Enzalutamide for the treatment of metastatic prostate cancer if hormone blockers are no longer effective
Enzalutamide has been approved for the treatment of metastatic prostate cancer if conventional hormone blockers no longer work. Even then, many men have no symptoms or only mild symptoms for some time, meaning that chemotherapy is not yet considered. At this stage, the treatment with hormone blockers is either continued as before or used together with non-steroidal anti-androgens (like flutamide or bicalutamide) or abiraterone.
What was enzalutamide compared with?
In 2015, the Institute for Quality and Efficiency in Health Care (IQWiG, Germany) assessed the advantages and disadvantages of enzalutamide compared with the standard treatments in men with metastatic prostate cancer – if treatment with conventional hormone blockers is no longer effective enough and chemotherapy is not yet considered.
The manufacturer provided a study that compared enzalutamide with a placebo. Over 1,700 men took part in it. All of them continued using hormone blockers. The Institute described the placebo treatment as "active surveillance."
What are the advantages of enzalutamide?
- Life expectancy: The study suggests that enzalutamide can increase life expectancy: A quarter of the men had passed away within about 17 months in the active surveillance group, and within about 22 months in the enzalutamide group.
- Bone damage: The study also suggests that enzalutamide can delay complications affecting the bones.
- Severe pain: There is weak evidence that enzalutamide can delay the onset of severe pain: The time it took before a quarter of the men had such severe pain that they had to take opiates was about 4 months in the active surveillance group, and about 10 months in the enzalutamide group.
- Quality of life: The study provided weak evidence that enzalutamide can help to maintain a good quality of life for a longer time.
- Severe side effects: The study also provided weak evidence that enzalutamide delays severe side effects: A quarter of the men had started having severe side effects within about 4 months in the active surveillance group, and within about 8 months in the enzalutamide group.
- Treatment stopped due to side effects: The study suggests that men who take enzalutamide are less likely to stop their treatment because of side effects: During the study, about 26 out of 100 men in the active surveillance group stopped their treatment, compared to about 17 out of 100 men in the enzalutamide group.
What are the disadvantages of enzalutamide?
- Hot flashes: The study provided weak evidence that hot flashes are more common in men who take enzalutamide: About 8 out of 100 men in the active surveillance group had hot flashes during the study, compared to about 20 out of 100 men who were taking enzalutamide.
Institute for Quality and Efficiency in Health Care (IQWiG, Germany). Enzalutamide (new therapeutic indication) – Benefit assessment according to § 35a Social Code Book V. Dossier assessment A14-48. Cologne: IQWiG. March 30, 2015.
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