In June 2014, Lunden beat stage two triple negative breast cancer and calls it the toughest battle of her life.
"Well, triple negative is extremely fast-growing and aggressive. I might not be sitting here talking to you if I hadn't had that ultrasound that day," Lunden said.
It was the ultrasound that saved her life only because Joan happened to have learned about dense breasts after doing a story with a doctor, on mammograms.
Former GMA co-host talks about her diagnosis and battle with breast cancer
"I had a clean 3D mammogram," Lunden said. "I wouldn't have even known to ask for that ultrasound, had I not just happened to have been sent on that story."
The battle for Joan that followed was a quest for change that took her to Washington, D.C. where she and others were at the forefront, for years, lobbying lawmakers and government agencies.
She's on a mission to educate women about their breast density status and inform them about additional tests like ultrasound and breast MRI that could potentially catch their cancer sooner.
Breast density is a known risk factor for breast cancer.
While mammograms are the gold standard, this white tissue in dense breasts can sometimes mask cancers on a mammogram.
In September, the FDA mandated new guidelines nationwide which stipulate that all mammogram results also include information about the patient's breast density.
It's a big victory in the breast cancer awareness effort, but Lunden says advocates now have a new fight ahead of them -- getting the additional tests covered by insurance.
"That would be logical. You would hope that everything was aligned, that what your doctor recommended would be covered by your health care provider," Dr. Laurie Margolies with Mt. Sinai Breast Imaging and Radiology said.
"If you don't know, call your radiology lab, and say, 'what is my breast density?'" Lunden said.
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