Good Question: Why Are Some Cancers More Aggressive Than Others?
MINNEAPOLIS (WCCO) -- This week, doctors diagnosed Senator John McCain with an aggressive form of brain cancer called glioblastoma. According to the American Brain Tumor Association, only 10 percent of patients live five years with that diagnosis. That's compared to 90-percent of patients with breast cancer and 65-percent with colon cancer, according to the National Cancer Institute.
So, why are some cancers more aggressive than others? Good Question.
"In general, it's a biological question," says Dr. John Trusheim, a neuro-oncologist with Allina's Givens Brain Tumor Center.
He says, first, glioblastoma is a fast-growing tumor that wants to grow into the brain, which makes it difficult for surgeons to remove it without hurting the patient.
It's also not usually found until the tumor is big enough to give telltale symptoms. Patients with pancreatic, lung and ovarian cancers are also more likely to discover those cancers at later stages.
Dr. Trusheim says colon and breast cancers, ones with higher survival rates, are often caught earlier.
"Colon cancer can be without symptoms, but everyone knows to check for colon cancer," he says. "The other end of the spectrum, we can't take everyone's MRI of their brain every six months or we cannot give everybody ultrasounds of their pancreas every year."
How a cancer responds to treatment also makes a big difference. Dr. Trusheim uses pediatric leukemia as an example of how a treatment works well. Decades ago, many children died of leukemia. Now, the 5-year survival rates are between 65-percent and 80-percent.
"Those tumors are clones, each tumor is identical to the next, if you can figure out how to kill those cells, you kill them all," he says.
Dr. Trusheim also says how much research is done on a particular cancer can also affect survival rates. He says it's very slow in glioblastoma and pancreatic cancer, but researchers are making strides with immunotherapy and finding genetic similarities among cancers.
"You have to have the right luck, a little bit, you have to have a good, aggressive approach to many of these things," he says. "It's very important that everyone is treated individually."