On the advanced prostate cancer online support group there have been some questions raised about how we know when drugs like Zytiga and Xtandi have stopped working. Knowing this as soon as possible is important so that you can quickly move on to the next treatment without giving the prostate cancer time to progress and strengthen itself. On the other hand, we don’t want to abandon a treatment prematurely and not receive all possible benefits it could provide.
In a simplistic and not real world we would assume that changes in your PSA score would be directly linked to changes in disease progression as shown on scans. In other words, as the PSA goes down so does the disease progression and similarly, as the PSA rises disease progression also advances.
A number of people have reported that while their PSA has declined and still continues to decline their scans have not been positive, actually their scans have shown continued and significant disease progression!
The million dollar question is has their treatment failed and should they move on to the next treatment or wait it out and see? This is a great and perplexing question without a simple answer.
I spoke with doctor Daniel Petrylak from Yale University and posed this issue to him. His response was very interesting and very informative. Simply he told me that this is a sign of drug failure. However, he went on to say that there are some fine points to his conclusion. He said that if the man has only one or two new lesions (bone) on the first followup scan and the man’s condition was otherwise stable he would probably recommend a followup scan in a one or two months to determine if this was just a result of a flare. If the new lesions were in soft tissue instead of bone he would not bother with a followup scan and immediately move the man on to another treatment.
To be clear, Dr. Petrylak’s suggestion for another scan is only for the first followup scan. Any additional changes in later scans are clearly a sign of drug failure no matter whether the lesions were in bone or soft tissue.
I would like to thank Dr. Petrylak for his assistance. In the interest of full disclosure he is my primary oncologist and I would recommend him to any man with advanced prostate cancer. He is at Yale University Hospital in New Haven Ct., but he also sees patients at Greenwich Hospital in Ct.
Joel T Nowak, M.A., M.S.W.