Expert opinion: New ideas in cancer therapy - oxygen bubble drinks
One of the major difficulties that tumours encounter as they grow is a lack of oxygen. This is because they often grow faster than the surrounding blood vessels can adapt to them, and as oxygen that comes out of the blood can only penetrate 3 to 4 layers of cells, the core of the tumour may lack sufficient oxygen, a state known as hypoxia.
This slows cell growth and can lead to the cells in the tumour core dying, which would be good news if the story ended here. However, many hypoxic cells can enter a dormant state, slowing down and changing their metabolism, biding their time until more oxygen becomes available. These cells are particularly troublesome as they are often more resistant to chemotherapy, in part because of their dormant state, but also because they are a relatively long distance from the nearest blood vessel and therefore receive less of the anticancer drug.
Researchers from Oxford and Ulster are now developing a drink, rich in oxygen micro-bubbles, that could deliver oxygen to tumours. These researchers have previously shown that injecting oxygen into mice with cancer and then giving them chemotherapy leads to more successful treatments, and a recent report on the BBC news website describes how they have also treated mice with drinks enriched with oxygen microbubbles.
Although the preliminary experiments sound as though they are encouraging, this is unfortunately at a very early stage to discuss this research, and significantly more work is needed before it is clear whether these drinks should be trialled in humans. In addition, a strategy that involves deliberately bringing cancer cells out of a dormant state would seem inherently risky: it is assumed that this will make them far more sensitive to chemotherapy, but what if it doesn’t? It is this part of the problem that is hard to assess in mice as experimental tumours lack the complexity and variability of human tumours. None the less, this is an interesting idea and I look forward to reading the published study.