Diagnostic accuracy of CT in patients with non-specific symptoms of cancer referred directly to CT 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 delay in cancer diagnosis. In the Zealand region, it includes direct referral from GPs to contrast-enhanced CT of thorax, abdomen, and pelvis (ceCT-TAP). In 2013, the NSSC-CPP cancer prevalence was 20%, but easy access to 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 from the Zealand region of Denmark.

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

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

CONCLUSION: Despite a fivefold 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 negative likelihood ratio was>0.10, a normal ceCT-TAP does not convincingly rule out cancer and should not stand alone as the only decision-support tool.