Reason for ADT

[Victor615]

Why is ADT used after SBRT? If radiation kills the cancer or makes it impossible to reproduce, then why do some doctors recommend ADT?

[Tall_Allen]

If you have unfavorable risk cancer, ADT helps radiation do a better job of killing cancer cells.

[Victor615 in reply to Tall_Allen]

Thank you very much! You are a tremendous resource to prostate cancer patients and your efforts are greatly appreciated.

[janebob99]

Prostate cancer cells "feed" off of testosterone, in particular Dihydrotestosterone (DHT). At low levels of testosterone, i.e., below about 250, there is a linear response of prostate cancer growth versus testosterone level, meaning that more testosterone produces more prostate cancer in the linear regime. SO, lowing testosterone in this linear regime reduces the growth of PCa cells. That's the purpose of ADT (e.g., Lupron or Orogovyx).

Dutasteride is a treatment that reduces DHT levels by 90%, which reduces PCa by 20% (as well as shrinking the prostate by 20-25%). It also treats hair loss ! Side effects include loss of libido and gynecomastia (breast growth).

It get's complicated for testosterone levels above about 250, due to T-saturation effects. This saturation regime affects men who take testosterone replacement therapy (TRT). You're probably not on TRT, though.

Reducing testosterone by castration to reduce PCa growth was discovered by Huggins, et al. in 1941 (he eventually won the Nobel Prize for his work on PCa). He also discovered that administering high levels of estrogen would also effectively castrate men. There is a phase-III study that will be published this Spring (PATCH trial in the UK) that is studying whether or not estrogen patches can replace Lupron shots (with much fewer side effects). If that' sounds interesting to you, I can send you some papers about it.

Bob

[Mascouche in reply to janebob99]

I was not familiar with Dutasteride before reading your reply. From what I read in the search I just did, it appears to act similarly to Saw Palmetto with both showing efficiency but Dutasteride showing a greater one over Saw Palmetto. I'll stick to Saw Palmetto for now but I'll keep the knowledge that there is always Dutasteride if I ever need something stronger.

[janebob99 in reply to Mascouche]

A 20% reduction in prostate cancer growth is a large effect (with Dutasteride). I don't know what the related amount is for Saw Palmetto.

[Mascouche in reply to janebob99]

It is likely not as great for Saw Palmetto though I do not find numbers. From the little I find, the impact is on DHT which the prostate cancer possibly feeds on.

Saw palmetto might help block 5 alpha-reductase, the enzyme that converts testosterone to DHT. Saw palmetto inhibits this conversion, leading to less DHT in the body which in turn lowers its availability

My interpretation is that Saw Palmetto helps reduce DHT, but not as well as Finasteride which it itself not as efficient as Dutasteride.

[janebob99 in reply to Mascouche]

Interesting. I worry about taking supplements where there is little or no data to support their effectiveness. Does your data say how much the DHT is reduced for Saw Palmetto?

Prostate cancer reacts only to DHT, not to testosterone, from what I've read. It "feeds" on DHT, not testosterone. ADT works because reducing testosterone naturally reduces DHT.

I suppose taking saw palmetto can't hurt, but Dutasteride appears to be a more potent medication.

Bob

[Mascouche in reply to janebob99]

I agree with you that Dutasteride appears to be more potent than Saw Palmetto. I haven't found hard numbers on the DHT reduction so far. But funnily enough I have found a few articles that make a comparison on DHT reductions with those drugs and/or supplement but those articles are not about the same serious topic we are all concerned about here, which is prostate cancer. No, those are of a more "frivolous" reason, preventing hair loss. But DHT reduction is DHT reduction, I guess vegamour.com/blogs/blog/saw...

[janebob99 in reply to Mascouche]

Good article about hair loss.

I believe the reduction in DHT levels by Dutasteride is about 90%. You may want to google DHT and prostate cancer...

Bob

[fast_eddie in reply to Mascouche]

I couldn't tolerate finesteride. It caused extreme dental problems -- hyper sensitivity to the point that I agreed to a root canal before I had figured out that finesteride was causing the problems. Two weeks after stopping the finesteride my dental problems went away. I am now experimenting with saw palmetto to see the effect on my next PSA reading. I am only taking half the daily 320 mg dose that seems standard with the supplement. Oh, and I am afraid to take dutasteride given its similarity to finesteride.

[Mascouche in reply to fast_eddie]

It is said that saw palmetto, just like turmeric/curcuma, can lead to false PSA readings. To see what type of impact or not this is truly having on you, you have to remember to stop taking saw palmetto 3 days before your next PSA test.

[Lost_Sheep]

I observe that most of the foci of the replies to your post refer to ADT's ability to weaken the cancer to make it more susceptible to radiation. But your question specified "after".

This pamphlet reports a substantial recurrence of prostate cancer AFTER radiation. So, continuing ADT after radiation may have some benefit. Perhaps "mopping up" stragglers that have been weakened by the radiation to such an extent that ADT might be curative? (My speculation - no medical professional has suggested this to me.)

prostatehealth.org.au/wp-co...

[janebob99]

Thank you for sharing this document. It's really excellent. It confirms that the rate of recurrence after definitive therapy ranges from 10-30%, depending on the risk group and type of treatment. This is the first I've seen hard data to support this.

The mechanism that ADT uses to kill prostate cancer cells is different than surgery (removal) or EBRT (DNA damage). ADT reduces testosterone to castration levels. Since PCa cells are activated by testosterone (they "feed" off of testosterone), lowering the T levels to near zero causes the PCa cells to "starve" to death. That's the primary reason that ADT is continued after doing surgery or EBRT. It's to kill the stragglers...as you said. The time that ADT is prescribed ranges from 4 to 24 months, or more, depending on the risk level and doctor preference.

Estrogen patch therapy is a promising new alternative to Lupron-based ADT, with much fewer side effects. If you're interested in this alternative, private message (chat) your email address to me and I'll send you 10 papers about it.

Bob

[j-o-h-n]

Known as kickback........

Good Luck, Good Health and Good Humor.

j-o-h-n