Earlier diagnosis of symptomatic cancer is one of the main ways to improve cancer survival. Leukaemia is no exception to this, particularly as haematological cancers as a whole have a higher than average chance of emergency admission, with additional mortality from the complication that precipitated the emergency.1 Overall, there are nearly 10 000 new leukaemia diagnoses annually in the UK, equating to approximately one new diagnosis per general practice each year.2 The lifetime chance of developing leukaemia is roughly 1 in 70.3 There are few specific risk factors other than increasing age, though childhood acute leukaemias remain important, especially in children with Down’s syndrome and neurofibromatosis, who have an increased risk.4 The distinction between acute and chronic leukaemias is increasingly blurred, as genome sequencing allows much more precise subdiagnosis than before.5
In the traditionally called ‘acute’ leukaemias, where myelocytic or lymphocytic cells are proliferating rapidly, rapid diagnosis can avert or ameliorate the complications from bone marrow collapse, such as anaemia, bleeding, or overwhelming infection. In chronic leukaemias, there are now several treatments that can slow — or even halt — disease progression, reducing symptoms and increasing survival.6 Not all chronic leukaemias require immediate treatment though all require individualised assessment, based on the white cell count, symptomatology, and some genetic factors, which are used to identify those with most to benefit from treatment.7 Survival is slowly improving, though largely as a consequence of treatment advances rather than diagnostic ones.8
Challenges in diagnostic testing for leukaemia
The symptoms of chronic and acute leukaemias in primary care have both overlapping and distinct features.9 Most symptoms are non-specific, such as fatigue, night sweats, and joint pain, each with a very low risk of leukaemia, well below a positive predictive value of 1%. In a hospital series of childhood acute lymphoblastic leukaemia, bone and joint pain was a relatively common presenting feature alongside fever, hepatosplenomegaly, and lymphadenopathy.10 A primary care study reported similar features, though that work examined all childhood cancers, with only 29% being leukaemia.11 These symptoms explain why many adult leukaemia diagnoses are unexpected findings: usually the GP is investigating patients with vague ill health, with cancer only one of many possible causes. In many cases, the abnormal full blood count result is reported to the GP after the result has been seen by a haematologist, and specialist advice has been included with the result.
In theory, diagnostic testing for leukaemia is easy: nearly all patients have an abnormal full blood count — a test all primary care practices should be able to offer. Indeed, leukaemia is one of the very few cancers where the definitive diagnostic test is in the GP’s surgery. Therefore, the reason for delays in diagnosis is the selection of who to test rather than not knowing how to test, plus the ability to perform the test in a timely manner. Delays in leukaemia diagnosis do occur: Leukaemia UK, the main UK charity, and Leukaemia Care conducted a patient survey, with only one-third of leukaemia patients reporting receiving a blood test following their first consultation about their symptoms.2 This survey included patients with acute leukaemias, with almost a quarter reporting delays of up to 4 months to get a blood test after their first presentation to the GP with symptoms.
The National Institute for Health and Care Excellence (NICE) NG12 guidelines for suspected cancer recommend that everyone presenting with leukaemia symptoms should be offered an urgent full blood count within 48 hours, though at the time of compiling the guidance there was no primary care evidence to underpin this recommendation.12 Most patients with these symptoms receive a full blood count with much less urgency, as the above charity survey makes clear. In part, this is because access to primary care is problematic in some areas of the country, and access to phlebotomy similarly patchy. Thus, some clinicians are simply unable to offer blood tests to patients presenting with the symptoms as recommended by NICE.
The solution
However, what can be viewed as a problem can also be seen as a solution. Given there is a test that should be easily accessible in primary care, the solution is in improving (or restoring) ubiquitous primary care phlebotomy, allowing a modest increase in testing. At the same time, it needs to be remembered that there are many reasons to do a primary care full blood count — indeed nearly a quarter of the adult population have one in any one year13 — and it is rare for the clinician to be specifically considering leukaemia when ordering a full blood count. Education of patients, GPs, and other healthcare professionals, such as pharmacists, in the symptoms of leukaemia may be useful, but perhaps more useful is harnessing the experience of GPs in recognising the ill patient, and removing barriers to what is a simple investigation. Much effort has gone into establishing rapid diagnostic centres and community diagnostic hubs. These help in identifying cancer, though require relatively expensive technology and staffing. When it comes to leukaemia, no additional fancy technology is needed. Full blood counts are inexpensive, costing the NHS around £9 each. This is considerably cheaper than diagnostic tests for other cancers. Low-technology solutions are easy to ignore, but the benefits of ubiquitous and timely phlebotomy shouldn’t be lost in the drive to improve cancer outcomes.
Acknowledgments
Thanks to Leukaemia Care and Leukaemia UK, who alerted me to the issue, plus Sarah Price and Eve Kingston who helped me to clarify my thinking.
Notes
Provenance
Commissioned; not externally peer reviewed.
Competing interests
The author has declared no competing interests.
- © British Journal of General Practice 2024
