I think two months of pre-treatment (called "neo-adjuvant" therapy) is the current standard, but there's nothing magic about
that. Some used to do 6 months of neoadjuvant ADT until a randomized clinical trial at Mayo showed that 2 months worked as well as 6 months:For Neoadjuvant Androgen Suppression in Prostate Cancer, 8 [weeks] is Enough
However, an Australian study showed that 5 months was better than 2 months:Short-term neoadjuvant androgen deprivation and radiotherapy for locally advanced prostate cancer: 10-year data from the TROG 96.01 randomised trial
So which is right? Well, there's a chance they're both wrong! The reason is because the radiation dose was only 66 Gy in the Aussie study and only 70 Gy in the Mayo study. These doses are far below the 80 Gy of IMRT now considered curative. More importantly, both of those studies only looked at short-term ADT - it was stopped at the end of EBRT. A more recent clinical trial (DART 01/05) proved that long-term ADT (28 months total) worked better than short-term ADT (4 months total) even with dose-escalated EBRT of about
80 Gy. Now, in both arms of that study, ADT was begun 2 months before EBRT, so it doesn't really tell us how long the neoadjuvant phase should last.Androgen deprivation therapy (ADT) and escalated dose in radiation therapy (RT)
Others say that what matters is not
the duration of the neoadjuvant ADT, but whether it radiosensitizes the cancer cells properly. And the way to tell that is to check the PSA. If the PSA has become undetectable or close to, the pre-treatment is optimum, and the radiation can begin.PSA response to neoadjuvant androgen deprivation is an independent prognostic marker and may identify patients who benefit from treatment escalation
Now, if you read the subsection in my article titled "ADT sequencing," there is a study that says that whether the ADT is started before or during the EBRT makes no difference. I rush to add that that study looked at patients treated from 1995 to 2002 when doses were substandard.
There has never been a randomized clinical trial in the era of dose escalation, so a definitive answer is elusive for now. In the meanwhile, almost everyone using conventional IMRT follows something close to the protocol used in DART 01/05 because we know that works.
Allen - not an MD
•PSA=7.3, prostate volume=55cc, 8/17 cores G6 5-35% involvement
•SBRT 9 yr onc. results
•SBRT 7 yr QOL results
•treated 10/2010 at age 57 at UCLA,PSA now: 0.2,no lasting urinary, rectal or sexual SEsmy PC blog