Reducing ovarian cancer mortality through screening: an impossible dream?
The history of screening tests for ovarian cancer is not good. Two huge trials; the UKCTOCS with more than 200,000 recruits over 20 years and the PLCO trial with more than 3 million pathology samples showed no benefit in terms of survival from ovarian cancer.
This article addresses the stages of ovarian cancer using an alternative approach called the clinical continuum, which divides cancer into 3 phases, no disease, pre-clinical (detectable disease), and clinical (overt cancer).
Obviously for a screening test to be effective, cancer needs to be detected before the clinical phase. However, ovarian cancer is unlike other cancer in that the precursor occurs in the fallopian tube and there is an argument to say that, by the time ovarian cancer has occurred, it is always advanced and metastatic. This time interval between initial and advanced disease has been called, “the sojourn”. A short sojourn implies that screening tests are unlikely to be helpful.
Any ovarian screening test would have to demonstrate cost-effectiveness. Because of the short sojourn, screening would need to be at less than yearly intervals. Also, the authors note the continual decline in the incidence of ovarian cancer, over the last 100 years. These factors make the allocation of scarce resources to ovarian cancer screening unlikely.
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