The science and art of medicine

Last week’s BMJ cast yet further doubt on prostate specific antigen as a screening tool for prostate cancer (2009;339:b3572, b3537, b3601), and this week we warm to the theme of tumour markers and their limitations. The Clinical Review (doi:10.1136/bmj.b3527) and the Practice article on rational testing (doi:10.1136/bmj.b3111) make clear that tumour markers are a mixed bag, not to be used in screening, unhelpful for diagnosis in patients with non-specific symptoms, and best reserved for monitoring once a diagnosis has been made. Unfocused requests and inappropriate use of tumour markers cost health services around the world large sums of money. They provide false reassurance in some cases and cause unnecessary anxiety, investigations, and treatment in others.

The authors stress that in the right hands and in some conditions—notably germ cell tumours—tumour markers have an important role. And as options for cancer treatment improve, the next generation of predictive serum tests may identify patients most likely to benefit—the holy grail of personalised treatment already available to some extent in breast cancer care.

Also looking to the future, Menno de Jong and Rogier Sanders describe how recombinant technology may transform the way we produce flu vaccines (doi:10.1136/bmj.b4014). Using cell based platforms to produce subunits of the HA antigen would remove the need to grow vaccines in eggs, which is slow, unpredictable, difficult with some strains of virus, and (prosaically but obviously) limited by the supply of eggs. The ingenious flu virus can undergo both antigenic drift (through evolution of the HA protein) and antigenic shift (the development of pandemic strains). So it’s reassuring to hear from researchers in Mexico that last year’s seasonal flu vaccine seems to have provided some level of cross protection against H1N1, especially severe forms of the disease, during their recent epidemic (doi:10.1136/bmj.b3928).

Reassuring too that something as simple as vitamin D supplementation reduces falls in older people. Vitamin D improves muscle strength as well as bones, through a direct effect on vitamin D receptors in muscle. Trials have shown that in people at risk of vitamin D deficiency, supplementation improves strength, function, and balance in a dose related way. In their systematic review, H A Bischoff-Ferrari and colleagues identified eight randomised controlled trials of supplementation in people older than 65, and conclude that a dose of between 700 and 1000 IU per day reduces falls by about a fifth within two to five months of starting treatment (doi:10.1136/bmj.b3692). Lower doses don’t seem to be effective.

Elsewhere in this week’s journal we have a hymn to personal continuity in primary care (doi:10.1136/bmj.b3923). What Helen Richards means by this is being responsible for patients over an extended period of time, being the first point of contact in most episodes of illness, understanding the patient’s health in the context of their community, and coordinating care within a complex health system. By contrast with access to care, which is easy to measure and a vote winner, continuity is complex, hard to define, and even harder to quantify. In the current climate, this may mean it’s doomed.