Two law firms say they are preparing a claim against Hamilton's Marchese Health Care on behalf of cancer patients in Ontario and New Brunswick who reportedly received chemotherapy cocktails at lower-than-prescribed doses.

Law firms Siskinds LLP and Strosberg, Sutts LLP said they are trying to contact individuals who received the diluted chemotherapy treatments.

According to Cancer Care Ontario, patients in Oshawa, Peterborough, London and Windsor were given doses of cyclophosphamide, used to treat cancers including breast and non-Hodgkin's lymphoma, that had been mixed with too much saline solution.

And a representative from Horizon Health Network in the Saint John area of New Brunswick said as many as 186 of its cancer patients received watered down chemotherapy treatments since March 2012.

The premixed bags of a chemotherapy drug and saline solution were prepared by Marchese Health Care, Cancer Care Ontario said. The supplier produces and labels these medications.

"This is a shocking revelation for cancer patients affected by this error," said Harvey Strosberg, the lead lawyer for the affected patients. "As Canadians, we count on world class health care, and we expect and deserve long-term cancer treatment to be done seamlessly and expertly."

Marchese Health Care's CEO Marita Zaffiro issued a statement on the company's website on Wednesday. The company, she said, is not at fault for the drug dilutions and the errors "were the result of the use of our preparation" and not the product itself.

Zaffiro and her staff "are confident that we fully met all of the contract requirements including both volume and concentrations for these solutions," she said.

"However," Zaffiro noted, "we share responsibility to ensure that patients and their families are not given any reason for concern about their treatment. We take this responsibility very seriously."

More than 1,100 patients affected

More than 1,100 patients in Ontario and New Brunswick were given lower than intended doses of cyclophosphamide and gemcitabine. The chemotherapy is part of a regime for breast and lung cancer as well as lymphoma and leukemia.

The premixed bags contained too much saline solution, which diluted the chemotherapy agent.

"Our understanding is from the hospitals this drug may have been to 20 per cent under the dose expected and hypothetically, one would imagine if only one dose was delivered at three per cent less than intended of a 12-dose regimen it would be very unlikely to have any impact, but it is difficult to speculate beyond that because of the unique circumstances of each patient," Dr. Carol Sawka, vice-president of clinical operations at Cancer Care Ontario, said in an interview today.

A pharmacy technician in Peterborough identified the error when an IV bag seemed too full.

"[In] the bag that they were using, the solution that had been provided by the supplier seemed to be a little bit larger than the other ones and so through some inquiry and due diligence on their part they felt that there was an issue and then they notified us because they knew that we were also using it and from there we all commenced to try and investigate what was actually happening," said Neil Johnson, vice-president of cancer care at London Health Sciences Centre.

The Institute for Safe Medication Practices Canada, an independent not-for-profit agency, said the source of the overdilution problem is the common manufacturing practice of including excess or overfill volume in commercially available IV bags.

"An opportunity exists to create and implement a national standard for labelling overfill," the institute said in a release Wednesday.

'Worrisome situation'

Politicians in Ontario are also discussing the situation for cancer patients.

"It's a very worrisome situation, obviously most worrisome for the patients and their families involved, and we will work to find out how this happened," said Ontario Premier Kathleen Wynne.

"I don't know exactly how this happened, but we obviously need to find out how it happened."

Questions have been raised about the impact the lower than intended doses of the chemotherapy drugs might have had on cancer patients and whether or not they could have lived longer with proper doses.

"What is the implication of that dilution? Does it mean it would affect the outcomes of people's treatment, their longevity," asked Ontario NDP Leader Andrea Horwath.

Both the provincial health ministry and Cancer Care Ontario have a lot of questions to answer, added Horwath.

Seeking answers

"I think this rocks people's trust in the health-care system and in the distribution of drugs in Ontario, and that's worrisome," she said.

"People need to be certain that the treatment they're receiving is the treatment that's prescribed and that it's the appropriate treatment for whatever illness or disease they happen to be battling."

Ontario Health Minister Deb Matthews said Tuesday that she doesn't want people to panic about the situation. She urged affected patients to contact their oncologists.

Cancer Care Ontario said the drugs, cyclophosphamide and gemcitabine, were watered down an estimated three to 20 per cent. The diluted chemotherapy was given to patients for at least a year in some of the hospitals.

With files from Kelly Crowe and The Canadian Press