'Virtual biopsies' could replace tissue biopsies for ovarian cancer

A new scanning technique has the potential to replace tissue biopsies for complicated ovarian cancer patients. 

Cancer researchers at the University of Cambridge and Cancer Research UK (CRUK) have repurposed a combined imaging technique that could allow doctors to improve tissue sampling of ovarian tumours, leading to fewer invasive procedures that are required to identify the optimum treatment. Using the combination of computed tomography (CT) and ultrasound imaging scanning, the researchers wanted to improve the diagnosis of high-grade serous ovarian cancer (HGSOC) which has proved difficult to assess from single biopsies. 

'This study provides an important milestone towards precision tissue sampling,' said Professor Evis Sala from the Department of Radiology, co-lead of CRUK Cambridge Centre advanced cancer imaging programme. 

The most common type of ovarian cancer, HGSOC has been labelled the 'silent killer' as it is often asymptomatic at early stages, meaning tumours often progress to an advanced stage before they are diagnosed. They are more difficult to treat at this stage as advanced tumours often contain numerous cell lines with genetically distinct phenotypes (known as tumour habitats), creating a complex mosaic of cancer cells that respond differently to various therapeutics.

This is where the ovarian cancer researchers directed their focus. An emerging technique using a fusion of CT/ultrasound to target tumours that are undetectable with ultrasound alone had been established already for hepatic lesion imaging. However, this system had not been applied for biopsies in patients with HGSOC. 

In the study published in European Radiology, six patients with suspected HGSOC were given CT scans following identification of tumour habitats. These habitat maps and CT images were superimposed together onto live ultrasound images. Using a landmark system, the ultrasound scan was guided over the targeted biopsy areas and samples were collected for clinical diagnosis and research purposes. The results showed that the fusion accuracy (overlap of the tumour region) between the CT and ultrasound scans was good for larger pelvic tumours, although this was less so for the smaller metastases.

'Our study is a step forward to non-invasively unravel tumour heterogeneity by using standard-of-care CT-based tumour habitats for ultrasound-guided targeted biopsies.' said co-contributor Dr Lucian Beer. 

Although this novel technique has certainly opened the door for more CT/ultrasound fusion imaging to be explored, the sample size was small and two out of six patients yielded an inadequate sample.

'We will now be applying this method in a larger clinical study,' co-contributor Paula Martin-Gonzalez said.