Prof. Gareth Jenkins
Thu 27th Oct
Presidents' Invitation Lecture, Thursday 27 October 2016
Prof. Gareth Jenkins, 'Blood tests for cancer diagnosis
Prof. Gareth Jenkins leads a multi-disciplinary team in Swansea University Medicine School investigating the potential of blood tests to diagnose human cancers at an early stage. At the start of his talk, originally given at a session of the British Science Festival held in Swansea in September, he paid tribute to the other members of his team, especially Dr Hassan Haboubi, who had been released from his medical training to pursue a PhD on the project.
Prof. Jenkins started from two propositions: first, that cancer, which will affect one in two of the current UK population, is a painful, often fatal disease for the patient and a highly distressing one for the family, and we should do our very best to try to prevent or overcome it, and second, that the key to effective cancer care at present is to diagnose it as early as possible, at a time when it is most treatable.
The team concentrated on a particular form of the disease, oesophageal cancer. At present the life expectancy of a person with oesophageal cancer is low – only 15% of patients live for more than five years. And the current principal means of diagnosis, endoscopy, is expensive, invasive and incapable of being scaled up to treat larger populations.
The team’s new, alternative approach is to analyse blood samples, using flow cytometry, from three groups of people: those known to have the cancer, those thought to be ‘at risk’, and those unaffected. The results from each group are compared, to identify differences. This method of blood sampling and analysis Prof. Jenkins termed ‘liquid biopsy’. It doesn’t aim to detect direct signs of the cancer, but rather a surrogate for them, a kind of ‘cancer smoke detector’, namely traces of DNA mutations occurring in red blood cells as a result of the cancer’s presence. The team tested 300 people. In patients with the disease there proved to be a much higher incidence of ‘naked’ cells, lacking the proteins that normally adhere to red blood cells via ‘velcro’ pads on the cell walls. These patients have an average of 43 mutations per million, as opposed to an average of 6.2 per million in the healthy population. The blood test succeeded in identifying 80% of the people with the disease, and could also point to those who may be at risk from developing it.
Characteristics of the patient groups were analysed to shed light on the factors influencing the presence of oesophageal cancer. Increasing age, unsurprisingly, influenced the incidence of the disease. A less expected finding was that more women than men developed it. Quality of diet had a major influence, and regular aspirin intake reduced the risk of the cancer.
Prof. Jenkins suggested that the project, and others like it, could lead the way to the use of simple and inexpensive blood tests to diagnose oesophageal cancer, and, by extension, other types of cancer. These tests might, at some time in the future, be administered, and their results analysed, in the GP’s surgery, with anomalous results being referred to hospital for more detailed examination. The outcome would be much earlier detection and treatment of cancers.
Prof. Jenkins responded to many questions from members of the audience.
He referred to blood test studies investigating other cancers. It was unclear from the few published so far whether in future specific tests could be matched with specific cancers, or whether the tests would apply equally to a variety of different types of cancer. It was likely that some would prove ineffective. But the hope was that a battery of different tests would be able to detect different cancers, all at an early stage.
In general environmental factors are powerful influences on the incidence of cancer. Social and economic deprivation and their effects probably account for higher rates of cancer in Wales than in other parts of the UK. Heredity, though, plays a large part in some types, like breast cancer. One questioner wondered whether, granted that they are now commoner today because on average we live longer than our ancestors, cancers have been part of our experience since the beginning of human evolution.