Thrombocytosis has an 11.6% positive predictive value for cancer in men and 6.2% in women, according to research published in the British Journal of General Practice (BJGP).
This increases to 18.1% and 10.1% respectively if a second raised platelet count is recorded within six months, the researchers added.
They said the findings ‘strongly suggest’ that cancer should be suspected in patients showing thrombocytosis, adding that if only a conservative 5% of cancer patients have thrombocytosis before diagnosis, then a third of them could have their diagnosis expedited by at least three months.
This equates to at least 5,500 earlier diagnoses annually, according to the study, which looked at over 40,000 patients aged over 40.
The risk factors ‘well exceed’ the NICE-mandated threshold of 3% risk to warrant referral for suspected cancer, the researcher said.
RCGP chair Professor Helen Stokes-Lampard said: ‘Timely diagnosis of cancer is key to ensuring our patients get the treatment and support they need, so any medical advances to support this and increase our understanding of the disease, should be welcomed.
'And as new research is published, it is important that it is reviewed, and if found to be robust, is taken on board and that guidelines for healthcare professionals are subsequently updated.
‘This research finding is interesting and builds on existing data about high platelet counts. Platelet counts are measured as part of a "full blood count" test which is a routinely available blood test for GPs.
‘But it remains important that GPs have access to other appropriate diagnostic tests in the community – including emerging tests and imaging techniques – as this would be of real benefit for our patients, and currently we have one of the lowest access rates to diagnostic tests in Europe.’