Researchers in Ontario took a retrospective look at data collected over 20 years on men who had been prescribed ADT over at least a five year period. The men were all over the age of 65 and residents of Ontario. Of the 8544 men in the study, only one in six received intermittent ADT. The rest received continuous ADT, even though it’s been shown that intermittent ADT doesn’t negatively impact survival (particularly if men are non-metastatic at the outset of ADT). The researchers wanted to know why more men on ADT were not encouraged to go intermittent.
A nice and uncommon feature of this real–world study was that the researchers looked at characteristics of not just the patients, but also the clinicians treating those patients. Four variables stood out as predictors of intermittent ADT use. Patients who were financially well-off and had prior treatment for localized prostate cancer were most likely to go on intermittent ADT. They were also more likely to be on intermittent ADT if they were treated by a radiation oncologist rather than a urologist…and preferably a clinician who had been in practice at least 10 years.
The authors are cautious in their speculations about why these factors stood out. They did not have information on education levels for the patients, but many studies on the health impact of socioeconomic status have shown that those who are financially well-off are usually better educated. In turn, those who are better educated are typically more attentive to their health.
We thus expect those men, who had previously been treated for localized prostate cancer and are well educated, to be watching their PSA intently. With better patient engagement and compliance in monitoring PSA, they may be more likely to be good candidates for intermittent therapy.
To extend the speculation, one might guess that patients who eventually get prescribed ADT and go on intermittent therapy are ones who were getting PSA tests regularly and often before they had any prostate cancer treatment. That’s a testable hypothesis, but it is not discussed in this paper. That is understandable since the databases the researchers accessed did not have patients’ PSA history.
One way to get at this idea, though, would be to look at other populations in other parts of the world where PSA tests are more commonly used to screen for prostate cancer. Our hypothesis is that the proportion of men who go on intermittent ADT will be higher in places where men more commonly get regular PSA tests.
To read the study abstract, see: https://pubmed.ncbi.nlm.nih.gov/34412510/
Timilshina N, Komisarenko M, Martin LJ, Cheung DC, Alibhai S, Richard PO, Finelli A. Factors Associated with Discontinuation of Active Surveillance among Men with Low-Risk Prostate Cancer: A Population-Based Study. J Urol. 2021 Oct;206(4):903-913. doi: 10.1097/JU.0000000000001903. Epub 2021 Aug 20. PMID: 34412510.