Recent news reports detail an Australian cohort study that compared the mens' risk of getting prostate cancer with whether they had asthma.  The researchers followed 17,000 men of all ages for an average of 13 years to see if they developed prostate cancer.  They compared this with the men's asthma status.

They found that men who reported using steroids to control asthma had a significantly higher risk of developing prostate cancer than men who did not.

However, this does not mean that using asthma medication increases the risk of prostate cancer in people with asthma.  There may be other factors causing prostate cancer here.

The researchers tried to adjust the statistics to take into account factors such as age, alcohol and smoking.  But they didn't take others into account, such as family history or physical activity.  This sort of study is difficult to interpret because we don't know what else causes prostate cancer, nor how much each factor increases the risk.  This is why we can't conclude that inhalers cause prostate cancer from this study alone.  

We should, however, see more research into this area.

Links to more details

• NHS Choices Behind the Headlines report
• Read the abstract or full text of the research:  [Severi G et al,  Asthma, asthma medications, and prostate cancer risk. 2010]
  
• Other information about risk factors and causes of prostate cancer from UK Prostate Link