Liquid biopsy in the diagnosis of ovarian cancer – a compilation of scientific literature

Summary

The aim of the project was to compile the current state of knowledge on liquid biopsy-based diagnosis of ovarian cancer. Ovarian cancer is a serious disease with a high mortality rate. Prognosis is largely dependent on early diagnosis, which is often difficult as symptoms are initially both vague and elusive.

Currently, there is no tumor-marker with sufficient accuracy that can be used alone for diagnosis. Furthermore, unlike the diagnosis of other solid tumors, such as breast and lung cancer, needly biopsy is not performed in suspected localized ovarian cancer, as the risk of spread is high and thus worsens the prognosis. This distinguishes ovarian cancer from many other malignant conditions with solid tumors and enhances the need for a new form of diagnosis. Today the confirming microscopic diagnosis is obtained from the examination of surgically removed suspected tissue.

Liquid biopsies are obtained from any bodily fluid, but most often blood. The fluid could be looked upon as a carrier of dissolved substances originating from a suspected tumor. The analytical methods can measure very small concentrations of tumor markers (e.g. genetic material, proteins, etc.). Theoretically, the method could diagnose accurately and early and without any risk to the patient. Pre-operative needle biopsy of suspected localized ovarian cysts is avoided. Samples from asymptomatic women, women with unclear symptoms or women at increased risk of the disease can readily be gathered in different healthcare settings.

Based on published systematic reviews, our exploratory literature search between 2012 and 2023 revealed insufficient well-designed primary studies to conduct our own systematic review. We have not been able to evaluate the overall diagnostic accuracy in a scientifically reliably way for different types of analyses of liquid biopsies as published studies have shown major variations in terms of population at risk, control groups, study design, what is analyzed and analytical methods.
More and larger well-designed studies are needed before the different related methods can be evaluated. Thus, liquid biopsies are not yet ready for clinical diagnosis of ovarian cancer.