Ovarian cancer often goes undetected for a long time. In seven out of 10 patients, the tumour has already formed secondary tumours in the abdominal cavity at the time of diagnosis.

These metastases are particularly common in a tissue called the omentum, also known as the peritoneal apron.

This organ is located in front of the intestine, performs protective and immune functions, and harbours fat cells.

“In advanced ovarian cancer, the question arises as to whether, in addition to the visible tumours and metastases, the omentum should also be completely removed as a preventive measure in order to reduce the recurrence of tumours,” explains Dr. Francis Jacob from the Department of Biomedicine at the University of Basel and the University Hospital Basel.

Cell atlas of healthy and diseased states

To answer this question, the team led by Jacob and Professor Viola Heinzelmann-Schwarz analysed 36 tissue samples from 15 patients, taken from different parts of the omentum.

Some of the samples came from ovarian cancer patients who already had secondary tumours in this organ, while some of the samples came from patients whose omentum was cancer-free but were suffering from other types of cancer.

The researchers analysed precisely which cells were present in the samples and created a cell atlas of the omentum in a diseased and a healthy state.

The results indicated that the healthy omentum has a balanced cell composition, which means that the same cells are present in equal quantities at all the examined sites. These primarily include surface cells, mesenchymal stem cells and immune memory cells.

Restructuring of the entire organ

In the case of ovarian cancer patients, however, it was found that the cancer transforms the omentum into an environment that favours the spread of tumours: more immune cells were present in the tissue samples, including in particular the cell types that dampen the immune system’s ability to attack tumour cells and thus help the cancer.

There were also fewer surface and stem cells present in these omentum samples. It is possible that these transform into other cell types that also create a favourable environment for metastases.

“A key finding is that even tissue far from the tumour undergoes changes in its composition and already contains individual tumour cells. When cancer cells migrate into the omentum, they hijack the entire organ,” explains Jacob.

This results in the loss of the normal tissue structure and regenerative capacity of the omentum. Based on these findings, it may be more beneficial to remove more of the omentum during surgery to remove the tumours, rather than just the visibly diseased part.

This could potentially reduce the number of times the cancer returns. However, Jacob emphasises that whether this approach actually leads to a better prognosis must be verified in a follow-up clinical study.

Article: Ovarian cancer metastasis to the human omentum disrupts organ homeostasis and induces fundamental tissue reprogramming

Source: University of Basel