Implementing Risk-Based Triage for Ovarian Cancer Detection in UK Primary Care Using Ovatools: A Modelling Study

OBJECTIVES: Primary care guidelines in England recommend serum cancer antigen 125 (CA125) testing in women with possible ovarian cancer symptoms, followed by pelvic ultrasound (US) if CA125≥35u/ml. However, ovarian cancer risk varies markedly by CA125 level and age. The Ovatools model, which incorporates age and CA125 level, predicts ovarian cancer risk to inform further investigation. We examined the effect of implementing Ovatools in UK primary care.

METHODS: Women from the Clinical Practice Research Datalink (CPRD) with CA125 test or US scan+relevant symptoms between 2013-2017 were included. A decision model combining a decision tree and a Markov model was used to assess the impact of Ovatools on cancer outcomes in two primary care pathways (A: CA125+US or B: US only). Pathway A, where patients were referred based on sequential abnormal CA125 then US, was compared with the augmented pathway based on Ovatools risk: discharge if <1%; check US if 1-3%; secondary care referral if ≥3%. Pathway B, where patients were referred based on abnormal US, was compared with an augmented pathway with use of Ovatools risk ≥3% to check negative US results.

RESULTS: 416,004 patients were included. For augmented Pathway A, the model predicted that the Ovatools approach detected further 180 originally late-stage ovarian cancer cases, shifting 30 from late to early stage (0.14 life year and 0.11 QALYs gained per ovarian cancer patient). For augmented Pathway B, the Ovatools approach detected further 351 originally late-stage cases, shifting 58 from late to early stage (0.28 life year and 0.22 QALYs gained per ovarian cancer patient). Ethnic minorities, socioeconomically disadvantaged and those aged 50-70 benefited more. However, the Ovatools approaches increased unnecessary referrals.

CONCLUSIONS: Implementing the Ovatools in UK primary care could improve survival and quality of life for ovarian cancer patients. Further work is needed to examine costs' implications.