Oxygen levels in tumors affect response to treatment

tumors with lower levels of oxygen -- known as hypoxia -- often respond less well to radiation therapy. There are several agents that can be given to patients before radiotherapy to reduce hypoxia, but these are not given as standard. Being able to measure how well-oxygenated an individual's tumor is would give doctors a valuable way of identifying which patients might benefit from treatment with hypoxia reducing agents before radiotherapy.

Hypoxia has previously been investigated by looking at the expression of certain genes, and Manchester researchers have come up with a genetic profile for tumors that should indicate the overall level of oxygenation.

Researchers at The University of Manchester, part of the Manchester Cancer Research Centre, carried out the study in patients diagnosed with cancer of the bladder and larynx. These patients subsequently underwent either standard radiotherapy or radiotherapy with the addition of two agents which in combination are known to increase oxygenation: nicotinamide and carbogen.

The team tested patients' tumor samples for 26 genes in order to classify them as more or less hypoxic, and then analyzed whether this hypoxia score related to the results of treatment.

"Our goal is to find ways of predicting how patients will respond to different treatments. Future cancer treatments will be personalized so that patients get the best therapy for their tumor." said Professor Catharine West, who led the research. "Personalizing therapy will not only increase the number of people surviving cancer but also decrease side-effects, as patients would be spared from having treatments that are unlikely to work in their tumor."

A paper recently published in Clinical Cancer Research describes how the group found that for laryngeal tumors, those classed as more hypoxic saw a significant benefit from receiving additional agents as well as radiation therapy. However, in bladder cancer, patients with more hypoxic tumors did not benefit from adding extra agents.

Professor West added: "We will now test how the hypoxia score works in the clinic in a trial starting in December in patients with head and neck cancer. I have studied ways of measuring hypoxia in tumors for many years so this is a very exciting finding that could help us optimize how we use radiotherapy to get the best outcome for patients."