When Carlos Diaz was diagnosed with colon cancer, he was in the middle of preparing his curriculum for his history classes at Hialeah Senior High.

Diaz, 57, a father and grandfather, underwent a colonoscopy in August 2009 after initially ignoring the signs of blood in his stool.

“I went in for what seemed like a simple procedure, but I never expected to see the results saying that I had stage 3 colon cancer,” Diaz said.

Diaz is one of several featured in Surviving Colon Cancer, a documentary to air at 11 p.m. Thursday on WPBT-Channel 2. The film is designed to show how the No. 2 cancer killer in both men and women is preventable with adequate screening and care.

Grace Shafir, a local filmmaker and colon cancer survivor, produced the film, which is hosted by University of Miami President Donna Shalala, a close friend of Shafir’s.

“I was happy to help Grace because it is important to show people the reality of a preventable disease,” said Shalala. “Prevention is the best medicine and early detection is absolutely critical.”

Shafir began filming after having recuperated from her own colon cancer in 2008. “I always try to be close to the people I interview, and as a survivor, I knew colon cancer was a subject I needed to address,” Shafir said.

The film features both famous and local survivors who describe their personal struggles in surviving colon cancer.

“I hope that people will learn from the film to not do what I did,” said Diaz, who ignored his doctor’s recommendation for a colonoscopy until he was 55.

Colonoscopies are suggested for both men and women at age 50, earlier if there is a family history of the disease.

Colon cancer stems from polyps in the colon, which can become cancerous if not removed. Polyps can easily be removed with laparoscopic surgery if caught early enough.

“No one knows why exactly polyps form, but it is known that most will degenerate into cancer if not removed,” said Dr. Larry Sands, chief of the division of colorectal surgery at the University of Miami School of Medicine and a surgeon at the UM Sylvester Comprehensive Cancer Center. “One of the benefits of this cancer over others is that by doing the proper screening, a colonoscopy, one would never get it. It is completely preventive.”

Fran Drescher, actress from The Nanny and a colorectal cancer survivor herself, mentions in the film, “Catch it on arrival, 95 percent survival.”

The film details the survivors’ experiences with colonoscopies, laparoscopic surgeries, and chemotherapy and radiation treatments.

“In order for the story to be real enough that people could pay attention, I had to show them what it’s like,” Shafir said. “Chemo and radiation are not nice at all.”

For Diaz, having colon cancer did involve changing his daily routine. Two weeks since his surgery, Diaz returned to teaching and continued to teach throughout his nine months of chemotherapy.

“I have this philosophy that if you stay home you only feel worse,” Diaz said. “Some days were better than others, but my students kept me preoccupied.”