Researchers at the Department of Urology, Centre Hospitalier Universitaire du Québec (CHUQ), Quebec, Canada evaluated the rate and duration of prostate-specific antigen (PSA) response to high-dose bicalutamide (150 mg) in men with non-metastatic castration-resistant prostate cancer (nmHRPC) as well as its impact on the duration of metastasis-free survival. They concluded that high dose bicalutamide is capable of inducing a PSA response and in extending progression free survival even if the man is hormone resistant.

The study was a single site, prospective study that included only 38 men with nmHRPC. All the men were surgically or medically castrated and had PSA increases above their nadir after previous antiandrogen manipulation. Additionally, none of the men showed signs of any bone metastases.

The men were given a daily dose of bicalutamide (Casodex) of 150 mg. Complete clinical evaluations and PSA tests were performed every 3 months on all of the men. The researchers defined the experimental response if the PSA declined from baseline of either >/= 50% or >/= 85%. The duration of response was the time from entering into study until PSA increased >/= 25% or >/= 2 ng/ml from the nadir. Additionally, the researchers performed bone scintigraphy at PSA increase or at symptom appearance.

With the mean follow-up was 34.5 months (range, 3-75.2) they found:

* There was a PSA decline that met the research defined end points in 17 of 38 men (44.7%).
Seven of the men (18.4%) had a PSA decline >/= 85%
Ten of the men (26.3%) had a PSA decline >/= 50%

* The median duration of response was 18.5 months for partial and 37.4 months for
complete responders.

* The median time to metastasis was 52.5 months for responders and 15.7 months for
non-responders (Log-Rank test 9.3, P = .002).

The conclusions were that high-dose bicalutamide could induce a second response in almost half of castration-resistant prostate cancer patients who do not have signs of metastasis. The duration of response is more than 1.5 years on average and responders have prolonged metastasis-free survival.

This study needs to replicated with a much larger subject pool. We also need to evaluate whether high dose bicalutamide can have a similar effect when there are both low levels and high levels of metastatic disease present.

THE TAKE HOME MESSAGE:
Men without signs of metastatic disease and who are also hormone refractory should consider discussing the possibility of using high dose (150 mg) bicalutamide as a treatment to control PSA and extend the time to disease progression.

Reference:
Urology. 2010 Mar 17. Epub ahead of print; Lodde M, Lacombe L, Fradet Y
PubMed Abstract
PMID:20303155

Joel T Nowak, MA, MSW