New diagnostic tools aim to catch aggressive prostate cancer early
Two newly published studies are presenting novel diagnostic techniques to help catch the most aggressive forms of prostate cancer at an early stage. A University of East Anglia study presents an innovative way to measure gene expression in tumor samples and predict disease severity, while an Australian study details a new kind of imaging technique promising to detect metastasized prostate cancer with greater accuracy than ever before.
"Prostate cancer is the most common cancer in men in the UK," explains Colin Cooper, lead researcher on a new study from the University of East Anglia. "It usually develops slowly and the majority of cancers will not require treatment in a man's lifetime. However, doctors struggle to predict which tumors will become aggressive, making it hard to decide on treatment for many men.”
In order to develop a way for doctors to better identify the most aggressive tumors the researchers examined different gene expression patterns in nearly 2,000 prostate tumor samples. Applying a mathematical model called Latent Process Decomposition, the study homed in on a particular pattern of gene expression associated with the most aggressive clinical cases.
The pattern relates to a subtype of cells the team has labeled DESNT, and suggest the more tumor cells in a sample that are of that DESNT subtype, the faster a patient will progress through the disease. The hope is that this can act as a biomarker to stratify prostate cancer patients, identifying those needing more urgent invasive treatments.
"If you have a tumor that is majority DESNT you are more likely to get metastatic disease, in other words it is more likely to spread to other parts of your body,” says Daniel Brewer, co-lead researcher on the project. “This is a much better indication of aggressive disease.”
Identifying when prostate cancer has metastasized is obviously of vital importance in guiding treatment. A team of Australian researchers just published the results of a clinical trial evaluating the efficacy of a new imaging technique developed to provide detailed data on the spread of the disease.
"Around one in three prostate cancer patients will experience a disease relapse after surgery or radiotherapy,” says Declan Murphy, senior author on the new imaging study. “This is partly because current medical imaging techniques often fail to detect when the cancer has spread, which means some men are not given the additional treatments they need.”
Traditional prostate cancer imaging involves a combination of bone and CT scans. The new technique utilizes two different types of imaging, CT and PET. Patients are administered a molecule called Prostate Specific Membrane Antigen (PSMA), which lights up any circulating prostate cancer cells under a PET scan, whereas the CT scan delivers detailed body structure data. So the two imaging techniques combined offer a detailed picture of where in the body prostate cancer cells may be.
The clinical trial results revealed the new technique to be a significant improvement on traditional imaging methods. The PSMA-PET/CT scan effectively detected metastatic cancer spread in 92 percent of patients, compared to the traditional method detecting spread in only 65 percent of patients.
Even more impressively, the new scan delivered low levels of false negatives compared to the traditional method. In 29 patients metastatic cancer was missed by the traditional imaging method, but the PSMA-PET/CT scan only missed metastasis in six patients.
"Taken together, our findings indicate that PSMA-PET/CT scans offer greater accuracy than conventional imaging and can better inform treatment decisions,” says Michael Hofman, study lead from the Peter MacCallum Cancer Centre in Australia. “We recommend that clinical guidelines should be updated to include PSMA PET/CT as part of the diagnostic pathway for men with high risk prostate cancer."
While this new imaging technique can theoretically be implemented around the world relatively quickly, the method is more expensive than traditional diagnostic processes. The researchers are aware of the potential challenges in broadly delivering this new test and are planning an economic analysis to understand how cost-effective this new technique could be. Obviously catching cancer spread early lowers longer term health care costs.
“Costs associated with PSMA-PET/CT vary in different regions of the world but this approach may offer savings over conventional imaging techniques,” says co-author on the new imaging study, Roslyn Francis. “A full health-economic analysis will help to determine the cost effectiveness of introducing PSMA-PET/CT, both from a patient and a healthcare perspective”.
The new genetic expression study was published in the British Journal of Cancer.
The new imaging study was published in the journal The Lancet.