The median survival rate for patients undergoing treatment for the aggressive glioblastoma tumor is 14 months, according to a study by the American Brain Tumor Association (ABTA).
Sen. John McCain, 80, was diagnosed on July 19 with glioblastoma, a type of cancerous brain tumor, by doctors at the Mayo Clinic.
Glioblastomas are malignant and cancerous. The cells from these tumors reproduce rapidly because they are supported by a large network of blood vessels, according to ABTA.
McCain had malignant tumors removed in 1993, 2000, and 2002, but none were invasive.
Some 30 percent of patients who undergo treatment can survive for up two years. A 2009 study found that almost 10 percent of patients can survive for five years or longer.
On July 14, doctors removed a blood clot from McCain’s brain. When samples from that surgery were sent to a lab, tests confirmed that the senator had the glioblastoma tumor.
CNN’s chief medical correspondent Dr. Sanjay Gupta said that the operation McCain underwent was significant, explaining that a part of the bone underneath the senator’s eyebrow had to be removed and later put back.
Treatment for the tumor usually includes radiation and chemotherapy. Glioblastomas are particularly difficult to treat because they are composed of many different cells. A specific treatment may work on some cells, while others remain unaffected.
The first step of treatment is removing the tumor, which has already been done for McCain. Glioblastomas can be very difficult to remove completely because they have finger-like tentacles that spread into healthy tissue.
McCain’s doctors discovered a blood clot during a routine exam last week. The senator has a history of skin cancer, so he undergoes routine checkups every four months. McCain’s doctor told CNN that the senator arrived at the clinic before 8 a.m. on Friday and looked good.
McCain told the doctor that he has felt fatigue and at times experienced double vision, which prompted the doctor to conduct a CT scan. McCain had already left the hospital when the results came in. The doctors called him back in for the surgery.
After the surgery, McCain showed no sign of cognitive delays. The doctors released him to recover at home on July 15.