Good morning on this first Monday of a new millennium. As weary bodies recover after the celebrations of the last week, thoughts begin to turn to self-improvement and that annual ritual - the New Year resolution.
Health usually features in these mental lists of self renewal. Lose weight, give up cigarettes, drink less and exercise more. Each one a very laudable aim - but will they actually improve your health?
Tomorrow we will examine the medical evidence to see whether diet and exercise make a difference in the prevention of various illnesses. Today, however, we start by looking at the medical equivalent of an MOT - going for a medical check up.
Doctors spend most of their working lives treating existing disease, but preventative medicine and screening are assuming greater importance as medicine moves from an era of major treatment breakthroughs to one in which the focus is increasingly on prevention.
So where does this leave the average consumer? Should you present yourself for annual health screening or not? To answer this question, we need to look at what we mean by medical screening. In the broadest sense, it could mean spending half a day being examined by a doctor and having a range of tests performed. Cardiographs, chest X-rays, a wide range of blood tests and a very detailed examination represent "casting a wide net".
This unfocused approach is popular and undoubtedly uncovers some previously undetected disease. However, there is no medical test that is 100 per cent accurate. False positives, in which a screening test suggests there is a problem when in fact there is not, cause both confusion and unnecessary anxiety. False negatives, where a test is reported as normal in the presence of disease, are clearly even more worrying. Unless a test is cheap, reliable and can easily be applied to a large population, then its use for medical screening is rather limited. So far, medicine has yet to come up with the perfect screening test.
There is an alternative approach. By tailoring the medical examination and tests to the individual, the screening process is immediately made more effective. For example, if the age, sex and family history of an individual are factored into the equation, then it becomes possible to undertake targeted screening. Better still, if we regard screening as a dynamic process, in which the tests are carried out over a period of time, we succeed in transforming a single snapshot into a series of pictures. This is the best way to approach health screening.
Cancer and heart disease account for almost 50 per cent of all deaths in the Republic each year. Osteoporosis is a common but preventable disease. How might screening help to reduce mortality and morbidity for each of these conditions ?
Bowel cancer
Colorectal cancer, to give it its full medical name, is the second commonest cancer in this country. Clearly, this is an incentive to pick up the disease at the earliest possible opportunity, especially as, if it is extensive when diagnosed, the five-year survival rate is a discouraging 3 per cent.
Patients at increased risk of bowel cancer include those with a family history of the disease and also people with long-standing inflammatory bowel disease. The importance of such factors can be seen from the statistics: with one close relative the lifetime risk of having colorectal cancer is 1:17, and with two close relatives the risk rises to greater than 1:10.
The research evidence suggests that if you have a mother, father, brother or sister with a history of bowel cancer, then you should be screened for the disease at an age 10 years younger than your affected relatives. In other words, if your family member is diagnosed with the disease at age 50, then you should begin a screening programme at age 40.
This involves having a regular colonoscopy, which is an examination of the bowel using a flexible telescope. It is performed by an experienced specialist gastroenterologist, who will decide, based on your particular history, how often this examination should be carried out. A colonoscopy costs approximately £200.
What about the rest of us? Clearly colorectal cancer is common in Ireland. Is there anything we can do?
The general population could be tested for the presence of blood in the faeces - which can indicate the presence of colorectal cancer. However, this test has a particularly high false positive rate due to the fact that blood detected in faeces can be due to causes other than bowel cancer. Studies in the UK and Denmark have demonstrated relatively modest reductions in bowel cancer mortality as a result of this type of general population screening.
Research is ongoing into the feasibility of once-off flexible sigmoidoscopy (an examination of the lower part of the bowel). The trials are being conducted on people aged between 50 and 60, and it remains to be seen how effective a preventative mechanism this turns out to be.
Technology holds out the prospect of a virtual colonoscopy. This is a high-tech MRI scan which allows the doctor to "see" inside the large bowel without the unpleasantness of inserting a tube into the patient. Virtual colonoscopy could well assume a key role in screening for colorectal cancer in the 21st century. Dietary changes can also help - we will explore this issue in tomorrow's page.
Breast cancer
The purpose of effective screening is to detect disease before it would normally come to the attention of health professionals. This allows the disease to be treated much earlier and the outcome improved. This is the aim of the new National Breast Screening Programme (Breast Check) which has just been launched. Every women between the ages of 50 and 64 will be offered the opportunity of having a mammogram, with the aim of picking up potential breast cancers.
The reason for restricting the programme to this age group is, firstly, that the incidence of breast cancer is highest in postmenopausal women and, secondly, experience in other European screening programmes has demonstrated a 20 per cent reduction in mortality using this age range. Emphasising the value of a dynamic rather that a "single shot" approach, women will be offered re-screening every two years. Breast Check will need at least 70 per cent of the target population to attend for mammography in order to achieve the optimal reduction in mortality.
This latter estimate underlines both the strengths and weaknesses of large population screening. The reduction in mortality is proven for the entire target group, but at the same time the individual benefit can be harder to quantify. With false positive tests a possibility, the creation of a group of "worried well" women is a potential problem, although it must be said that the Irish programme has made extensive provision - in terms of counselling and in the speedy further assessment of those women with positive mammograms - to minimise this. The programme should achieve a reduction within 10 years of one-fifth in the current 650 annual deaths from breast cancer.
For younger women with a family history of breast cancer, then it may be appropriate to start mammography at an earlier age. Certainly, if you have two close relatives with the disease, it is important to discuss this with your family doctor, so that an individualised screening programme can be organised for you. And for the rest of the female population, there are dietary measures that can be taken to minimise the chances of developing breast cancer. But, more of this in tomorrow's page.