Updated

In 1981, Scott Erdman was studying to become a pastor when he was diagnosed with melanoma. Six brain tumors and multiple systemic tumors later, he has won his battle with cancer— a feat he credits to his faith and cutting-edge medical technology.

Erdman had fought cancer for nearly half his life. At age 24, he spotted the first sign of the disease: a small lump in his armpit. Doctors removed a tumor and 24 surrounding lymph nodes, and he celebrated being cancer-free for five years in spite of a three-year prognosis.

At the time, Erdman was enrolled at Fuller Theological Seminary in Pasadena, Calif. After his diagnosis, he took off about nine months before deciding to return to school.

“I’ve always been an individual that’s really wanted the most for what I could give, and so when this happened … God really took the issue of what was going to happen with my life, and I didn’t ever really take it back,” he told FoxNews.com. “I decided to live as I could, as long as he would have me alive.”

He worked as a youth pastor at Bel Air Presbyterian Church while attending seminary, a decision that his church and school communities supported.

Then, in 1991, he began getting headaches. An MRI scan revealed three brain tumors, all in highly sensitive areas of the brain. The largest was the size of an orange.

For patients with brain metastases for melanoma, life expectancy with whole-brain radiation— the standard treatment for tumors at the time— is about a year. However, the treatment also radiates normal brain tissue, and if a patient lives beyond three years, consequences of the procedure include intellectual and memory decline, and cognitive impairment. Plus, metastatic melanoma is not sensitive to radiation, Erdman’s neurosurgeon, Dr. Keith Black, told FoxNews.com.

While in the emergency room at the University of California, Los Angeles Medical Center, Erdman first met Black, who believed he could do better than the standard treatment and opted to surgically remove the tumors. Next, Black used stereotactic radiation therapy— also known as the XKnife, a new procedure at the time— to aim X-ray beams directly at the area with the tumors.

Black noted that although Erdman ended up developing tumors again, they would’ve recurred even with radiation and the long-term consequences were not worth the risk.

“I didn’t expect removing these three tumors surgically would cure him of his melanoma— I did believe it would give him a year or two before new [ones developed],” Black said.

The surgery was successful, but Erdman began having seizures unexpectedly. The first grand mal seizure, the type that involves physical seizing of the body, occurred while he was driving. Taking anti-seizure medication hasn’t seemed to help suppress the seizures, but Erdman continues to take them as a precaution.

“It gets a little exhausting, but it’s like you don’t have an option— I  can pack it in or I can go for it. I wasn’t going to pack it in,” Erdman said.

Two years after his brain surgery, another tumor appeared. Fortunately, the imaging technology had improved enough so that doctors were able to find the brain tumor, remove it, and have Erdman out of the hospital in two days. Black followed Erdman’s health carefully with high-resolution MRI scans.

Cancer returned in 1994, and Erdman had to have his left kidney, spleen, part of his pancreas, and some lymph nodes removed.

Black, who moved to Cedars-Sinai Medical Center and is now the chairman of and a professor in the department of neurosurgery, continued to monitor Erdman, and in 2008— 14 years since his last cancer battle— found two small lesions. He operated, using Gamma Knife radiosurgery, which uses tiny beams of radiation to precisely target a tumor, and Erdman has been in remission since 2010.

Black said Erdman is among a small percentage of patients who had an initial prognosis of about a year— or less than a 5 percent chance of living two to three years— but has now lived 20 years without evidence of tumors.

“We have a number of patients like him, luckily that number is beginning to increase over time as we become more intelligent about the way that we treat these tumors,” he said.

In the last couple of years, better melanoma drugs that activate the immune system against tumors have been developed, but Black suspects Erdman’s immune system has played a part over time.

“It’s a basic tug-of-war taking place between the tumor and the body’s own immune defense,” he said. “Eventually, the immune defense got strong enough to control regrowth of microtumors.”

While Erdman is thankful for the medical care he has received, he credits his survival to one thing.

“I can tell you, the reason I’m alive is because of God, no question in my mind. I’ve got the greatest neurosurgeon the world has to offer, and I’m grateful because he’s been able to destroy tumors that others might not have been able to …  Doctors don’t think I should be here today,” he said.

Because his brain has gone through so much,  Erdman struggles with words at times and his short-term memory has weakened over the years.

“Other than the cancer itself, as it ravaged my body, I have been a pretty healthy person, and I’m grateful for that because I don’t know how else I’d be able to handle what’s going on,” he said.

Multiple studies have shown that a positive attitude has led to better outcomes in different diseases, which Black credits with Erdman’s recovery and longevity.

“I think the fact that he’s a pastor is not lost on this story, and whether you’re religious or not, one thing to me has been very clear in dealing with cancer patients, and that is the patient attitude clearly affects hormonal levels in the body and their immune system— if someone is very worried or very negative, you get a release of chemicals in the body that are unhealthy for your body and immune system,” Black said. “Whether it was his belief that he would do better, belief that divine intervention would help him do better, or whether it was actually divine intervention, obviously we don’t know, but it’s very clear that attitude makes a real difference in outcome with cancer.”

In June 2014, Erdman, now 57, retired as pastor of First Presbyterian Church of Hollywood and now hopes to support cancer patients as they go through the same journey he did.

“It made me look at myself from a whole different perspective, and I think it changed [me] totally … having gone through it, I recognize that I’m a different person today than  I would have been having not gone through it,” he said.  “I don’t know what God has for me, so I’m just trusting I’ll go with the flow and, somewhere down the line, he’ll use me as he wants to use me.”