October 25, 2015

Safer and more comfortable breast cancer screening on the horizon

Breast cancer is the fourth most common cause of death from cancer in Australia – and the second most common cancer in women. And while breast cancer awareness is improving, the rate at which women are screened in Australia falls short of many other developed countries.

Attending a breast screening is daunting: there is much pain associated with the current 2D mammography, the radiation dose is high and the diagnostic accuracy low.

Dr Timur Gureyev, University of Melbourne, is working on maximising the benefits and minimising the harms of breast screening technology. “Up to 76 per cent of women experience pain or discomfort during and up to four days after a mammographic procedure,” explains Dr Gureyev. “Couple this with a 30 per cent chance of cancers being missed (false negatives) and many women receiving false positives, it is little wonder Australian attendance rates do not compare favourably to elsewhere.”

One of the other concerns raised with regular screening is the high radiation dose. Some studies even say the harm from screening could outweigh the benefit. This is due to breast tissue being recognised as the most radiosensitive tissue in the body; it is most likely to respond adversely to radiation.

Dr Gureyev and a group of colleagues have been working on an alternative pain free 3D X-ray breast imaging technology with lower radiation doses and increased sensitivity and specificity.

“The project will result in the establishment of a new technique to detect breast cancer more effectively, at significantly reduced radiation dose and minimum patient discomfort compared with current techniques,” says Dr Gureyev. “Our proposal to the National Breast Cancer Foundation will be a multinational and multi-institute project with the world’s first patient trial of inline phase-contrast computed tomography (PCT).”

At least five world-expert radiologists will use the new image evaluation platform and assign diagnostic scores to the PCT mammograms. They will then compare the relative sensitivity and specificity of the same tissue samples screened with the previous standard digital mammograms (and any available tomosynthesis images). From this evaluation study, evidence to develop a comprehensive and formal clinical trial of PCT mammography will be developed. During the trial, involving 100 women, patient satisfaction will be gauged through customer surveys. “The bulk of the work will be performed in Australia using the Imaging and Medical beamline at the Australia Synchrotron,” says Dr Gureyev.

The technique of PCT mammography requires a spatially coherent X-ray beam with sufficient intensity to perform CT scans within a reasonable time. This is currently possible only at synchrotrons. Imaging and Medical Beamline (IMBL) at the Australian Synchrotron in Clayton, Victoria, has provisions for PCT imaging with variable sample-to-detector distances which can be extended to several meters, as well as the largest coherent beam in the world allowing whole-chest imaging without the need for scanning. Due to the tunability of the synchrotron radiation sources, it is also possible to perform pilot experiments at several different X-ray energies.

Finding breast cancer early before any symptoms are noticed, and when treatment is most likely to be successful, gives women the best chance of survival. And regular breast screens – every two years as recommended by the Cancer Council of Australia – is the best way to find cancer early.

“By improving the safety and comfort levels during these procedures we hope to raise attendance from less than 55 per cent to close to 100 per cent,” says Dr Gureyev. “Reducing compression and dosage should, in theory, have a knock on effect for the numbers of early diagnosis.”

In the next couple of years, this project will likely develop in two related streams. In the first stream, we will be working, in close collaboration with several groups in Australia and Europe, towards the world-first live patient trial of the synchrotron-based PCT mammography. Initially, a trial involving up to 100 volunteers will likely take place within the next 12-24 months at the Elettra synchrotron in Trieste, Italy. This will be followed by a further trial at the Australian Synchrotron. In the second stream, we will be working primarily with colleagues from Monash University, Monash Health, La Trobe University and the Australian Synchrotron on the development of a PCT scanner that could be used in, or next to, the operating theatre for rapid 3D imaging of excised tissue samples during breast cancer surgeries. The main use of such an instrument will be high-quality visualisation of tumour boundaries within the excised specimen, in order to verify that the whole of the tumour has been removed.

“We know that breast cancer can be very aggressive, with the success of treatment depending heavily on early detection – currently the most important factor for reducing the morbidity and mortality of the patients,” Dr Gureyev concludes.