Singapore, 6 May 2019 - A novel study by the National Cancer Centre Singapore (NCCS) and Canada’s Princess Margaret Cancer Centre, has found that a commercially available genomic test can help to predict outcomes in men with localised prostate cancer.
This genomic classifier (commercial trade name “Decipher”) can identify patients who may be treated successfully with radiotherapy alone. This could potentially spare patients from a course of hormonal therapy, which can cause side effects such as ischemic heart disease, stroke, metabolic syndrome and dementia.
Additionally, they found that the test was more accurate in identifying patients with lethal prostate cancer, who may benefit from combination systemic therapy and radiotherapy.
With this finding, NCCS plans to validate the test in local patients, and ultimately use it to improve patient risk stratification and design bespoke precision strategies in the treatment of localised prostate cancer in Singapore.
Presently, patients are identified for the combined therapy through a classification system endorsed by the US National Comprehensive Cancer Network (NCCN) guidelines. The system classifies intermediate-risk prostate cancer patients into ‘favourable’ and ‘unfavourable’ subgroups based on five clinical parameters – Prostate-Specific Antigen (PSA), positive biopsy cores, Gleason’s score of the cancer, tumour extent, and number of risk factors.
Those in the ‘unfavourable' subgroup are more susceptible to metastatic relapse (cancer recurrence in the distant organs such as liver, lungs, or bones) and death due to prostate cancer. Hence, it is recommended that hormonal therapy is combined with radiotherapy to reduce risk of distant metastasis in these patients.
However, the NCCN criteria remains imprecise, and approximately 30-40 per cent of patients with defined as unfavourable intermediate-risk prostate cancer may still be over-treated with combination hormonal-radiotherapy. This would then expose them to side effects they may otherwise avoid.
To improve the current prognostication methods for prostate cancer, the research team worked with Decipher Biosciences using their clinically validated transcriptome-wide expression profiling assay, the Decipher genomic classifier. This assay classifies men into low-, intermediate- and high-risk for metastasis based on a risk score generated from 22 genes. The Decipher test has been shown in multiple prostate cancer cohorts to predict for lethal relapse following surgery, and these men may benefit from early radiotherapy for salvage treatment. However, it has not been previously studied using diagnostic biopsies from men treated with radiotherapy alone.
In this study, the team performed Decipher testing on biopsies of 121 patients with intermediate-risk prostate cancer treated with high-dose radiation therapy alone. After seven years of follow-up, the overall relapse rate in this group was low, at 15 per cent (24 PSA relapse events). The study cohort comprised of 33 patients classified as ‘favourable’ and 87 patients classified as ‘unfavourable’ by the NCCN classification system.
Decipher reclassified a high proportion of these men (N = 60 of 87) from ‘unfavourable’ to ‘low-risk’ by the Decipher score. When correlated to the relapse rates of these men, Decipher was substantially more accurate than the clinical staging system; with an accuracy of 86 per cent compared to 54 per cent, respectively. Impressively, when the NCCN clinical staging system and Decipher were combined, the accuracy of identifying men with truly high-risk prostate cancer was 89 per cent. These findings, therefore, support the use of hormonal therapy with radiotherapy in these intermediate-risk prostate cancer patients who are Decipher ‘high-risk’.
“This study highlights the added benefit of molecular diagnostics in the era of precision cancer care. Particularly in prostate cancer patients, the study argues for the push to bring well-validated tests into the clinic, so as to improve our current method of risk assessment of these men,” explains Dr Melvin Chua, a senior consultant radiation oncologist at the NCCS. He is also one of the Principal Investigators and a co-Senior author of this multi-centre collaboration.
Decipher testing is commercially available in the United States. Under a research collaboration agreement with Decipher Biosciences, Dr Chua will use the Decipher genomic profiling technology in his laboratory. For the clinical implementation, NCCS plans to validate the test in a local cohort of patients in 2019 to 2020, before rolling it out as a clinical test the following year.
“This is an important research collaboration that aims to better characterise prostate cancer in Asian men, a population whose genomics remains poorly understood,” said Elai Davicioni, PhD, founder and chief scientific officer of Decipher Biosciences. “We look forward to the research with NCCS to determine whether adding Decipher genomic risk in a precision oncology approach to prostate cancer care may improve patient outcomes for men treated in Asia as we have seen for men of African and European-descent.”
The findings of this study were published in the Red Journal (International Journal of Radiation Oncology Biology and Physics – the Official journal of the American Society of Radiation Oncology; impact factor: 5.554), in August 2018.
According to the Singapore Cancer Registry, prostate cancer ranks as the third most common cancer in men and accounts for about one in seven cancer diagnoses. Radiotherapy is a primary modality in the treatment of prostate cancer, with broad utility across different stages and risk groups. In high-risk patients, radiotherapy is combined with hormonal therapy to enhance the effectiveness of radiotherapy on the irradiated tumour and target distant metastases.
About National Cancer Centre Singapore
National Cancer Centre Singapore (NCCS) provides a holistic and multi-disciplinary approach to cancer treatment and patient care. We see close to 65 per cent of the public sector oncology cases, and they are benefiting from the sub-specialisation of our clinical oncologists. NCCS is also accredited by the US-based Joint Commission International for its quality patient care and safety. To deliver among the best in cancer treatment and care, our clinicians work closely with our scientists who conduct robust cutting-edge clinical and translational research programmes which are internationally recognised. NCCS will also launch its Proton Beam Therapy programme at its new centre. NCCS strives to be a global leading cancer centre, and shares its expertise and knowledge by offering training to local and overseas medical professionals. www.nccs.com.sg
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