Diagnostic accuracy of computed tomography in patients with non-specific symptoms of cancer referred directly from general practice: a retrospective follow-up study

BACKGROUND: The urgent-referral Cancer Patient Pathway for Non-Specific Symptoms and Signs of Cancer (NSSC-CPP) was introduced in Denmark in 2012 to reduce delays in cancer diagnoses. In Region Zealand, it includes direct referral from GPs to contrast-enhanced computed tomography of thorax, abdomen, and pelvis (ceCT-TAP). In 2013, the NSSC-CPP cancer prevalence was 20%, but easy access to computed tomography (CT) may change referral patterns.

AIM: To examine cancer prevalence, diagnostic accuracy of ceCT-TAP, and changes in NSSC-CPP referral patterns.

DESIGN AND SETTING: Retrospective cohort study conducted in Region Zealand, Denmark.

METHOD: We included patients with non-specific symptoms or signs of cancer who were referred by GPs between 1 July and 31 December 2019. Primary endpoints were cancer prevalence and diagnostic accuracy of ceCT-TAP. Secondary endpoints were cancer types, referral trends between 2012 and 2019, and prevalence of GP-reported symptoms and clinical findings. Patients were followed up until cancer diagnosis or up to 12 months after ceCT-TAP, whichever came first.

RESULTS: In total, 729 referrals were recorded, a five-fold increase compared with 140 referrals in the same period of 2013. Malignancy was diagnosed in 95 (13%) patients. Twelve patients had a false-negative ceCT-TAP result, yielding a negative likelihood ratio (LR) for malignancy of 0.15.

CONCLUSION: Despite a five-fold increase in GP referrals for ceCT-TAP since 2012, it remains an important diagnostic tool, identifying malignancy in one in seven patients. However, as the LR- was >0.10, a normal ceCT-TAP does not convincingly rule out cancer and should not stand alone as the only decision-support tool.