Kevin Daly was worried that even when he lost 34 pounds, his beer belly wasn’t going away. “I don't even like beer,” he explained to the New York Daily News. “I was lean. I'm 6'3" and very athletic.”

The financial planner shed the weight in 2015 after he had open-heart surgery, but he and his wife Rachelle were baffled when his stomach didn’t go down.

The 63-year-old told the newspaper, “I thought they literally left stuffing and tools in me from surgery.”

BEFORE/AFTER: Doctors believe it took 10 to 15 years for the mass in Daly's abdomen to grow to the size it did. The 63-year old's pot belly went down following surgery. (Courtesy: Lenox Hill Hospital)

It was Daly’s persistence that may have saved him. He convinced Dr. Varinder Singh, at Manhattan's Lenox Hill Hospital, to perform a CT scan, despite the objections of his insurance provider.

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The financial planner, from Hoboken, N.J., was eventually diagnosed with liposarcoma — a rare cancer that develops in the fat cells of soft tissue.

Typically, patients can gain 10 to 20 pounds because some tumors can be very large, but a tumor in the abdomen may be tough to diagnose because patients may think they’ve gained weight, Memorial Sloan Kettering Cancer Center explains on its website.

“It’s one thing to see the picture. It’s another thing to actually have it in your hands,” said Daly’s surgeon, Dr. Julio Teixeira. (Courtesy: Lenox Hill Hospital)

“It was the largest tumor I’ve removed. It was a very challenging operation," Dr. Julio Teixeira, Daly’s surgeon, said in a statement. "Because of the tumor size, there were organs out of position.”

“It’s one thing to see the picture. It’s another thing to actually have it in your hands,” he said.

He said the tumor was nearly triple the size the surgical team expected it to be, and that it had wrapped around one of Daly’s kidneys. Doctors believe it took 10 to 15 years for the mass to grow to the size it did.

Since the surgery, Daly’s belly has gone and he said his organs have returned to their usual position. “Before the surgery, my left descending colon was pushed under my sternum. I could touch it through my skin to make my food digest.”

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For more perspective on liposarcomas, Dr. William Huang told Fox News, “As they grow, they initially displace or push away neighboring organs. However, once they reach a size that results in compression or involvement of adjacent organs, then they can cause discomfort or symptoms.”

The associate professor of Urology at NYU Langone Health added, “I remove retroperitoneal sarcomas several times a year. Most recently, a larger one in 2014, which was over 20 pounds. It required removal of the spleen, adrenal gland and the kidney. The patient is alive and without disease.”

According to the Mayo Clinic, it's not clear what causes the rare cancer, except that liposarcomas form when a fat cell develops errors (mutations) in its genetic code and grows into abnormal cells that form a mass.