Irish scientists have made a breakthrough which could pave the way for new treatments for oesophageal cancer.

Around 400 people in Ireland are newly diagnosed with cancer of the oesophagus every year and this country currently has one of the highest rates of the disease in Europe.

Many patients receive radiotherapy and chemotherapy to shrink their tumour before they have surgery. While some patients respond very well to this treatment, the majority are resistant in varying degrees, which can delay surgery and worsen their overall prognosis.

As a result, resistance to radiotherapy is seen as a major problem when it comes to treatment of this disease.

However, according to a team of scientists at Trinity College Dublin (TCD), their findings may offer a means of fighting this type of resistance, paving the way for new treatment options.

They have discovered that a molecule called miR-17, which is lost from cancer stem cells, has a key role to play in driving the resistance of oesophageal tumours to radiotherapy.

Working with scientists from St James's Hospital, the Coombe Women and Infant's University Hospital and the University of Hull in the UK, the TCD team have shown that populations of tumour cells that have a bigger number of cancer stem cells form larger and more aggressive tumours.

These cancer stem cells are also more resistant to radiotherapy.

Until now, there has not been a way to determine which patients will respond well to radiotherapy, nor has there been a way to reduce radiotherapy resistance.

"This work is extremely important in understanding why tumours are inherently resistant to radiotherapy, and how they can acquire resistance. Our findings strongly suggest that it is the cancer stem cell population that we need to destroy if treatment is going to be effective in our oesophageal cancer patients," commented lead researcher, Dr Stephen Maher, of TCD.

He noted that until recently, cancer stem cells ‘were largely considered hypothetical, as there were no clear ways to identify and isolate them'.

"In this study, we spent a tremendous effort in identifying tumour cells that had biological markers normally characteristic of stem cells. Once we had identified these stem-like tumour cells, we isolated them and started to pick apart their biology," Dr Maher explained.

The research found that the population of cancer stem cells could be broken down further into smaller groups and these had distinct radiation sensitivity profiles.

A further analysis then revealed that levels of miR-17 - a powerful gene-regulating molecule - were particularly low in the cancer stem cells that were most resistant to radiation.

"Interestingly, in the lab we found that if we put a synthetic version of miR-17 into the resistant cells, they became more sensitive to radiation. Going forward, we could use synthetic miR-17 as an addition to radiotherapy to enhance its effectiveness in patients. This is a real possibility as a number of other synthetic miR-molecules are currently in clinical trials for treating other diseases," noted Dr Niamh Lynam-Lennon of TCD, who performed most of the work.

Details of these findings are published in the journal, Oncotarget.