Doctors prescribe caution with insulin's cancer ties

Insulin and the medicines that increase the hormone may boost cancer risk in people with diabetes, said researchers at a diabetes conference.

A review of studies presented by half a dozen doctors, involving thousands of patients, wasn't able to prove the safety of Sanofi-Aventis SA's long-acting insulin Lantus, the investigators said.

European scientists startled medical professionals in June when they reported that Lantus, the world's biggest-selling insulin, may increase the risk of cancer. More research is needed, according to a panel of doctors convened at the European Association for the Study of Diabetes in Vienna.

"I'm not changing my clinical practice because we're not at that stage yet, but I'm certainly aware of the potentially negative effect," said Ulf Smith, EASD president and professor of internal medicine at Goeteborg University in Sweden.

"People need to know there is an unanswered question" about the Lantus risk, said Edwin Gale, professor of diabetes at the University of Bristol in the U.K.

"Physicians ought to at least think about this as they prescribe it."

An internal analysis of all Sanofi studies on Lantus, involving more than 10,000 patients, found no increased risk, said Riccardo Perfetti, senior medical director for Sanofi's metabolism unit. The company is conducting three additional studies to confirm its findings.

The question raised about Lantus may benefit Novo Nordisk A/S's rival long-acting insulin, Levemir. An analysis of studies from the Bagsvard, Denmark-based company found Levemir patients had fewer tumors than those getting traditional human insulin, said David Russell-Jones, from the University of Surrey.