Scientists have found the first clear evidence that smoking increases the risk of prostate cancer.

While smoking is already known to increase the risk of a number of different types of cancer, until now, studies linking the habit with prostate cancer have proven contradictory, so scientists in Austria and Switzerland decided to investigate further.

They looked at almost 7,200 men who had been studied in six international cancer research centres. All of the participants had undergone a radical prostatectomy (removal of the prostate gland) as a result of prostate cancer between 2000 and 2011.

The study found that after the prostate gland was removed as part of the treatment for cancer, smokers and ex-smokers were twice as likely to suffer a recurrence of the disease compared to non-smokers.

However, the study also found that this increased risk was offset within 10 years of quitting smoking.

"Our study findings underline the importance of informing a prostate cancer patient about the negative effects of smoking. But it is never too late to quit smoking. On the contrary, as our study shows, it makes sense to quit, even if you are already suffering from prostate cancer," the scientists said.

However, they noted that ‘many questions about prostate cancer and smoking are still unanswered', and they called for further research in this area.

Details of these findings are published in the journal, European Urology.