Symptomatic diagnosis of cancer of the brain and central nervous system in primary care: a systematic review

Background: We performed a systematic review of diagnostic studies of symptomatic patients in primary care to quantify the risk of brain/central nervous system (CNS) cancer in patients presenting in primary care with symptoms that may indicate brain/CNS cancer.

Objective: To quantify the risk of brain/CNS cancer in symptomatic patients presenting in primary care.

Methods: We searched Medline, Premedline, Embase, the Cochrane Library, Web of Science and ISI Proceedings (1980 to August 2014) and PsychInfo (1980 to February 2013) for diagnostic studies of symptomatic adult patients in primary care. Study quality was assessed using QUADAS-II and data were extracted to calculate the positive predictive values (PPVs) of symptoms, singly or in combination, for brain/CNS cancer.

Results: Six studies with 159938 patients were included. The PPVs of single symptoms were very low with only 'new-onset seizure' being above 1% in patients aged 18 years and above, rising to 2.3% in patients aged 60-69 years. In patients aged 15-24 years, the PPVs for the individual symptoms were also very low, with the highest, also for seizure, being 0.024%, similar to that in children aged 0-14 years of 0.02%. For symptom combinations, none of the PPVs were above 0.39%.

Conclusions: All the symptoms of brain tumours are individually low risk, apart from new-onset epilepsy. This provides a real diagnostic problem, as brain tumours have all the expected features seen with cancer diagnostic delay, with high proportions presenting as an emergency and having had multiple primary care consultations before referral, and the prognosis is poor. Improving these metrics can only be done by liberalizing investigation, although the health economics of that strategy is undetermined.