For men on ADT who take a drug holiday, what should be the signal to start back on ADT?

It is not uncommon for patients on ADT to seek a “drug holiday;” i.e., a period of time during which ADT is temporarily stopped. But, if a prostate cancer patient has metastatic disease and takes an ADT-free holiday, when should he start again on ADT? 

This new paper looks at a simple comparison. There are two groups of metastatic prostate cancer patients that differ on how early they re-start ADT after a drug holiday. The study is small, with just 65 patients. It is also based solely on a population of Chinese patients. As such, there should be some caution in generalizing the results to other populations.  

Of the two groups, one was made up of patients who started back on ADT "when PSA levels doubled and ≥ 1. 0 ng/mL. " The other had patients who "resumed ADT at PSA ≥ 4.0 ng/mL." The key finding was that the first group had statistically significantly higher progression-free survival. 

The bottom line is that in the metastatic setting, it is probably best to keep ADT-free drug holidays short and not let the PSA climb too high, if one goes on intermittent ADT.

To read the study abstract, please see:


Cai, J., Feng, G., Yan, Y., Liu, Z., & Jing, S. (2019). New protocol of intermittent androgen deprivation therapy for patients with metastatic prostate cancer: A retrospective study. Clinical Genitourinary Cancer, pii: S1558-7673(19)30243-5. Advance online publication.