Physicians know it. Researchers know it. Breast cancer patients learn it quickly after diagnosis.
Tumor cells with lots of HER2 glow under positron emission tomography scanning. (Image courtesy of Joanne Mortimer)
Cancer isn’t one disease with one cure for everyone. It’s more complicated and depends on the patient’s genetic profile and the biology of the cancer.
A recent study suggests that there may be as many as 10 types of breast cancer. That helps to explain why some treatments don’t work against breast cancer, even when they seem like they should.
A patient whose breast cancer is HER2-positive — that is, it expresses a lot of a protein called HER2 — is often treated with the drug Herceptin, which specifically targets HER2. But some HER2-positive patients don’t respond to Herceptin. There’s currently no easy way to tell in advance whether the drug will work for each HER2-positive patient.
So how can a woman avoid the side effects and cost of the drug if it’s unlikely to work — and choose a drug that might fight her cancer better?
Joanne Mortimer, M.D., director of City of Hope’s Women’s Cancers Program, is working on a diagnostic test to help identify HER2-positive patients who do and do not benefit from Herceptin treatment. Mortimer, together with her colleague James Bading, Ph.D., in the Department of Cancer Immunotherapeutics and Tumor Immunology, are using an imaging tool called positron emission tomography, or PET.
PET scanning uses small amounts of radiation to help doctors spot cancers in the body and see how they function.
In their study, Mortimer and Bading use Herceptin that has been tagged with harmless radiation. Doctors inject the Herceptin into the patient. If the patient’s tumors need HER2 protein to grow, the radiation on the tagged Herceptin will light up the tumors on the PET scan.
That lightbulb “aha!” moment may be a good indication that Herceptin treatment would benefit the patient. It might also identify other patients who possibly could benefit from Herceptin treatment even though their cancer doesn’t seem to be HER2-positive.
Most importantly, it also may identify those who wouldn’t benefit from Herceptin, so they could move on to other treatment options sooner.