Men with prostate cancer who smoke significantly increase their chances of dying of the disease, a study has found.
Researchers also linked smoking at the time of diagnosis with aggressive tumours.
Study leader Dr Stacey Kenfield, from the Harvard School of Public Health in Boston, US, said: "We found similar results for both prostate cancer recurrence and prostate cancer mortality.
"The data taken together provide further support that smoking may increase risk of prostate cancer progression."
The research, published in the Journal of the American Medical Association, is the largest investigation to date looking at the effects of smoking on prostate cancer.
More than 5,300 men diagnosed with prostate cancer between 1986 and 2006 took part in the Health Professionals Follow-Up Study.
Men with prostate cancer who were current smokers had a 61pc increased risk of dying from the disease compared with non-smokers. They had a similarly increased risk of recurring cancer.
Smoking was associated with more aggressive disease at diagnosis.