A McAllen man is proving cancer is not a setback after battling the disease three times.

Gerardo Cantu received his first cancer diagnosis when he was 4 months old. He was diagnosed with bilateral retinoblastoma, and two tumors were found in each of his eyes.

“One tumor on the right was on the optic nerve whereas the one on the left was touching the optic nerve,” Cantu recalled. “So as much treatment as I got — radiation, chemotherapy ¬— the left one couldn’t be saved."

Cantu said the loss of his left eye affected him mentally and physically.

In 2015, Cantu was just 14 years old when he received a second cancer diagnosis.

He was an incoming freshman in high school and began experiencing lower right knee pain, but the symptom was overlooked.

“They chalked it up to growing pains,” Cantu said, adding that the pain escalated to swelling on his knee.

Doctors found a tumor in his right knee, and he had to get a metal knee replacement.

“The diagnosis was rough, what he had to go through was a long and a very difficult treatment,” Yadhira Huerta said.

Huerta is a social worker at Vannie Cook Children's Cancer Clinic who met Cantu at the clinic while he was receiving treatment.

“He's always in such a good mood, always optimistic. I don’t think I ever saw him mad and he had reasons to be angry,” Huerta said. “He was literally facing mortality in the face at a young age.”

Cantu faced another setback on his 18th birthday when a painful, throbbing headache turned into a third cancer diagnosis.

“They found that there was a mass on the back of my head, that one was osteosarcoma again, so the cancer that I had in my right knee traveled to my skull,” Cantu said.

Cantu is now 23 years old and cancer free. He is pursuing a career in nursing and hoping his story of perseverance resonates with people working to achieve their dreams.

“There were people that told me that ‘you can’t do nursing cause you have cancer,’” Cantu said. “Don’t let anyone else write your story. The only person that can do that is you."

Watch the video above for the full story.