ends fertility), orchidectomy, or surveillance in men who wish to father children; chemotherapy for the invasive tumour eradicates GCNIS incompletely, so the contralateral testis is watched (NCI PDQ testicular summary for the invasive pathways).

## Fields

- Kind: Cancer
- Last checked: 2026-09-24
- Also known as: GCNIS; Intratubular germ cell neoplasia, unclassified; IGCNU; Testicular intraepithelial neoplasia; TIN; Carcinoma in situ of the testis; Germ cell neoplasia in situ (precursor)
- Tags: subtype-page; wave4; testicular; rare
- Group: genitourinary
- Burden: The precursor of almost every postpubertal testicular germ cell tumour, found in the tissue beside the tumour; as an isolated finding it is diagnosed on biopsy in men investigated for infertility, a contralateral tumour or cryptorchidism (Histopathology 2016). No incidence figure exists for the isolated lesion in the sources read.
- Subtypes: GCNIS adjacent to seminoma or embryonal carcinoma (the usual finding); Isolated GCNIS in the contralateral testis after orchidectomy; GCNIS in cryptorchid or infertile testes; Intratubular seminoma and intratubular embryonal carcinoma (intermediate stages)
- Biomarkers: OCT4, PLAP and KIT positive cells along the tubular basement membrane; Serum microRNA-371a-3p (research); Absent spermatogenesis in affected tubules; Isochromosome 12p in the invasive tumour that follows

## Sections of this record

The page is a hub with ten sections in reading order; large sections have their own page. The same plan as JSON: https://onco.cc/api/v1/cancers/germ-cell-neoplasia-in-situ/sections.json

- Overview (on the hub): The TL;DR, the family this cancer belongs to, the organ, who gets it and what the state of the art is. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/#overview
- What it is (on the hub): Anatomy, the subtypes and how they differ, how it is staged, and where advanced disease spreads. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/#what-it-is [4 subtypes]
- Finding it (on the hub): How it shows itself, how it is confirmed, what screening exists, and the biomarkers clinicians test for. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/#finding-it [4 biomarkers]
- Treating it (on the hub): The standard of care by setting, the medicines, surgery and radiotherapy named in it, and the regimens behind them. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/#treating-it [1 setting]
- Evidence (on the hub): Trials recruiting now, the landmark trials, the key papers and what they mean, the latest literature, and the milestones year by year. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/#evidence
- The science (on the hub): The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/#science
- Where you are (own page): Cases by country, the UK and NHS pathway and other country lenses, and the expert centres with trials on record. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/where-you-are/
- Living with it (on the hub): The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/#living-with-it [7 questions]
- What is coming (own page): Everything in development, the open problems and what is being done about them, the roadmaps, and what changed on this record. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/coming/
- Data (own page): Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked. https://onco.cc/cancers/germ-cell-neoplasia-in-situ/data/ [2 connected records]

## Standard of care

- Isolated GCNIS in the remaining testis: Low-dose testicular radiotherapy, orchidectomy, or surveillance in men wanting children; the invasive tumour that follows is treated as seminoma or non-seminoma. ([Testicular germ cell tumours](https://onco.cc/cancers/testicular/), [Seminoma](https://onco.cc/cancers/seminoma/), [Non-seminomatous germ cell tumour](https://onco.cc/cancers/non-seminoma/))

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Germ_cell_neoplasia_in_situ
- NCI PDQ: testicular cancer treatment: https://www.cancer.gov/types/testicular/treatment
- Moch 2016, European Urology: the 2016 WHO classification of urinary and male genital tumours, part A: https://doi.org/10.1016/j.eururo.2016.02.029
- Histopathology 2016: germ cell neoplasia in situ, evolution of the nomenclature: https://doi.org/10.1111/his.12958
- J Cancer Res Clin Oncol 2017: serum microRNA-371a-3p in 27 patients with germ cell neoplasia in situ: https://doi.org/10.1007/s00432-017-2490-7

## Connected records

- cancers: [Embryonal carcinoma of the testis](https://onco.cc/cancers/embryonal-carcinoma-testis/), [Non-seminomatous germ cell tumour](https://onco.cc/cancers/non-seminoma/), [Seminoma](https://onco.cc/cancers/seminoma/), [Spermatocytic tumour of the testis](https://onco.cc/cancers/spermatocytic-tumour/), [Testicular germ cell tumours](https://onco.cc/cancers/testicular/)
- terms: [Carcinoma in situ (CIS)](https://onco.cc/terms/carcinoma-in-situ/), [Tumour markers (CEA, LDH, chromogranin, thyroglobulin)](https://onco.cc/terms/tumour-markers/)

---
JSON: https://onco.cc/api/v1/entities/germ-cell-neoplasia-in-situ.json