Compounds found in coffee may combat drug-resistant prostate cancer, research suggests.
Scientists in Japan tested six chemicals naturally present in coffee on prostate cancer cells in mice with the disease.
Two compounds, kahweol acetate and cafestol, were found to suppress the growth of tumours that are normally resistant to widely used chemotherapy drugs.
Similar results were seen in the cell studies.
When the compounds were combined, they appeared to work together to increase their anti-cancer effect.
Lead scientist Dr Hioaki Iwamoto, from Kanazawa University Graduate School of Medical Science, said: “We found that kahweol acetate and cafestol inhibited the growth of the cancer cells in mice, but the combination seemed to work synergistically, leading to a significantly slower tumour growth than in untreated mice.
“After 11 days, the untreated tumours had grown by around three-and-a-half times the original volume (342%), whereas the tumours in the mice treated with both compounds had grown by around just over one-and-a-half (167%) times the original size.”
The compounds are both hydrocarbons found in Arabica coffee beans.
They seem to be affected by the coffee-making process, said the researchers.
While the chemicals remain in espresso coffee, made by forcing hot water under pressure through finely ground coffee beans, they are stripped out of filtered coffee.
Dr Iwamoto warned that it was too soon to think of treating patients with the compounds.
He said: “It is important to keep these findings in perspective.
“This is a pilot study, so this work shows that the use of these compounds is scientifically feasible, but needs further investigation; it does not mean that the findings can yet be applied to humans.
“We also found the growth reduction in transplanted tumour cells, rather than in native tumour cells.
“What it does show is that these compounds appear to have an effect on drug-resistant prostate cancer cells in the right circumstances, and that they too need further investigation.
“We are currently considering how we might test these findings in a larger sample, and then in humans.”
Each year more than 47,000 men are diagnosed with prostate cancer in the UK and around 11,600 die from the disease.
Dr Matthew Hobbs, deputy director of research at Prostate Cancer UK, said: “What’s interesting about this study is that researchers have identified two new compounds which are seemingly able to slow the growth of tumours in mice and in the lab. However, many compounds have shown similar promise at this stage and much more research needs to be done before we can say if this is a real effect that should be tested in men with prostate cancer.
“We fully agree with the researchers that this study does not show that drinking coffee will protect you from prostate cancer.
“Prostate cancer kills one man every 45 minutes in the UK and early-stage exploratory research like this is important if we are to find new ways to treat the disease and save more lives.”
The findings were presented at the European Association of Urology congress taking place in Barcelona, Spain. They were also published in the journal The Prostate.