Cells settling in an organ other than the correct one during embryogenesis are often the cause of rare ovarian and pancreatic cancers which affect only young women, researchers at the University of Geneva (UNIGE) and the University Hospitals of Geneva (HUG) have found. The research, published in the Journal of Pathology, said that better classification of these tumours could lead to more personalised management of the diseases, linked with their origin.

According to the researchers, the rare form of pancreatic cancer known as a mucinous cyst has strong similarities with another mucinous cancer which affects the ovaries. Both diseases, which have no direct relationship with one another, affect young women between 30 and 40, and are usually treated by surgery. In 15% of cases, however, the cyst breaks before surgery, giving rise to metastases which are highly resistant to chemotherapy.

The scientists realised that the organs were only close together during embryogenesis, when primordial germ cells make a migration through the human body between four and six weeks into the pregnancy. It is now thought some of the germ cells are deposited unexpectedly in the wrong organs during pregnancy, expressing themselves later as cancer.

The researchers developed a transcriptomic profile identifying gene expression levels in a tissue, looking at primordial germ cells at six, seven, 11, 16 and 17 weeks of pregnancy. Using data from both the pancreas and the ovary, they compared healthy tissues, mucinous tumours and other types of tumours, and found that in both pancreas and ovary the transcriptomic profile of the mucinous tumour is a long way from the supposed tissue of origin, but very close to the primordial germ cells.

While the findings will not lead to a change in surgical management of patients, they could lead to refinement of chemotherapy protocols, Dr Intidhar Labidi-Galy, one of the researchers at UNIGE and a physician at HUG, said. “By linking them to other cancers, we hope to identify treatments that would be effective. For each mutation, what is the best treatment? We are here at the heart of personalized oncology: knowing your enemy in every detail makes it easier to fight him.”