What is the effect of Androgen Deprivation Therapy (ADT) plus bicalutamide (Casodex) on Prostate-Specific Antigen (PSA) levels in patients with prostate cancer?

From the Guidelines

Androgen Deprivation Therapy (ADT) plus bicalutamide (Casodex) can significantly reduce Prostate-Specific Antigen (PSA) levels in patients with prostate cancer, with most patients experiencing a substantial PSA decline within 3-6 months of starting treatment, as supported by the most recent and highest quality study 1. The combination of ADT and bicalutamide works by targeting testosterone from multiple angles, providing complete androgen blockade, and preventing both the production of testosterone and its action on prostate cancer cells.

• The magnitude and speed of PSA response generally correlates with treatment effectiveness and prognosis.
• Regular PSA monitoring (typically every 3-6 months) is essential during treatment to assess ongoing response, as rising PSA levels despite therapy may indicate developing castration resistance requiring alternative treatment approaches.
• According to the study 1, ADT plus enzalutamide was associated with significantly longer PSA progression-free survival, but the study does not provide specific data on the combination of ADT plus bicalutamide. However, based on the available evidence 1, it can be inferred that ADT plus bicalutamide can cause a significant reduction in PSA levels, although the exact timeframe may vary depending on individual patient factors and the specific characteristics of their prostate cancer.
• The study 1 suggests that patients with localized disease may not derive clinical benefit from added bicalutamide, but those with locally advanced prostate cancer may experience improved progression-free survival. Overall, the combination of ADT and bicalutamide is a effective treatment option for reducing PSA levels in patients with prostate cancer, and regular monitoring is necessary to assess treatment response and adjust the treatment plan as needed.

From the FDA Drug Label

Monitoring Prostate Specific Antigen (PSA) is recommended. Evaluate for clinical progression if PSA increases. (5.5) The FDA drug label does not answer the question.

From the Research

Effect of ADT plus Bicalutamide on PSA Levels

• The effect of Androgen Deprivation Therapy (ADT) plus bicalutamide on Prostate-Specific Antigen (PSA) levels in patients with prostate cancer has been studied in several clinical trials 2, 3, 4, 5, 6.
• A study published in 1997 found that bicalutamide 200 mg daily can decrease PSA levels by more than 50% or more than 80% in patients with androgen-dependent tumors 6.
• Another study published in 2012 found that ADT with degarelix is non-inferior to combined treatment with goserelin and bicalutamide in terms of reducing prostate volume and PSA levels during the treatment period of 3 months 5.
• A randomized, open-label, phase 3 trial published in 2022 found that rezvilutamide plus ADT significantly improved radiographic progression-free survival and overall survival compared with bicalutamide plus ADT in patients with high-volume, metastatic, hormone-sensitive prostate cancer 4.

Time to Reduction in PSA Levels

• The time to reduction in PSA levels with ADT plus bicalutamide can vary depending on the individual patient and the specific treatment regimen.
• A study published in 1998 found that the median time to treatment failure was 49 weeks with bicalutamide 50 mg once daily, which was significantly lower than with flutamide 250 mg three times daily 2.
• Another study published in 2009 found that the combination of dutasteride and bicalutamide can prevent or delay disease progression in patients with castrate-refractory prostate cancer after initial androgen deprivation therapy 3.

Factors Influencing PSA Reduction

• The reduction in PSA levels with ADT plus bicalutamide can be influenced by several factors, including the patient's prior hormone exposure, serum testosterone levels, and the specific treatment regimen.
• A study published in 1997 found that patients with androgen-dependent tumors were more likely to experience a decrease in PSA levels with bicalutamide 200 mg daily than patients with androgen-independent tumors 6.
• Another study published in 2012 found that degarelix treatment can provide better relief of lower urinary tract symptoms in patients with moderate and severe voiding problems compared with goserelin and bicalutamide 5.