Hector Hernandez’s belly began to grow about five years ago, and, as many of us would, he chalked his changing body up to weight gain.

Yet despite dieting, his abdomen continued to grow. The rest of him stayed slim.

Finally, in June of this year, the Downey, California, resident sought medical help. After undergoing a CT scan, he was diagnosed with a type of cancerous tumor called retroperitoneal liposarcoma.

Dr William Tseng, a sarcoma expert and Professor of surgical oncology at the University of Southern California’s Keck School of Medicine, soon took over his case.

“Sarcoma is a complex disease,” Tseng said in a USC press release. “There are 50-70 different subtypes, each unique, and they can develop anywhere in the body. Because it is so complex, you want to make sure you see a sarcoma specialist who has in-depth knowledge of the disease. I was also fascinated because on top of that, it’s a very rare disease, so it doesn’t get a lot of attention. Sarcomas make up just 1 percent of cancers in adults.”

Liposarcomas are among the largest malignancies that may develop in the human body. The masses, which form from fat cells within connective tissue, often grow to 30 pounds or more.  Though they may occur in nearly all areas of the body, liposarcomas are most prevalent in the thigh and abdominal cavity. The term retroperitoneal refers to the location of the tumor outside and/or behind the peritoneum, the membrane within the abdomen that surrounds, connects and supports many organs

In July, Dr Tseng removed Hernandez’s mass during a complicated, six-hour operation.

“You’re working all the way around and on either side of the tumor,” Tseng explained of the procedure. “You really have to think about the disease, what adjacent organs or vessels you can remove safely and what is best for the patient in terms of long-term outcomes and quality of life.”

The total excised tumor tissue weighed 77 pounds. And after a week of recovery, Hernandez had lost 100 pounds, according to CBS News Los Angeles.

Because cancerous cells had not spread (about 90 percent of retroperitoneal liposarcomas never metastasize), Hernandez did not require chemotherapy or radiation, but he will have to be monitored for tumor recurrence in the same area. Data collected from multiple studies show that patients who undergo complete resection of the primary tumor have a 54-70 percent overall survival rate, but 41-50 percent of these patients will demonstrate a recurrent mass in its place within 5 years after surgery.

As of now, Hernandez is reported to be in good health, enjoying his newly slim frame.

“It was very gratifying to see his before and after photos and see him back at the size he was four or five years ago,” Tseng said. “To be able to take it out safely and see him enjoy a good quality of life after, that’s a big thing.”