Frank Thomas of Brooklyn, New York, has a new lease on life — and a powerful message for all.

That's after he beat a rare tissue cancer and a devastating heart failure diagnosis.

A New York City Police Department detective for 23 years and a father of three, Thomas told Fox News Digital exclusively that he thought "he was pretty much done" when he was diagnosed with angiosarcoma — a cancer that forms in the inner lining of blood vessels and lymph vessels, according to the National Cancer Institute. 

Angiosarcoma patients have a small likelihood for survival, experts say.

"I thought I was going to not see my kids grow up and my biggest fear was that they wouldn’t remember me," Thomas, 56, told Fox News Digital.

A decade before his cancer diagnosis, Thomas aided in the recovery efforts at Ground Zero in the aftermath of the 9/11 World Trade Center attacks on American soil.

Frank Thomas, a former NYPD detective and a 9/11 responder, exclusively told Fox News Digital about his journey from cancer to heart failure — and to his new life as healthy 56-year-old family man.

Frank Thomas, a former NYPD detective and a 9/11 responder, exclusively told Fox News Digital about his journey from cancer to heart failure — and to his new life as healthy 56-year-old family man. (Thomas Family)

"It was a horrible day and I saw things that day that I would never want anyone to see," Thomas said.

He added, "I saw firsthand the greatness and kindness of people. I also saw how evil can destroy, but then as a country, how remarkable we are. 9/11 is a very sad day for my family."

"We not only relive the events of that day as New Yorkers, but we reflect on our friends who have since passed or gotten sick and my own health challenges from 9/11," he said.

Thomas’ cancer led to a massive tumor, and his lung collapsed during a removal of that tumor. After four rounds of chemotherapy followed by radiation, he was in remission. 

"I thought I was going to not see my kids grow up and my biggest fear was that they wouldn’t remember me."

— Frank Thomas to Fox News Digital

Then, last year, Thomas was retaining water in his body and was having trouble walking — symptoms he thought might have been pointing toward COVID-19.

He was reluctant to see a doctor, so his wife of 28 years, Joan, did research and found a heart failure specialist at New York’s Mount Sinai Hospital.

"With the cancer, it was scary because the kids were little and it was a very rare type of cancer," Joan Thomas told Fox News Digital. "Ten years later we're dealing with the heart and [we’re] once again back to Mount Sinai. We listen to the amazing team of doctors and [Frank] did what he needs to do."

‘An angel on my shoulder’

Cardiologist Dr. Anu Lala diagnosed Thomas with severe heart failure in 2021. Thomas underwent several stenting procedures to relieve artery blockages. Ultimately, he and his cardiologist both credit his lifestyle changes for improvements to his heart health.

"His heart muscle function, normal being on the order of 55 to 65 percent, was written at a level of less than 15 percent," Dr. Lala told Fox News Digital about Thomas’ once-declining health status.

"Not only did I feel like I had hope to live a good quality of life, but she inspired me to want to do that."

— Frank Thomas about working with his doctor at Mount Sinai

"The heart was taking a toll on his entire body," she added. "Your mental, emotional and spiritual state is also significantly impacted. To me, this is also a reminder of how intertwined the aspects of well-being are."

The cardiologist said she tried to empower Thomas to improve his heart function, rather than focusing on the negativity associated with the words "heart failure."

Thomas said that prior to working with Lala, he was getting only four to five hours of sleep. Meals consisted of pizza and other fast-food choices.

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"I really wasn’t living in a good way where I was taking care of myself," Thomas said. "I was eating the wrong foods. I’ve taken more of a hands-on approach to what I eat now, the way I exercise … I didn’t exercise much prior."

Frank Thomas said his diagnoses impacted his family — and led to a now-healthy lifestyle. He shed about 100 pounds.

Frank Thomas said his diagnoses impacted his family — and led to a now-healthy lifestyle. He shed about 100 pounds. (Thomas Family)

"Now, I watch everything that goes into my body," he added. "I’m eating more organic food now, low fat, low calorie, a lot of vegetables, fruit … getting enough sleep."

