Regardless of whether Herman Cain wins the GOP nomination to run for president, he has already beaten the odds: He has survived a bout of advanced colon cancer.

In 2006, Cain, now 66, received a diagnosis of stage IV colon cancer, which means that the malignancy had spread beyond his colon. In Cain’s case, doctors found a tumor in his liver, a common location for colon cancer to spread, Cain wrote in his new book, “This is Herman Cain!: My Journey to the White House.”

About 101,000 Americans receive diagnoses of colorectal cancer each year, and nearly 49,000 die annually from the disease, making it one of the most common cancers in the United States, according to the American Cancer Society. About 20 to 25 percent of colon cancers are diagnosed at stage IV.

Only about 6 to 12 percent of patients with stage IV colon cancer survive five years, according to the National Cancer Institute and the cancer society. But because of improvements in surgical techniques and the development of better chemotherapy drugs, the chances of survival rise significantly — 35 to 65 percent — if the tumor can be removed surgically, experts said.

“Nowadays, stage IV colon cancer is approached as curative in many patients,” said Khaled el-Shami, an assistant professor of oncology and medicine at George Washington University Medical Center.

Cathy Eng, a colon cancer specialist at the M.D. Anderson Cancer Center in Houston who treated Cain, agreed. In a telephone interview Friday, Eng said she could discuss the treatment and prognosis for colon cancer generally but not any details of his case because of privacy concerns.

“The prognosis is extremely good if it can be surgically removed. That is key,” Eng said, referring to the tumor. “The best way to cure the patient is to remove it surgically.”

In his book, the former head of Godfather’s Pizza dedicates a chapter to the diagnosis and treatment he received.

“In February 2006, I heard three words that could change my life forever,” Cain wrote. He described how two doctors told him he had a 30 percent chance of survival.

After consulting several doctors, Cain first underwent four rounds of chemotherapy in Atlanta designed to shrink the tumors so they could be removed surgically.

“There are some instances where we give chemotherapy up front. It allows a reduction in the tumor burden. That can be very advantageous to the surgeon and the patient. The patient will feel better if the tumor has shrunk before you take them to surgery,” Eng said.

In Cain’s case, the chemotherapy helped, but he needed another procedure known as portal vein embolization, which involves temporarily blocking blood to one part of the liver to spur the rest to grow enough so that the patient will have a functioning liver after surgery.

“This is a surgical trick to essentially induce the liver to grow beyond its normal size and allow for a surgery that leaves the patient with a decent piece of liver that can keep him alive,” el-Shami said. “The liver is a vital organ. No one can live without it.”

After that procedure worked, Cain had one-third of his colon and 70 percent of his liver removed, along with about 48 lymph nodes, he wrote. He also underwent more chemotherapy in Atlanta, completing his treatment in January 2007 .

“We sometimes give chemotherapy afterwards to reduce the risk of recurrence in the future. It’s to try to capture any microscopic disease,” Eng said.

Patients are then followed closely for about five years. If they remain cancer-free, their prognosis is excellent, Eng said.

“The highest risk of recurrence is usually within the first two years,” Eng said. “When someone hears they have stage IV cancer, they are automatically painted a bleak picture. But that doesn’t pertain to every patient. If they are disease-free five years out, the chance of recurrence is extremely thin.”

In his book, Cain writes:

“It’s been more than six years since then. And guess what? I’m completely cancer-free! Cured!,” Cain wrote. “Why was I spared against those odds? God said, ‘Not yet!’ Did it have something to do with the Lord wanting me to survive so that I might help set this great nation of ours on its own path of recovery? I had achieved what I thought was my plan in life. My journey now is God’s plan.”

Depending on the location of the tumor and other factors, some patients are required to wear a colostomy bag either temporarily or permanently. Cain does not mention that in his book. But such a requirement is not limiting.

“It is a change in lifestyle, but most patients adjust well to this change in lifestyle, and having the bag is compatible with a normal life in most patients,” el-Shami said.