BruceSF sent me this message and it looks like a game changer for those trying to prevent recurrence, to me:
I’ve been taking Prazosin for 4 years since my radiation therapy, it is a drug that helps urinary flow (same family - alpha blocker - as Flomax) and lowers blood pressure and still have an undetectable PSA based on this article : nature.com/articles/s41598-...
It seems to be effective at lowering recurrence rates in a retrospective study in Australia.
Not at all. It was only a retrospective study, showing association not causation.
Seems like if I have to be on an alpha blocker, I might as well be on this one, No?
There are a half a dozen - use whichever works for you. I liked Rapaflo (silodosin) best.
Study was highly favorable towards control group
Following stratification into risk groups using the NCCN guidelines described in the methods section, it was observed that a higher proportion of patients in both tamsulosin (62.50%) and prazosin groups (57.10%) were identified as high risk when compared to control (41.70%). Similarly, both treatment groups were shown to have a higher proportion of patients with locally advanced disease (defined by the European Association of Urology (EAU) as tumour staging at diagnosis of T3 or T4)28. In the tamsulosin group 38.90% of patients were diagnosed with T3/T4 disease while 19.10% of prazosin patients received the same diagnosis. In comparison, only 14.30% of control patients had T3 disease with no patients identified as having T4 disease at diagnosis. Further to this, prostate biopsy pathology results revealed that 41.50% of tamsulosin patients and 43.50% of prazosin patients had a Gleason score of 8–10 indicative of high grade, poorly differentiated prostate cancer29. In contrast, only 25% of control patients had a Gleason score of 8–10 at initial diagnosis. The full patient demographics are shown in Table 1.
You don't seem to understand my comment. Retrospective studies are particularly bad at comparing treatments. Maybe these will help:
ascopubs.org/doi/full/10.12...
onlinelibrary.wiley.com/doi...
But I agree - take whichever works best for you.
As a trader who has looked at charts all my adult life, this one is hard to ignore, even if just association.
As someone who understands research methods, perils and pitfall like the back of my hand, it is very easy to ignore. Ask yourself this question: people who take prazosin, usually take it for hypertension - what other drugs are they taking? How often do they get seen by doctors?
So they were not taking it for prostate/ urinary issues?How do we know this?
The prazosin arm all had PCa
Prazosin (minipress) is prescribed for hypertension - has been for many years. The authors found patients who were taking prazosin and who also had prostate cancer. Both prostate cancer (incidence: 1 in 7 men over a lifetime) and hypertension (incidence: 75% of men over 60) are highly prevalent. That's why they were able to find men who had both.
I am starting to see why you don't like these studies, thanks for the explanation.
It may or may not actually help - I have no opinion. But they will have to do a randomized trial before we can accept the hypothesis that it works. Meanwhile - your choice.
I know how you hate relying on retrospective studies. And for good reason. Out of curiosity can you think of a few examples of meaningful randomized trials that confirmed earlier retrospective trials ? I’d think it happens a lot. Retrospective trial shows causation leading to a randomized trial that proves causation?
Schwah
There have been some - whatever has been proven in a Phase 3 RCT probably once showed promise in a retrospective study. That's their whole purpose - to generate hypotheses for more rigorous testing. More often, they fail at Phase 3 and we forget about them.
But, am I correct snd assuming just because they failed at phase 3 doesn’t mean they failed because the causation was the reason for failure. Most likely funding is the reason?
Phase 3 proves causation
Only if there is profit to be made if it is a patented drug or funded by government. But im sure many small drug companies drugs would prove successful if they could secure the very large cost of going through phase3. For example an old repurposed drug that the patent has run out would never make it to phase 3 unless federally funded. Am I thinking wrong on this?
That's what governments exist for! For repurposed drugs, there are other sources of funding - NIH/NCI, PCF, DoD, and in other countries. CHAARTED, for example, proved the benefit of docetaxel, a generic drug out of patent, for mHSPC. Similar Phase 3 trials were conducted by the UK and France. SELECT was also NCI funded. Every year DoD approves trials that do not have private funding.
Thanks TA, i never looked or noticed where on the clinical trials where the funding came from. I also wasn’t aware of docetaxel being out of patent.
TA, do you agree that selection bias is less likely in the retrospective study of prazosin, since it was greatly superior to not only controls but also to the second BP medication, tamsulosin, to which it is relatively but not entirely similar?
To boot, preclinical data shows prazosin, but not tamsulosin, having efficacy on prostate cancer cell lines / models.
No, it seems to me selection bias is much more likely. Prazosin is usually given to men for high blood pressure.
I just got a prescription for omnic ocas which is tamoulisin I think. Can’t see the harm in asking to switch though. Thanks for posting
Thanks . I 'll share that with the MO in the clinic . I am getting IMRT at a GenesisCare clinic in Spain .
Thanks very interesting.
Refresh my memory if it serves me correctly...
