A large US study has suggested that gay men are more likely to have had cancer than straight men.

The research, from California, found that gay men were almost twice as likely as straight men to have been diagnosed with this disease. On average, diagnoses happened a decade earlier for gay men.

It also found that lesbians and bisexual women are more likely than straight women to report poorer health after cancer.

Researchers are unsure whether gay men may be more likely to have cancer, or whether they are more likely to survive the disease. It is known that anal cancer is more likely to affect gay men and can be caused by HIV.

The study, of 120,000 people, was carried out by using data from the 2001, 2003 and 2005 California Health Interview surveys.

Out of 51,000 men, about 3,700 said they had been diagnosed with cancer as an adult. Just over eight per cent of gay men said they had a history of the disease, compared to five per cent of straight men. Researchers said the difference was not down to differences in race, age or income.

About 7,300 out of 71,000 women in the study had been diagnosed with cancer, but there was no difference between straight, lesbian or bisexual women. However, they were more likely to rate their health after treatment as ‘poor’ or fair’.

Liz Margolies, executive director of The National LGBT Cancer Network, told Reuters that more information is needed to plan care and prevention strategies.

She pointed to research which suggests gay men, lesbians and bisexuals are more likely to smoke and abuse alcohol than straight people and said that LGB people are less likely to visit doctors for health check-ups, partly because of stigma.

“Health care facilities and social service agencies – any organisation that addresses the needs of cancer survivors — must understand the extra challenges that lesbian and bisexual cancer survivors and gay men have,” she said.

Jason Warriner, clinical director for HIV and sexual health at the Terrence Higgins Trust, told BBC News: “We know that HIV can cause certain types of cancer, and that gay men are at a greater risk of HIV than straight men.

“Another factor potentially having an impact is Human Papilloma Virus, which can lead to anal cancer in gay men.

“The government currently runs a national vaccination programme for young girls, but we think recent figures on oral and anal cancers justify taking another look at whether the programme should be extended to include boys.”