PC4 Podcast – Ovarian cancer and the use of CA125 in primary care

GP and CanTest Clinical Research Fellow Dr Garth Funston, based at the University of Cambridge, talks about his current PhD research with Dr Kristi Milley from the Primary Care Collaborative Cancer Clinical Trials Group (PC4) for a Research Roundup podcast recorded at the 2019 Cancer and Primary Care Research International Network (Ca-PRI) Conference held in Toronto in May.

In the podcast, Garth discusses his work evaluating tests and tools to diagnose ovarian cancer with a specific focus on biomarker CA125. He also talks about his use of big data to evaluate and improve the performance of cancer antigen 125 (CA125) biomarker as a test for the diagnosis of ovarian cancer in primary care. There has been a large body of research on CA125 related to screening in secondary care settings to monitor for relapse. However, among patients presenting to primary care with symptoms, little work has been done to evaluate and validate the use of CA125.

Ovarian cancer is difficult to diagnose in a primary care setting due to its rarity – in the UK a GP will see an average of one case every five years. Furthermore, Garth notes that many of the symptoms of ovarian cancer are not unique, resulting in misdiagnosis as a more common illness. Although conditions other than ovarian cancer can cause an increase in CA125, he believes that it remains the best tool we currently have for early identification of ovarian cancer.

Garth provides an overview of the datasets he is using in his research – the Clinical Practice Research Datalink and the National Cancer Registration and Analysis Service. In working with this data, his research has shown that a fifth of patients with ovarian cancer have a normal level of CA125 when tested within a year prior to diagnosis. Furthermore, the average diagnosis interval was much longer for those who had a normal level of CA125 compared to those with elevated levels (79 days versus 34 days, respectively). However, most patients were still diagnosed in the early stages of onset.

During the Ca-PRI Conference, Garth delivered a presentation titled ‘The association between CA125 level, diagnostic interval and stage at diagnosis in ovarian cancer: an analysis of CPRD and NCRAS data’ and has published an article on associated research in the journal Advances in Therapy; ‘Recognizing gynecological cancer in primary care: Risk factors, red flags, and referrals‘.

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