Accuracy & Equity in Prostate Cancer Diagnosis in New Zealand
A New Approach to Prostate Cancer Diagnosis
Prostate cancer is the most commonly diagnosed cancer in New Zealand, and there are significant disparities in terms of diagnosis, treatment, and outcomes. Our project at Mātai aims to change this.
We’re using advanced MRI techniques to improve how prostate cancer is diagnosed. This approach helps doctors decide whether a biopsy is needed and assists in performing targeted biopsies. Not only does this method help diagnose more serious prostate cancers, it also reduces the diagnosis of less serious cases and reduces the overall need for biopsies.
Our project, generously supported by the Hugh Green Foundation and the Prostate Cancer Foundation of New Zealand, has already introduced this new diagnostic pathway in Tairāwhiti. By showing how effective this pathway is, we hope to advocate for it to become the standard of care throughout Te Whatu Ora Tairāwhiti.
Prostate Cancer: The Current Scenario
At present, the standard practice in New Zealand is to perform a non-guided biopsy based on age and PSA levels. This method has several drawbacks:
– It often misses the tumour (in about 25% of cases)
– It can lead to underestimation of the tumour’s size
– It may unintentionally detect non-significant cancer
This current approach falls short in identifying younger men with significant, but treatable disease. It also has a low rate of screening in the most vulnerable populations and in populations most likely to benefit.
Our Approach: MRI and Targeted Biopsies
Our new diagnostic pathway uses MRI before a biopsy, which helps identify about 30% of men who can avoid invasive biopsies. We’ve worked with GE Healthcare to develop a 10-15 minute MRI scan protocol, much faster than the standard scan time of up to 45 minutes. This reduction in time lowers costs and enables more widespread use.
Furthermore, performing a targeted biopsy allows for better understanding of the size, grade, and location of prostate cancers. This information is essential for personalized treatment planning.
Prostate Cancer in New Zealand
Prostate cancer is a major health concern in New Zealand, with about 30,000 men living with prostate cancer that requires surveillance. Every year, around 650 New Zealand men die from prostate cancer. The 5-year survival rate is 98% with early diagnosis and drops to less than 20% if diagnosed late.
Inequalities in Prostate Cancer Outcomes
Men living in rural locations face higher mortality rates from prostate cancer and have lower screening rates, less intensive diagnostics, longer wait times, and later diagnoses. Our new diagnostic pathway aims to provide an equitable service which will improve prostate outcomes for all men in Tairāwhiti.
If you want to see how well this pathway has reduced unnecessary biopsies, please see the evolving results here:
Current Prostate Diagnostic Pathway Results Summary for Tairāwhiti
241 men with PSA greater than 4 have had a pre-biopsy MRI on the hospital 1.5T scanner.
24.1% of these men had an MRI that suggests biopsy can be avoided and that continued PSA monitoring with possible followup MRI can be performed.
75 men with PSA greater than 3.5 have had a pre-biopsy MRI on the Mātai 3T scanner.
44.0% of these men had an an MRI that suggests biopsy can be avoided and that continued PSA monitoring with possible followup MRI can be performed.
52 men have had a biopsy using the transperineal biopsy system at the hospital which allows targeted biopsies of any suspicious findings seen on the pre-biopsy MRI.
73.1% of men undergoing biopsy received a diagnosis of significant prostate cancer. These men need to have a discussion with their urologist regarding additional tests such as CT or PSMA PET. Most of these cancers will require treatment. Some can be closely watched.
11.5% percent of men undergoing biopsy received a diagnosis of low grade prostate cancer. Only a small number of these cancers require treatment. Most of these low grade cancers can be followed and are not thought to be life threatening.
The decision to treat versus followup as well as the best way to treat is made based on conversations with the urologist.
Of the 45 moderately suspicious findings on MRI that were targeted for biopsy, 48.9% of these turned out to be a significant cancer. 17.8% of these turned out to be a low grade cancer.
Of the 26 highly suspicious findings on MRI that were targeted for biopsy, 84.6% of these turned out to be a significant cancer. 3.8% of these turned out to be a low grade cancer.
Only 3 significant cancers were detected away from suspicious MRI findings. This happened in 7.3% of men undergoing biopsy.
We think these number are pretty good. If the MRI finds something abnormal, there is a good chance it is cancer.
77.8% of the targeted biopsy results were felt to be concordant – meaning that even if the biopsy result is something other than cancer – the MRI appearance is still felt, even in retrospect, to have warranted a biopsy. We would like this number to be close to 100% – but there will always be findings on the MRI that look like cancer but are actually not cancer.
A good target for this number is 75%.
Summary
In summary, pre-biopsy MRI has allowed 28.8% of men being able to potentially defer biopsy. 84.6% of men undergoing biopsy were found to have prostate cancer. This suggests that the risk of a man with PSA over 3.5 having an unnecessary biopsy is low.
11.5% of men had low-grade prostate cancer. There is always the risk of over-treating these low-grade cancers so we would like to reduce the number of low-grade cancers that we detect.
With targeted MRI follow-ups after regular screening, we’re minimising the intervention cascade after PSA tests, and improving prostate cancer outcomes for men.
Evolving Results
If you want to see how well this pathway has reduced unnecessary biopsies, please see the evolving results here
Click HereGet Involved
If you are under 70 years old and have a PSA level higher than 3, you may be eligible to participate in this new approach. If you are concerned about prostate cancer, speak with your GP about prostate cancer screening with a PSA blood test and physical exam.
For students interested in auditing the clinical service, please reach out to us for potential opportunities.
Watch the On Target Docuseries, filmed by international film-maker Mikey Kay
Thank you to our funders:
