John McCain’s Brain Cancer vs. Jimmy Carter’s: Why Is McCain’s Prognosis Worse?

john mccain cancer jimmy carter

Getty Why is John McCain's brain cancer prognosis so much worse than Jimmy Carter's?

Senator John McCain’s treatment and prognosis appear much more dire than Jimmy Carter’s after he was diagnosed with brain cancer. Why do things look so much tougher for McCain, who is 10 years younger than Carter when he was diagnosed with brain cancer at 90? The truth is that Carter’s chances of survival initially appeared very slim too. But thankfully for Carter, a new type of cancer treatment proved to be perfectly suited for the type of brain cancer that he had.

John McCain has glioblastoma (GBM.) This cancer is one of the most aggressive types. It’s highly malignant, according to the American Brain Tumor Association. The median survival rate is two to three years, but can be as short as 14 months. For people who are diagnosed with any cancer at the age 75 or older, the lowest survival rate is 4.7 percent. But with glioblastomas, children are given the same survival rate as older adults.

Jimmy Carter’s cancer wasn’t a walk in the park, however. Diagnosed at the age of 90, he had melanoma that had metastasized and spread to his liver and his brain. He had four spots of melanoma on his brain, with each lesion being no larger than 2 millimeters. The lesions were discovered when he underwent an operation to remove the tumor from his liver.

Until recently, the survival rates for someone whose melanoma had metastasized into their brain were only four to five months.

Jimmy Carter beat those odds, thanks to a newer drug called Keytruda (Pembrolizumab.) Now he’s cancer free, a result that was once almost unheard of in patients who had metastasized melanoma. The drug was part of Carter’s treatment regimen, which included targeted radiation to his brain. He’s not cured in the classic sense, since he continues to need infusions. But MRI scans show no signs of cancer.

Keytruda is one of a series of new immunotherapy drugs that target specific cancers and are showing incredibly promising results. Keytruda targets the PD-1 and PD-L genes, which play a role in tumor detection. Last year, a lung cancer study using Keytruda was stopped and all patients were given the drug because the results were at least as good as chemo, if not better.

Could Keytruda or another type of immunotherapy be used to treat John McCain? It is unclear, unless he gets into some type of clinical trial. Immunotherapy drugs are being tested on patients with glioblastoma, but it’s not known yet if any will be as successful. In August 2016, it was announced that early clinical trials involving Keytruda and glioblastoma, and Opdivo and glioblastoma, appeared promising. In April 2017, Science Daily reported that immunotherapy for glioblastoma was well tolerated and out of the 11 patients studied, four survived for more than five years. This study was focused on immunotherapies that targeted specific proteins on glioblastomas.

At this point in time, the traditional treatment for glioblastoma is chemotherapy and radiation. McCain’s cancer was discovered while he was having surgery to remove a blood clot on Friday. His doctor said that a pathologist was in the operating room during the procedure and all the worrisome tissue was removed. However, glioblastomas can recur and McCain will need followup treatment. Whether any of that treatment might include a new type of immunotherapy like Carter received, or if that kind of treatment is even currently available for his type of cancer, remains to be seen.

 

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