Delayed cancer diagnosis unlikely to be due to poor medical practice

Poor professional performance is an unlikely cause of delays in referral for suspected cancer, argue researchers in The BMJ this week.

Instead, such delays largely reflect "limitations in scientific knowledge and in the organisation and delivery of healthcare." And they question government plans to rank general practices according to how promptly patients are referred to specialist services for suspected cancer.

Most patients who have cancer diagnosed after the onset of symptoms are referred after one or two GP consultations (80%), but a substantial minority (20%) have three or more consultations, explain Dr Georgios Lyratzopoulos at the University of Cambridge, and colleagues.

This number is often considered by policy makers and cancer charities to reflect an avoidable delay.

While multiple GP consultations prolong diagnostic intervals and may affect clinical outcomes and care experience, they largely reflect the diagnostic difficulty of different cancers and the need for initial investigations, argue the authors.

For example, cancers with fairly specific signs and symptoms (such as a palpable breast lump or a visible lesion) are easier to suspect and are less associated with multiple consultations than those with non-specific symptoms (such as back or abdominal pain).

They believe that diagnosis "may be swifter if facilitated by decision support interventions, better interactions between generalists and specialists, and easier access to diagnostics." But they stress that novel diagnostic tests will need to be developed for harder to suspect cancers. Such tests, however, "will need careful evaluation, ideally in pragmatic randomised controlled trials in primary care."

The authors highlight that in some patients, delays in diagnosis can also occur before patients present to doctors or after GPs have referred the patient. And they argue that policy initiatives focusing solely on professional performance are "unlikely to be effective."

Instead, they say future research and improvement strategies must recognise the role of variation in diagnostic difficulty across different cancers and organisational factors. They also advocate better information for the public, the media, and policy makers about the origins of prolonged intervals between presentation and diagnosis of cancer.