# Johannes Fibiger
Johannes Andreas Grib Fibiger (23 April 1867 – 30 January 1928) was a Danish physician and pathologist at Copenhagen University who was awarded the 1926 [Nobel Prize in Physiology or Medicine](https://www.edgepedia.org/nobel-prize-in-physiology-or-medicine) "for his discovery of the Spiroptera carcinoma", a parasitic worm whose larvae he believed caused stomach cancer in rats.[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) • [2](https://www.nobelprize.org/prizes/medicine/1926/fibiger/facts/) • [9](https://academic.oup.com/oncolo/article/22/5/542/6438922) His chief work concerned the alleged cancer-causing role of the nematode later named Gongylonema neoplasticum in some species of rats.[3](https://europepmc.org/article/med/11625107) Later research showed that the primary cause of the rats' cancer was a lack of vitamin A, not the worm, and the prize is now widely cited as an award for a refuted discovery.[2](https://www.nobelprize.org/prizes/medicine/1926/fibiger/facts/) • [4](https://www.acpjournals.org/doi/10.7326/0003-4819-116-9-765)
| Fact | Detail |
|---|---|
| Born | Silkeborg, Denmark, 23 April 1867[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) |
| Died | Copenhagen, 30 January 1928[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) |
| Doctorate | University of Copenhagen, 1895, thesis on the bacteriology of diphtheria[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) |
| Professorship | Professor of Pathological Anatomy and Director of the Institute of Pathological Anatomy, Copenhagen, from 1900 until his death in 1928[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) • [5](https://www.sciencedirect.com/science/article/abs/pii/S0065230X04920015) |
| Nobel Prize | 1926 Physiology or Medicine, "for his discovery of the Spiroptera carcinoma"; received in 1927[2](https://www.nobelprize.org/prizes/medicine/1926/fibiger/facts/) |
| Later verdict | The rats' cancer was caused primarily by vitamin A deficiency; the worm hypothesis was refuted[2](https://www.nobelprize.org/prizes/medicine/1926/fibiger/facts/) • [4](https://www.acpjournals.org/doi/10.7326/0003-4819-116-9-765) |
| Nominations | 16 Nobel nominations over 6 years before the award[6](https://academia.dk/MedHist/Biografier/fibiger-bio.php) |
## Career and positions
Fibiger gained his bachelor's degree in 1883 and qualified as a doctor in 1890.[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) From 1891 to 1894 he was assistant to Professor C. J. Salomonsen at the Department of Bacteriology of Copenhagen University, after studying under [Robert Koch](https://www.edgepedia.org/robert-koch) and [Emil von Behring](https://www.edgepedia.org/emil-von-behring).[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) While an Army reserve doctor at Blegdam Hospital in Copenhagen from 1894 to 1897 he completed his doctoral thesis on the bacteriology of diphtheria, receiving his doctorate from the [University of Copenhagen](https://www.edgepedia.org/university-of-copenhagen) in 1895.[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/)
He was prosector at the University's Institute of Pathological Anatomy from 1897 to 1900, and Principal of the Laboratory of Clinical Bacteriology of the Army from 1890 to 1905.[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) In 1900 he was appointed Professor of Pathological Anatomy at Copenhagen University and Director of the Institute of Pathological Anatomy, a position he held until his death in 1928.[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) • [5](https://www.sciencedirect.com/science/article/abs/pii/S0065230X04920015) In 1905 he became Director of the Central Laboratory of the Army and Consultant Physician to the Army Medical Service.[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/)
## Representative work
The work for which Fibiger is known was carried out in 1907–13, when he suspected a roundworm as the cause of cancer in rats and declared cockroaches the worm's intermediate host.[2](https://www.nobelprize.org/prizes/medicine/1926/fibiger/facts/) • [6](https://academia.dk/MedHist/Biografier/fibiger-bio.php) In 1913, six or seven years after the first observation, he presented the investigations and indicated that rats that had ingested worm larvae by eating cockroaches developed cancer.[2](https://www.nobelprize.org/prizes/medicine/1926/fibiger/facts/) • [7](https://biografiskleksikon.lex.dk/Johannes_Fibiger_-_l%C3%A6ge/) Accounts of the period describe the finding that healthy rats could develop cancer upon infection with the internal worm Spiroptera neoplastica as a discovery that stimulated cancer research worldwide.[6](https://academia.dk/MedHist/Biografier/fibiger-bio.php) Fibiger is credited with the first controlled induction of cancer in laboratory animals, although that priority is tied to experiments later found not reproducible.[8](https://www.whonamedit.com/doctor.cfm/1443.html) • [3](https://europepmc.org/article/med/11625107)
