The accuracy of a frequently cited statistic on cancer survival will soon be subject to independent mediation, it was reported today.

The claim, that 5,000 lives a year would be saved if cancer survival rates were at the European average, has proved contentious after it was cited by ministers, including in a speech by the Prime Minister earlier this year.

The information was also included in a Government leaflet on the NHS. This morning's Daily Mirror reports that the Advertising Standards Authority is due to rule on a complaint about the leaflet in April from former Downing Street adviser John McTernan.

Doubts have been raised about the accuracy of the claim, most notably by Ben Goldacre, but also covered on Full Fact. Because the claim is based on a study that looked at data from 1985 to 1999, it is argued that it does not provide a sufficient guide to comparative survival rates today.

Since the Government has defended the claim in spite of such concerns it means the ASA decision should offer further independent judgement on whether the claim is a legitimate one to still make.

Though the ASA code does not apply to political communications, it does apply to “marketing communications by central or local Government, as distinct from those concerning party policy.”

On the issue of accuracy the code states that “marketing communications must not materially mislead or be likely to do so.”

On how claims should be substantiated, the code states that the marketer, in the case the Government, “must hold documentary evidence to prove claims that consumers are likely to regard as objective and that are capable of objective substantiation.”

It continues: “The ASA may regard claims as misleading in the absence of adequate substantiation.”

So it seems the issue is whether the journal article referenced in the leaflet still counts as “adequate substantiation.”

Mr McTernan's complaint also referred to the guidelines relating to medical products which states that “objective claims must be backed up by evidence”.

The claim on cancer survival rate is not the only section which Mr McTernan complained about. He told Full Fact that the claim in the leaflet that the NHS reforms will give patients more choice also breaches ASA rules on accuracy on the grounds that patients already have a legal right to choose their provider.