Queensland Premier Anna Bligh has confirmed there have been 11 cancer cases at a school north of Brisbane.

The Government says it will evacuate Deception Bay State High School if investigations confirm there is a cancer cluster on the site.

It is understood that three people have been diagnosed this year, but Ms Bligh says there have been other cases.

"There's about 11 cases of cancer, but two of those were diagnosed before the staff came to the school," she said.

Earlier Education Minister Rod Welford said a number of staff at Deception Bay State High School had developed various types of cancer in the past few years.

"Staff at the school have raised with us a number of incidents of cancer amongst female teachers at the school," Mr Welford said.

"The cancers involve various types of cancers, including breast cancer and thyroid cancer and we've asked my Department to team up with Queensland Health to undertake some preliminary investigations."

Mr Welford says the investigation is urgent.

"We will keep staff informed at every step of the way should it emerge that there is any connection between these cancer incidents and contamination of some kind at the school, then immediate steps will be taken to protect all staff and students," he said.

Teachers and staff are being offered support.

Queensland Health Minister Stephen Robertson says he wants the matter investigated quickly.

"The issue is I think is that you don't ignore statistical anomalies," he said.

"You investigate them thoroughly to determine whether there is a trend or whether you can dismiss it we want to be able to put peoples minds at ease as early as possible.

"We have been keeping a watching brief on it but now that it has got to a particular level, we have offered our service to work with Education Queensland to look at undertaking whatever study is necessary to determine whether there is a broader issue or whether there is not."

Queensland Teachers Union spokesman Steve Ryan says the investigation must be carried out as soon as possible.

He says similar concerns have been raised elsewhere in the past.

"The few that have occurred have not indicated a particular fault of the location but that's not to say it can't occur," he said.

"We need to treat them very seriously - Milpera [State School in Brisbane] had an issue I think last year or the year before.

"Full reports were done and no contamination or problems with the site were actually found in that particular case."