## The 1926 Nobel Prize
In 1923 the Swedish professor of pathology [Folke Henschen](https://www.edgepedia.org/folke-henschen) nominated Fibiger to the Nobel committee, writing—according to *An Analysis of a Wrong Nobel Prize—Johannes Fibiger, 1926: A Study in the Nobel Archives*—that the importance of Fibiger's works lay in him being able, reproducibly in controlled experiments, to induce cancer in rats.[5](https://www.sciencedirect.com/science/article/abs/pii/S0065230X04920015) He had accumulated 16 nominations over 6 years before receiving the award.[6](https://academia.dk/MedHist/Biografier/fibiger-bio.php) The 1926 prize, with affiliation at Copenhagen University, was given "for his discovery of the Spiroptera carcinoma", and Fibiger received it one year later, in 1927.[2](https://www.nobelprize.org/prizes/medicine/1926/fibiger/facts/)
## What later research showed
The 1926 prize was awarded for the subsequently refuted discovery that gastric carcinoma in rats was caused by the nematode Spiroptera carcinoma, framing the award around a hypothesis rather than a confirmed finding.[4](https://www.acpjournals.org/doi/10.7326/0003-4819-116-9-765) It later turned out that the primary cause of the rats' cancer was a lack of vitamin A, and that the worm larvae only caused damage to tissue where the cancer could begin developing.[2](https://www.nobelprize.org/prizes/medicine/1926/fibiger/facts/) Difficulties with the species of Gongylonema, dietary factors, the vitamin A deficiency, and the impossibility of reproducing his results brought contestation of his work, and the prize has by many been regarded as a mistake by the Nobel committee.[3](https://europepmc.org/article/med/11625107) • [6](https://academia.dk/MedHist/Biografier/fibiger-bio.php)
## Honors and legacy
Fibiger's Spiroptera investigations inspired Japanese researchers to show that coal tar could induce skin cancer in rabbits and mice.[7](https://biografiskleksikon.lex.dk/Johannes_Fibiger_-_l%C3%A6ge/) He was a founder-member and joint-editor of Acta Pathologica et Microbiologica Scandinavica, President of the Danish Medical Society, and honorary doctor of the Universities of Paris and Louvain.[1](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/) He was elected to Videnskabernes Selskab in 1916, was vice-president of the Internationale Vereinigung für Krebsforschung from its founding in 1908 and its president 1913–1920, chaired the cancer committee from 1922, received the Nordhoff-Jungske international cancer prize in 1923, was the university's rector 1925–26, and received honorary doctorates from Louvain and Paris in 1927 before receiving the Nobel Prize in October that year.[7](https://biografiskleksikon.lex.dk/Johannes_Fibiger_-_l%C3%A6ge/) The cancer-causing action of some parasitic helminths such as [Schistosoma](https://www.edgepedia.org/schistosoma) is now recognized, giving the general idea of parasite-induced cancer a footing that Fibiger's own worm did not have.[3](https://europepmc.org/article/med/11625107)
## References
1. [Johannes Fibiger – Biographical, Nobel Foundation](https://www.nobelprize.org/prizes/medicine/1926/fibiger/biographical/)
2. [Johannes Fibiger – Facts, Nobel Foundation](https://www.nobelprize.org/prizes/medicine/1926/fibiger/facts/)
3. [A challenged Nobel Prize: Johannes Fibiger, 1926, via Europe PMC](https://europepmc.org/article/med/11625107)
4. [Johannes Fibiger and His Nobel Prize for the Hypothesis That a Worm Causes Stomach Cancer, Annals of Internal Medicine](https://www.acpjournals.org/doi/10.7326/0003-4819-116-9-765)
5. [An Analysis of a Wrong Nobel Prize, Johannes Fibiger, 1926: A Study in the Nobel Archives, Advances in Cancer Research](https://www.sciencedirect.com/science/article/abs/pii/S0065230X04920015)
6. [Johannes Fibiger, Academia.dk medicinhistorie biografi](https://academia.dk/MedHist/Biografier/fibiger-bio.php)
7. [Johannes Fibiger – læge, Dansk Biografisk Leksikon](https://biografiskleksikon.lex.dk/Johannes_Fibiger_-_l%C3%A6ge/)
8. [Johannes Andreas Grib Fibiger, Whonamedit](https://www.whonamedit.com/doctor.cfm/1443.html)
9. [academic.oup.com](https://academic.oup.com/oncolo/article/22/5/542/6438922)
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*Topic: Encyclopedia › Life and health › Life and health scientists › Life scientists › Researchers in cancer biology › Carcinogenesis and cancer virology*
*Initially written Sep 21, 2026 · Reviewed: Sep 25, 2026 · Edited: Sep 25, 2026; Oct 11, 2026 · Last review: Sep 25, 2026*
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