Canada's biggest cancer hospital announced plans Thursday to expand a clinic that can offer what no other hospital in this country can: same-day breast cancer diagnosis.

The rapid diagnostic breast clinic at Toronto's Princess Margaret Hospital will be able to provide a patient a diagnosis in a matter of hours instead of the more typical five-week wait.

Patients also receive an immediate treatment plan based on their diagnosis, which explains their treatment options: surgery, radiation and/or chemotherapy.

Women in Canada typically wait weeks for a diagnosis after finding a suspicious lump in their breast. But at Princess Margaret, almost 500 patients have quietly been undergoing rapid testing at the clinic as part of a pilot project that began in the fall of 2006.

The idea for the rapid diagnosis centre came from David McCready, a breast surgical oncologist at Princess Margaret. McCready had noticed that patients referred to him from Toronto and elsewhere typically waited about 37 days for a diagnosis after first seeing their doctor.

While that kind of wait does not typically compromise a patient's recovery as long as treatment begins soon after, it can cause enormous anxiety for the women who are waiting to hear if they have cancer.

Emmanuelle Gattuso, a breast cancer survivor herself, found those wait times unacceptable. That's why she and her husband, broadcasting pioneer Allan Slaight, are donating $12.5 million to Princess Margaret to create the newly named Gattuso Rapid Diagnostic Centre.

Gattuso and Slaight are now leading a campaign to raise a further $12.5 million to expand the clinic. They would like it to be able to see 750 patients in 2009-2010, with more seen every year until eventually, 3,000 patients a year could be seen in the expansion program's last phase, from 2013 to 2018.

"This extremely generous gift allows Princess Margaret Hospital to evolve its current clinical program on breast cancer diagnosis into a fully functioning Rapid Diagnostic Centre," McCready said Thursday. "Thanks to Emmanuelle Gattuso and Allan Slaight, we will be able to provide a new model of diagnosis for Toronto area women and men."

The key to rapid diagnosis is a costly piece of equipment, called the Xpress Rapid Tissue processor, which can prepare a sample of breast tissue for analysis in a matter of hours.

Other hospitals across Canada already offer ways to reduce diagnosis times. Some provide fine needle aspiration biopsies. But while those can be fast, they can also be inaccurate. If the needle is not placed precisely among the cancer cells within the breast, the biopsy can return a false negative result.

The rapid diagnosis program at Princess Margaret uses core biopsies, which take more tissue and therefore are more likely to provide a clear diagnosis. The tissue goes into the rapid tissue processor and is ready within hours for a pathologist to analyze.

The pathologist can then report the result that afternoon. The whole process from start to finish takes only six to eight hours.

For patients whose tests reveal a malignancy, a member of the hospital surgical oncology team can then offer a treatment plan right away to the patient: typically a combination of surgery, radiation and sometimes chemotherapy.

That's a sharp contract to the current process. In that scenario, a patient with a suspicious lump undergoes a biopsy. The tissue is sent to a laboratory to be prepared for analysis, which is typically an overnight process.

After the pathologist analyzes it, the diagnosis is sent to the doctor who referred the patient -- in some cases, their family physician, in others, a surgeon. The doctor makes an appointment for the patient to return for the result.

Patients who receive a diagnosis of breast cancer from their family doctor may then wait several days to weeks before they see a surgeon. The whole process can drag on for more than a month -- and much longer in some underserviced areas.