Well-cooked meat 'may increase risk of bladder cancer'-
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Cooking meat at high temperatures or until it is well done could increase the risk of bladder cancer, experts claim.
The warning to barbecue-lovers adds weight to other research which suggested charred meat may cause other cancers, including pancreatic cancer.
In the latest study, scientists found that people who eat meat regularly, especially meat that is well done or cooked at high temperatures, may have a higher chance of developing bladder cancer.
A 12-year study of 884 people with bladder cancer and 878 without it found people who consumed a lot of red meat were 48 per cent more likely to suffer bladder cancer than those with a low intake.
Over time, experts have shown that cooking meats at high temperatures creates chemicals not present in uncooked meats.
These heterocyclic amines (HCAs) are carcinogenic and are formed from the cooking of meats such as beef, pork and chicken.
HCAs develop when amino acids (the building blocks of proteins) and creatine (a chemical found in muscles) react at high cooking temperatures.
According to the National Cancer Institute in the US, experts identified 17 different HCAs that 'may pose human cancer risk'.
The latest study was led by Jie Lin, an assistant professor at the University of Texas, and was presented at the American Association for Cancer Research annual meeting in Washington DC.
The team looked at the association between meat intake, HCAs and bladder cancer.
The National Cancer Institute's food frequency questionnaire was used to assess dietary intake of different meats.
The results were split into four groups, from the lowest to the highest meat intake.
Compared with those in the lowest group of red meat intake, people were 4 per cent more likely to develop bladder cancer if they were in the third group up and 58 per cent more likely if they were in the second highest group of red meat intake.
Those people in the top group - people who consumed the most red meat - were 48 per cent more likely to suffer bladder cancer than those with the lowest intake.
'Higher intakes of beef steaks, pork chops and bacon were each associated with increased bladder cancer risk in a dose-response pattern,' the researchers said.
In addition, people who ate a lot of fried chicken and fried fish were at 'significantly increased risk'.
Red meats that were either medium or well done were linked with a 46 per cent and 94 per cent increased risk of cancer respectively compared with those that were cooked only long enough to still be rare.
When 177 people with bladder cancer and 306 people without the cancer were analysed separately, experts found that those with the highest estimated intake of three specific HCAs were more than two-and-a-half times as likely to develop bladder cancer as those with low estimated HCA intake.
The researchers also analysed each person's DNA to look for genetic variants in how the body responds to HCAs which interact with red meat intake to increase the risk of cancer.
They found that people with seven or more unfavourable genotypes who had the highest red meat intake were almost five times as likely to suffer bladder cancer as those without.
'These results strongly support that red meat intake and genetic variants in the HCA metabolic pathways jointly influence bladder cancer susceptibility,' the experts concluded.
Professor Xifeng Wu, who worked on the study, said: 'These results strongly support what we suspected: people who eat a lot of red meat, particularly well done red meat, such as fried or barbecued, seem to have a higher likelihood of bladder cancer.
'This effect is compounded if they carry high unfavourable genotypes in the HCA-metabolism pathway.'
Ms Lin said: 'It's well known that meat cooked at high temperatures generates HCAs that can cause cancer.
'We wanted to find out if meat consumption increases the risk of developing bladder cancer and how genetic differences may play a part.'
More than 10,000 new cases of bladder cancer are diagnosed each year in the UK.
Around 5,000 people die from it every year, and almost 90 per cent of deaths are in people over 65.
Dr Panagiota Mitrou, science programme manager for the World Cancer Research Fund, said: 'These are interesting findings that add to the evidence on the links between meat and cancer.
'The results should, though, be treated with caution as they are based on a single study. They would need to be replicated in other studies before we could make any conclusions.
'When we looked at all the evidence on meat and cancer, it did not suggest meat increases risk of bladder cancer.
'There is, though, convincing evidence that red and processed meat increase risk of bowel cancer.
;This is why we recommend that people aim to limit consumption of red meat to 500g - cooked weight - per week and to avoid eating processed meat.'
According to the UK Food Standards Agency (FSA), people can reduce their risk from chemicals that may cause cancer by not allowing flames to touch food when barbecuing or grilling, and cooking at lower temperatures for a longer time.