She survived 9/11. Then she survived cancer four times.

Courtney Clark never considered herself a 9/11 survivor.

Sure, she was a 22-year-old recent NYU grad blocks away from where the Twin Towers toppled over after planes plummeted into the iconic New York buildings. Sure, she was one of many Americans traumatized by the tragedy. But she had her life. Her marketing career. Her family. Her health.

Or so she thought.

Clark, 44, has been diagnosed with melanoma four times since that horrible, harrowing day – and recently found out that she's one of about 30,000 people who can directly trace their cancers to 9/11 as part of the World Trade Center Health Program. By their standard, she is indeed a 9/11 survivor.

"It took almost 20 years to even realize that it was the cause of all of these other issues in my life," Clark, now of Austin, Texas, tells USA TODAY.

Clark is a consultant, speaker and author focused on adaptability and resilience, not to mention an adoptive mother to a teenager; she can't carry biological children because of her health conditions.

"You don't always get answers and you're not always in control, and yet, sometimes, the things that you're asking for you just have to go at it a different way," she adds.

'It just disappeared in a puff of smoke'

When she arrived at work that day 22 years ago, it was empty. And work was never empty. She sat for about five minutes before a colleague and other folks came running in. They ushered her into another office across the hall because theirs didn't have a TV.

"They were saying (on the news) a propeller plane had hit the World Trade Center," Clark says. "But the guy in the office was on the phone with his boss, who was stuck in traffic on Sixth Avenue. And she was telling him on the phone as we were there, she was telling him, 'an American Airlines plane, it flew, I saw it, it flew over me.'"

She called her mom and stepdad, who were in Illinois, and told them she was fine; she was located 16, 18 blocks north.

"My colleagues and I go back down on the street. And we're standing with what feels like the entirety of New York City. Everybody is just standing, looking south and watching this happen. What we didn't realize is in this time period, that's when the second plane had hit."

She remembers one of her colleagues saying, "It feels like this is a movie set, when we're just waiting for someone to save us. And then after standing there for I don't know how long, all of a sudden, the second tower just evaporated from the sky, from where we were standing. It's like it just disappeared in a puff of smoke."

Slowly, health issues kept appearing

About four years later, she noticed she had a mole that was growing. Changing. A visit to the dermatologist confirmed her eagle-eyed skin monitoring: She was diagnosed with invasive malignant melanoma, Stage 1B-2A.

They were able to remove it surgically, only for it to recur two years later and two more times after that.

"When it came back the second time, the oncologist said, 'it's not common for it to come back, like most people get melanoma one time, and then they don't get it again, and you're being so careful in the sun, but it's not unheard of.' And then it came back a third time. And then it came back a fourth time. And it's like, 'what is going on here?'"

Her husband, Jamie, saw something on television about the World Trade Center Health Program. "He's texting me and he's like, 'what was the address of (your job)?' And I said, 'I don't know. I was right out of college. I don't know, that was so long ago.' And he said, 'Well, what was it within a mile and a half of the World Trade Center?'"

She applied to the program, and had to list details like where she worked, lived, why she spent so much time in that area of New York.

"Then I had to get all my doctors to send their information showing when I was diagnosed," she says. "So there's a latency period for every different disease, specifically, mostly cancer. If you were diagnosed with a cancer on Oct. 1 of 2001, that didn't have anything to do with 9/11. The latency period for melanoma was four years. I was diagnosed four years, two months and a week later. Turns out my body sure really likes to grow melanoma, as my oncologist says."

Plus, there was her asthma, which also cropped up after 9/11. After providing the organization with her medical details, she found out it was traceable to that day.

The organization certified her, and now she sees one of its doctors annually. Clark also gets scanned every six months at the hospital and in between a dermatologist sees her at home.

She often says, "at some point in my life, there's going to be no skin left. They're going to have biopsied it all."

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A different path to closure

Clark still visits New York. But she won't ever visit the 9/11 Memorial & Museum.

"I think that would be too much," she says, choking up as she speaks and pauses. "I've heard it's so lovely. I've heard it's just incredibly respectful and beautifully done. I don't know that that's something that I may ever feel ready to do."

For her, closure arrived in a different way: telling her story.

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This article originally appeared on USA TODAY: 9/11 survivor beat cancer four times since World Trade Center attacks