Medical researchers from the University of Alberta are pushing the boundaries of nuclear medicine. They are finding new ways to harness technology, new knowledge about the nature of cancer and the radioactive nature of elements to learn more about how cancer affects individual patients and improve their treatments.

X-rays, CAT scans and MRIs give two- or three-dimensional views of body structures, allowing doctors to see inside patients to identify structural abnormalities caused by disease. On the other hand, nuclear medicine uses safe radioactive materials to create images of body functions at the molecular level, particularly in patients with cancer.

The newest imaging technology combines PET scans (positron emission tomography) with CAT scans to provide a 3D “map” of metabolic activity in cells – the basic process by which cells transform glucose into energy. This diagnostic tool called molecular imaging is especially valuable in pinpointing tumours very early, for conducting cancer research into the effects of cancer on the body, and for selecting the right treatment for the right patient at the right time.

The PET Centre at Edmonton’s Cross Cancer Institute is operated by the U of A and Alberta Health Services. It is the leading centre in Canada in the research and application of molecular imaging for cancer. Several principal investigators from the U of A’s Oncologic Imaging Division in the Faculty of Medicine & Dentistry are carrying out cutting-edge discovery research at the Cross to advance the science of nuclear medicine.

These academic clinicians and scientists are also involved in many different studies using molecular imaging to “see” and learn about the behaviour of various kinds of tumour cells, and how the cells respond to experimental chemotherapy drugs and/or radiation treatments.

“We think we can use molecular imaging to predict how a tumour is going to behave and how a patient is going to respond to a course of treatment, and learn very early if the treatment is working or if it should be changed,” says Dr. Alexander (Sandy) McEwan, professor and chair of the faculty’s Department of Oncology who also leads the PET Centre.

“That’s what a lot of our research is designed to test,” adds McEwan, a molecular imaging specialist and past president of the international Society of Nuclear Medicine in 2007-08.

Molecular imaging works this way: Radioactive isotopes(unstable forms of elements)that decay quickly are combined with organic molecules to produce what is called a radiopharmaceutical. The most widely used one is FDG, which combines glucose with a radioactive fluorine isotope. After a tiny amount of this “radioactive sugar” is injected into the patient, a special camera (PET scanner) detects where it is being used in the body.

The camera takes pictures which follow the path of the radiopharmaceutical as it is processed by the body. Because cancer cells are heavy users of glucose, increased concentrations of FDG end up in tumours, making them visible.

Molecular imaging shows the tumours very well, even those too small to be detected by CAT scans alone or which don’t show up as being abnormal in CAT scans.

Since the PET Centre was established at the Cross in 2002, more than 20 clinical trials involving more than 5,000 patients have been started, using seven different radiopharmaceuticals, each measuring a specific cancer process. The PET Centre also has facilities on site to manufacture enough FDG to supply all of Alberta’s needs, as well as ship product to Winnipeg.

The U of A oncologic imaging research group is also focusing on developing new tracers using different radioactive isotopes (carbon-based instead of fluorine-based, for example), and combining them with different organic compounds to find new ways to improve cancer diagnosis and treatment.

For example, not all types of tumours will take up glucose. So a research project led by faculty member Dr. John Mercer has developed two new radiopharmaceuticals using fructose, another form of sugar, instead. The team has shown in the laboratory that breast cancer cells rapidly take up one of their fructose tracers, and will soon be testing this in patients.

The research group now has an international reputation, as demonstrated by the fact that Edmonton was selected to host the upcoming conference of the International Society of Radiopharmaceutical Sciences this July (2009). This meeting will attract over 700 researchers to the city to discuss the best ways of using molecular imaging to help patients with cancer and other diseases.

A unique tracer has been developed at the Cross called FAZA. It detects hypoxia (absence of oxygen) in tissue. If hypoxia is present, chances are patients with cervix and lung cancers will have a poor outcome. to treatment. FAZA is used as a predictor of treatment response and best treatment option. Dr. Piyush Kumar is working with FAZA in clinical trials involving patients with a number of different cancers.

Other researchers such as Dr. McEwan and Dr. Frank Wuest are studying other molecular pathways in cancer cells that can be used to target specific cancer therapies, for example how cancer cells make DNA.

Dr. Wuest, an eminent researcher from Dresden, Germany, who was recruited to the faculty in 2008 and holds the Diane and Irving Kipnes Chair in Radiopharmaceutical Sciences, is one of those who is designing new types of tumour-seeking tracers for better and earlier detection.

“As basic researchers, we are devoted to creating more specific probes that exclusively target a specific molecular process (like prostrate or breast cancer),” Wuest says. “We are very proud of our molecular probes that are already in use for treating prostate, breast and other cancers.”

Source: University of Alberta