Hey @MikeGrant,
First, I'm very sorry to see how many of your family have had aggressive prostate cancer- I can imagine how you feel (I lived through the HIV crisis in San Francisco in the Late 80s and Early 90s - so, I know what it's like to see co-workers, friends, neighbors and even people I didn't like die from an unstoppable disease) and know the terror you are feeling. Being a Top and using condoms, I escaped the HIV crisis - which brings it's own survivors guilt.
But, back to your prostate.
Remember, I'm not a doctor.
Even 4.2 isn't really that concerning considering since you were bike riding a lot before the test. Then, the numbers came down (before the chem castration).
OK, back to today and my advice.
Tell your doctor everything. Seriously, there are two people on this earth you should never lie to and one of them is your doctor. Even if you think it's embarrassing or they will be upset, doctors have literally seen it all. The same doctor you might be worried about telling you're taking chem cast medications has pulled a Barbie Doll out of some dude's ass who claims he sat on it my accident.
So, make an appointment to see your doctor. Take a regular size sheet of paper and write your questions and concerns on it (I use a sharpie so there's no way to miss what the paper is). Keep it to around five questions - you'll be back and can address other concerns then.
1. Father, Brother and Cousin all died from aggressive prostate cancer.
2. Last DRE was "concerning" - Do a DRE this visit.
3. PSA results
4. Taking Adrocur and PSA dropped.
5. Prostate Biopsy?
6. Blood test for genes that cause prostate cancer *
Your doctor isn't the school principle. They aren't going to give you detention for not following the rules. What they are going to give you is 15 minutes of their time and will be grateful that you've laid your reason for the visit out so neatly for them.
I wouldn't wish a prostate biopsy on anyone. But, there are ways to make it tolerable. Most urologists have started to either use lidocaine (like the dentist) to numb the nerves up prior to the biopsy and do it as an in office procedure or they do it in a surgical center and put you under general to do it (like a colonoscopy which 90% of doctors are now doing with general).
So, even though a prostate biopsy ain't like eating chocolate cake, they no longer just tell you to put just up with the pain - the newer methods leave you feeling either nothing or almost nothing. It also has a much higher percentage of men returning for a followup biopsy if active surveillance (formerly called watchful waiting) is the plan. Before the greater use of pain control many men swore they'd never have another prostate biopsy.
You have a right to know exactly where you stand with regards to prostate cancer. Early action could save your life - but, without information, the only thing you have is worry.
It's not easy going through cancer surgery (I've done it - thyroid not prostate), but, it beats having cancer.
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*
https://www.genehealthuk.com/services/prostategene is the website for genetic test that looks for gene mutations for prostate cancer. (My virus checker said it's safe - I did not copy the text as the site has all kinds of copyright warnings on it and the information might change).