This weekend, former president Jimmy Carter announced to a Sunday school audience of about 300 that the melanoma, found in his brain four months ago, is gone.
"They didn't find any cancer at all," he said.
The news comes several months after doctors' bleak prognosis in August that Carter had weeks to live. After surgery to remove the growth on his liver, Carter underwent radiation treatment and received doses of the drug pembrolizumab, which counters the debilitating impact melanoma cells normally have on immune cells.
The treatment is so new that it's difficult to determine how lasting the changes will be. However, Carter's response has been more promising than most participants' in clinical trials. While a minority of people who undergo immune system cancer treatment respond to it, those who do can see hugely positive results.
"We do see these so-called 'complete responses' where there is no evidence of the disease. Complete responses are really good news," Louise Perkins, chief science officer for the Melanoma Research Alliance, told the Washington Post. "We don't know how long these kinds of responses might last."
Despite his diagnosis, Carter had initially refused to cancel plans to visit Nepal as part of a trip with Habitat for Humanity, the nonprofit he has been heavily involved with for the last three decades. Habitat cancelled the trip, citing safety concerns in the country that is still recovering from April's earthquake.