Wasn't there an issue with Alpha Blockers masking PSA readings? Thereby making it "seem" it was lowering it, but not really having any effect on PCa. This is and could be problematic, no?
I know in "my" situation/experience, that's exactly what was happening in the interim between diagnosis and my first line treatment (RP). I was prescribed an Alpha Blocker for BPH as my PSA was dropping... So then, in my search for answers I remember coming across some information related to that. Don't have links or anything...
Anyways. Just a question 
Seeing if my brain is still working correctly, lol
Best Regards
Thanks I think that was discussed here
Coolone, maybe you're thinking of 5 alpha reductase inhibitors - it is thought that they may reduce psa and masking advanced disease, which came up because the patients using them had higher gleason scores at diagnosis than those who didn't. I don't think alpha blockers do that.
I took Tamsulosin (Flomax) for a few years after SRT. Eventually it gave me bradycardia and I had to switch to solifenacin. I am now just starting with Myrbetric since solifenacin gave me constipation.
Urology
Volume 145, November 2020, Pages 216-223
Pediatric Urology
Prostate Cancer Risk and Prognostic Influence Among Users of 5-Alpha-Reductase Inhibitors and Alpha-Blockers: A Systematic Review and Meta-Analysis
Author links open overlay panelYougenWu1YangHong14
doi.org/10.1016/j.urology.2...
Get rights and content
We systematically assessed the effect of 5-alpha-reductase inhibitors (5-ARIs) and/or alpha-blockers use on prostate cancer (CaP) incidence and outcomes, including CaP pathologic progression, CaP-specific mortality, and all-cause mortality. 5-ARIs but not alpha-blockers decreased risk of overall CaP, low grade CaP (Gleason < 7), and delayed CaP pathologic progression. Both 5-ARIs and alpha-blockers had no significant impact on risk of high grade CaP (Gleason ≥ 7), CaP–specific mortality, or all-cause mortality. Our result suggested that finasteride should be given for at least 4 years if used for preventing CaP.
I would suggest that the retrospective study,showing benefits for prazosin user patients, has a better chance than the average retrospective study of the drug in question to actually be beneficial.
Users of prazosin have a worse cancer status than controls, otherwise they have no apparent dissimilarities..Selection bias could clearly play a role as is so often the case with retrospective studies. Users of P might have more healthy behavior, better health insurance and so on than the PCa patients not on BP medication. But the users of the second BP medication, tamsulosin, did in most respects not have an improved outcome compared to controls, and had a greatly inferior outcome compared to prazosin. Why is this? Of couse there can be confounders, but at the least, it is not obvious that users of tamsulosin have worse health behavior etc than users of prazosin. P and T are similar drugs, both being α1-adrenoceptor antagonists
Then there are the preclinical studies, maybe of limited use on their own, but buttressing what clinical data there is. From the study referenced by Scout4answers: “There is substantial evidence that the quinazoline α1 antagonists (terazosin, prazosin and doxazosin) display cytotoxicity in prostate cancer cell lines, effects that are not observed with the sulphonamide derivative tamsulosin. ........ In vivo studies in mice have shown that these effects also occur at clinically relevant doses, with reduction in tumour growth, metastasis and decreased angiogenesis observed in models of prostate cancer”
So lab and animal studies show protective effects from prazosin but not from tamsulosin. The retrospective study on men likewise showed a greatly superior effect of P compared to T and controls.
This is of course very far from any proof of efficacy of P for PCa, which will need a RCT phase 3 years ahead in the future if there ever is one. But the combination of lab/animal data and retrospective study pointing in the same direction to me indicates that it could be worthwhile considering prazosin, if side effects are tolerable and in particular if one has an interest in lowering blood pressure. As for my own case, I have 125/70 not high, but far above ideal I would like systolic to be below 110. This post set my mind racing and I invite any comments.
Unfortunately it only works in OZ.....
Good Luck, Good Health and Good Humor.
j-o-h-n Friday 06/10/2022 6:53 PM DST
Yes, that's what I did. I had a little bit of light headedness when I started the prazosin, but that went away. Now I take a tamsulosin in the morning and 2mg of prazosin at night and it seems to be good for blood pressure and urinary flow, and hopefully my next PSA will remain undetectable.
I'm not sure.... but I am sure that Ms. N. wrote "Never give a Moose a Munchkin"....
Good Luck, Good Health and Good Humor.
j-o-h-n Saturday 06/11/2022 1:15 PM DST
"It is hoped that this study will help determine if it is possible to use prazosin while participants are completing radiotherapy, and help guide the development of a large scale clinical trial which will be used to investigate the efficacy of prazosin combined with radiotherapy".It will take some time before results are in. Why wait?
I did brachy boost therapy followed by metastasis directed radiation a year ago. Want to improve odds of cancer continuing staying quiet and I find no obvious reason why prazosin won't work without RT, if it works with RT.
