Cancer screenings have been missed and criminal convictions overlooked because of how data is collected about people’s biological sex and gender identity, an independent review found.

The review, led by Prof Alice Sullivan, outlined the risks of conflating biological sex and gender when it comes to clinical care, sex-specific cancer screening and safeguarding.

Prof Sullivan, a professor of sociology at University College London, urged public bodies to collect data on both sex and gender identity by default “across the board” to ensure it is accurate.

The Department of Health said the findings would be considered with “the gravity they deserve, as it reforms gender identity services across the board”.

Prof Sullivan said “a confusion between sex and transgender and gender diverse identities” had developed in recent years and there had been attempts to “merge these two things into one variable”.

While people can legally change gender, they can’t change biological sex. This means a woman who transitions to become a man may still need cervical smears and transgender women may need prostate checks.

Prof Sullivan told BBC Radio 4’s Today programme there is no reason for a “trade off” between recording data on sex and gender.

“What I’ve argued in this report is that sex is really important, we should be recording it by default – transgender and gender diverse identities can also be recorded where that’s appropriate,” she said.

“There’s no reason to see this as a trade-off between the two. They’re two distinct variables.”

The report, commissioned by the previous Conservative government in February of last year, also raised concerns about policing as suspects do not have to tell officers that they have changed their name or gender.

It is possible someone could be released from custody before their offending history is known about, the review said.

The report recommends that police forces record data on sex in their systems and stop allowing changes to be made to individual sex markers on the police national computer.

It also said new NHS numbers and changed gender markers should no longer be issued.

She urged the government to implement the recommendations “across the board”.

“I’ve recommended that data on sex should be collected by default in all research and data collection commissioned by government and quasi-governmental organisations, and I think implementing that would make a huge difference,” she said.

“I think we need leadership, because people are confused and they’re anxious.”

A government spokesperson said: “This government is clear that the collection of accurate and relevant data is vital in research and the operation of effective public services, particularly when it comes to sex.”

The review has been shared with the Office for National Statistics and other departments, the spokesperson added.

Prime Minister Keir Starmer’s spokesperson said civil servants were taking action to make sure the right guidance is in place.

“There’s obviously circumstances for recognising people’s gender, but the importance of biological sex, when it comes to, for example, healthcare, is common sense,” he added.