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13th February 2023
A team of UK researchers have developed a novel prostate cancer (PaC) screening test based on measurement of five chromosome conformations that were originally detected in association with advanced PaC and which, together with the prostate specific antigen (PSA) test, has a high degree of accuracy for detecting the cancer.
Prostate cancer is the second most common cancer in men and in 2020, there were just over 1.4 million new cases worldwide. Further investigations for suspected PaC are based on the results of a PSA test and the threshold has conventionally been set at 3 to 4 to differentiate between ‘normal’ and ‘abnormal’ although cancer can be present at lower PSA levels. However, while other tests have been developed, these all generally have a low positive predictive value. While imaging modalities have shown promise as screening tests, the recent PROSTAGRAM study which compared PSA test, MRI and ultrasound, found that all provided a similar level of accuracy for detecting PaC.
In the current study, researchers developed an assay based on specific chromosome conformation changes in certain genes in the blood of men with PaC. Using samples from the PROSTAGRAM study, which included men diagnosed with PaC and control patients, the team set out to establish whether their novel assay (EpiSwitch) in combination with a PSA test could improve the accuracy of PaC diagnosis.
Novel prostate cancer test performance
Samples from 109 men (88 control and 21 with PaC) were analysed. Based on a PSA cut-off level of 3 ng/mL, the test had an accuracy of 79%. The EpiSwitch test alone had an accuracy of only 64% but when the EpiSwitch test was combined with the PSA test, the accuracy was 94%.
The researchers reported that using the EpiSwitch test and the PSA level taken as a continuous variable, there was a high positive predictive (92%) and negative predictive value (94%) for the diagnosis of PaC. Although the study was based on a relatively small number of patient samples, the authors called for further studies to examine the value of the test in larger patient samples.
Pchejetski D et al. Circulating Chromosome Conformation Signatures Significantly Enhance PSA Positive Predicting Value and Overall Accuracy for Prostate Cancer Detection. Cancers 2023
21st November 2022
A prostate cancer screening strategy that involves an MRI scan following a prostate specific antigen (PSA) test with subsequent targeted biopsies, is a more cost-effective strategy than using just a PSA and standard biopsy according to a cost-effectiveness analysis by Swedish researchers.
Prostate cancer (PCa) screening based on PSA, has been shown in a 16-year follow-up study, to reduce prostate cancer mortality. A biopsy is normally used to confirm the diagnosis of PCa though in recent years there has been an increase in the role of magnetic resonance imaging (MRI) as an alternative means for the identification of PCa. In fact, data suggests that the use of multi-parametric magnetic resonance imaging (MP-MRI) might allow 27% of patients to avoid a primary biopsy. In a 2021 study which compared MRI-targeted or standard biopsy for the purposes of screening for PCa, it was found that in men with a PSA level > 3 ng/ml, an MRI result suggestive of prostate cancer was non-inferior to standard biopsy for detecting clinically significant prostate cancer. In the trial, men were randomised to either a 10 to 12-core standard biopsy or to undergo a triage MRI and then a standard biopsy if the MRI results suggested prostate cancer. Given the non-inferior findings of this study, the Swedish team set out to determine the cost-effectiveness of the MRI-based screening approach in men aged 55 to 69 years of age.
The researchers modelled three scenarios: no screening (strategy 1); PSA and standard biopsy every four years (strategy 2) and finally, MRI following an elevated PSA and then a standard biopsy if the men had a PI-RADS value of between 3 and 5, i.e., which is suggestive of PCa. For each of the three strategies, the team modelled several different outcomes including the mean lifetime number of screening tests, MRIs, over-diagnosis (where screening was positive but would not have presented with symptoms before death due to other causes) and deaths. The incremental cost-effectiveness ratio (ICER), which represents the additional cost of one unit of outcome gained by one strategy compared with another, was calculated for each scenario. The ICER was calculated by dividing the difference in costs by the difference in quality-adjusted life-years (QALYs) for the no screening and the two alternative strategies.
Prostate cancer screening and cost-effectiveness
A total of 603 men were randomised to the standard arm and 929 to the MRI arm and of whom, 11.9% underwent MRI or any biopsy.
When compared against a strategy of no screening, the ICER for the MRI and combined biopsies was $53,736 per QALY gained compared to $69,254 for the PSA and standard biopsy strategy and which the authors designated as a moderate cost per QALY gain. Furthermore, MRI-based screening reduced the number of lifetime biopsies and over-diagnosis by approximately 50% and had a high probability of being cost-effective compared to the alternative strategies.
The authors concluded that a strategy for prostate cancer screening based on PSA followed by MRI with subsequent combined targeted and standard biopsies, had a high probability to be more cost-effective compared with the traditional screening pathway using PSA and a standard biopsy.
Hao S et al. Cost-effectiveness of Prostate Cancer Screening Using Magnetic Resonance Imaging or Standard Biopsy Based on the STHLM3-MRI Study. JAMA Oncol 2022