Clinical Trial Service Unit and Epidemiological Studies Unit ("CTSU")

The work of the CTSU chiefly involves studies of the and treatment of cancer and other major chronic diseases (such as heart attack and stroke).

Observational epidemiology
When important causes of disease are to be assessed, the effects of those causes are sometimes so extreme that the cause and effect relationships can be reliably inferred from purely observational studies. But, even so such studies need to be of sufficiently large scale to be able to determine the strength of such associations appropriately reliably. Over the past few years there has been increasingly clear realisation (in large part due to the work of the CTSU) of approximately how great the future epidemic of deaths due to tobacco will in developing countries. If current smoking patterns persist, world-wide deaths from tobacco will increase from about 4 million/year at present to about 10 million/year by the time the children of today reach middle age. The CTSU has established, with the World Health Organization, a long-term collaboration between many large studies of smoking and death to monitor the development of the world-wide epidemic of tobacco-related death and disability.

Large-scale randomised evidence
Unfortunately, when assessing possible improvements in the treatment of some disease, there may well be, at best, only a moderate improvement in outcome. Just a moderate improvement in a common disease might, however, save thousands of lives a year (and prevent much disability) so it is important not to get wrong answers. The best way to obtain results about moderate treatment effects is by getting large-randomised evidence.

As one way of achieving such evidence, the CTSU has established the use of collaborative systematic overviews ("meta-analyses") of several randomised trials that have addressed much the same question. In breast cancer, for example, the CTSU established the Early Breast Cancer Trialists' Collaborative Group (EBCTCG), bringing together results from all randomised trials comparing different treatments for "early" breast cancer. This showed clearly that a few years of tamoxifen (which is a relatively inexpensive and non-toxic hormonal treatment) can significantly improve the ten-year survival, as can multiple-drug chemotherapy, and the resulting change in medical practice has led to the avoidance of tens of thousands of deaths each year. CTSU is also co-ordinating world-wide overviews of all leukaemia trials, and of colorectal and prostate cancer trials.

The CTSU also established the use of very large simple randomised trials ("mega-trials"), typically involving tens of thousands of patients, to assess reliably the effects of widely practicable treatments on mortality and on major morbidity in common diseases. Currently, the CTSU is conducting a very large international trial of the effects of giving five extra years of tamoxifen to breast cancer patients who have already been on the drug for about five years; several major randomised trials in China of the treatment of colorectal and breast cancer; and a large study of adjuvant chemotherapy after surgery for colorectal cancer. CTSU is also responsible for all of the Medical Research Council leukaemia trials.

World-wide Collaboration
Such large-scale research cannot be conducted by individual scientists, and the emphasis at the CTSU is on international collaboration.