A total of 80% of practices are unfairly labelled as ‘poorly performing’ in the annual publication of urgent cancer referrals, the study found.
NHS England annually publishes the percentage of cancer cases that were diagnosed after urgent two-week referral, and ranks GP practices according to this cancer detection rate.
But researchers at the University of Aberdeen say the annual diagnosis rates are ‘misleading’ and should be replaced.
The GPC has previously said that the cancer ratings were ‘simplistic’ and underlying causes of low cancer referrals needed to be better understood.
The British Journal of Cancer study looked at 8,303 practices in England over four years.
Low numbers of urgent suspected cancer referrals are often linked to poor GP performance, but the researchers say it is down to differences in the types of cancer being presented.
Some cancers can be more difficult to diagnose, such as ovarian cancer, which has non-specific symptoms, they said.
Small and average-sized practices are at a disadvantage because of the low overall number of cancer cases they see in a year, the study found.
‘An average sized GP practice of 6,000 patients and four GPs will have less than 30 new cancer cases each year, which is actually a small number for making such big comparisons,’ said lead author Dr Peter Murchie, a senior lecturer in primary care from the University of Aberdeen.
‘With only one year’s data, we estimate that four out of every five average-sized practices which are reported as performing poorly will be incorrectly labelled,’ Dr Murchie said.
‘Measures from single years of data are misleading and should not be publicly reported.’
Examining data over four years should make the data more reliable, the researchers believe.
Dr Richard Roope, Cancer Research UK’s GP expert, said: ‘Cancer isn’t always easy for GPs to identify, and this research highlights the complexities involved and why sets of data don’t always give the full picture.’