The U.S. Food and Drug Administration (FDA) on Monday expanded the approved use of Johnson & Johnson's cancer pill Zytiga to treat men with late- stage castration-resistant prostate cancer prior to receiving chemotherapy.

Zytiga is able to decrease the production of male sex hormone testosterone. In April 2011, Zytiga was initially approved for use in patients whose prostate cancer progressed after treatment with docetaxel, a chemotherapy drug.

In prostate cancer, testosterone stimulates prostate tumors to grow. Drugs or surgery are used to reduce testosterone production or to block testosterone's effects. Some men have castration- resistant prostate cancer, meaning the prostate cancer cells continue to grow even with low levels of testosterone.

Zytiga's safety and effectiveness for its expanded use were established in a clinical study of 1,088 men with late-stage, castration-resistant prostate cancer who had not previously received chemotherapy. Patients who received Zytiga had a median overall survival of 35.3 months compared with 30.1 months for those receiving the placebo.

The most common side effects reported in those receiving Zytiga include fatigue, joint swelling or discomfort, swelling caused by fluid retention, hot flush, diarrhea, according to the FDA.

Source: Xinhuanet