Thomas is living an active lifestyle — exercising, traveling and walking. Before this, he was unable to make it up a flight of stairs.

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Once weighing close to 300 pounds, Thomas said that today he's down roughly 100 pounds.

Thomas’ heart failure is now in remission.

"Dr. Lala is an angel on my shoulder," Thomas said. "Not only did I feel like I had hope to live a good quality of life, but she inspired me to want to do that."

Family ‘means everything to me’

With his health in good standing, Thomas is now focused on living for his wife Joan and their kids, Emily, 24, Francis Thomas, 20 and Joseph, 11.

Thomas reflected on recent memories he would have otherwise missed. He participated in a 9/11 relay at the U.S. Naval Academy in Annapolis, Maryland, with his son Francis — whom Thomas said is "carrying that torch for the next generation."

In this family photo snapped in 2019, Frank and Joan Thomas of Brooklyn, New York, celebrate their youngest son Joseph's First Holy Communion.

In this family photo snapped in 2019, Frank and Joan Thomas of Brooklyn, New York, celebrate their youngest son Joseph's First Holy Communion. (Thomas Family)

"It was moving for me because my kid is really aware and [cognizant] of the events of 9/11," Thomas said of Francis, who attends the Naval Academy. "He’s a very caring individual. He wants to help in any way that he can — other people too, not just me."

During the memorial relay, the American flag is run for 24 hours.

"My son ran the last leg with some of the commanding officers of the Naval Academy," Thomas said. "It was a very proud moment for me. In front of Bancroft Hall, World Trade Center first responders stood up there on the stairs. I was there when my son ran the flag in, a moment I’ll never forget."

Francis Thomas, 20, son of 9/11 responder Frank Thomas, carried the American flag to Bancroft Hall at the U.S. Naval Academy in Annapolis, Maryland, during a 9/11 memorial relay event on Sept. 11, 2021.

Francis Thomas, 20, son of 9/11 responder Frank Thomas, carried the American flag to Bancroft Hall at the U.S. Naval Academy in Annapolis, Maryland, during a 9/11 memorial relay event on Sept. 11, 2021. (Thomas Family)

With Thomas’ cancer and heart failure both in remission, his wife Joan said she’s ready to retire in order to spend more time as a family. She's worked for 35 years in education. 

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Frank has "had an opportunity to watch both of his older children graduate high school and he’s going to see his daughter graduate law school," Joan said. She added later, "He’s been able to see so much of their lives."

‘Don’t wait — go see a doctor’

Frank Thomas offered tips for anyone experiencing health struggles.

"When you feel that there’s something wrong early, go see the doctor early," he said. "Don’t wait. If you’re not feeling 100 percent, you’re not feeling that well, go see a doctor."

Thomas said he’s grateful for the support from Joan and their children.

"I have an amazing wife and a very strong family. I wake up each morning happy to be here."

— Frank Thomas

"My prognosis was not good, but my wife would not accept any outcome other than fighting it with everything we have," he later added. 

"I was not living the healthiest life as I had worked nights my whole career, and I was not always eating the best food. I have learned that the blockages were a combination of that lifestyle and the radiation that was used to save my life." 

With his cancer and heart failure in remission, Frank Thomas is now focused on living for his wife Joan and their kids — Emily, 24, Francis, 20, and Joseph, 11.

With his cancer and heart failure in remission, Frank Thomas is now focused on living for his wife Joan and their kids — Emily, 24, Francis, 20, and Joseph, 11. (Thomas Family)

"As far as my mental health, I am good," Thomas said. 

"I have an amazing wife and a very strong family. I wake up each morning happy to be here. My saying is, ‘It is what it is.’ I get nervous when there are medical tests or my cancer check-up."

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"But I know that I am living the fullest life I can for as long as I can," he said.