While hearing those four dreaded words changed her life, Heinz said she remained calm and did not cry.
"It was all right, funny enough partially because I know my doctor very well ... and I ask her a lot of questions. So in a sense I was being a clinical person there looking at myself," Heinz told "Good Morning America's" Robin Roberts.
Heinz's doctor explained that she had cancer in both of her breasts and would need two lumpectomies followed by targeted radiation.
But Heinz has summoned strength to push through difficult times in the past. As the wife of Sen. John Kerry ,D-Mass., she has been through countless political campaigns in which she was publicly rebuked for her occasional candor, and in 1991 her first husband, Sen. John Heinz, died in a plane crash.
Kerry, who survived prostate cancer, said he knew his wife had enough strength to overcome breast cancer.
"Her nickname among a lot of her friends is 'Doctor T.' So, she started, as she has done for other people, doing for herself or just going after the information and finding out what the options were and making some decisions pretty quickly," Kerry said.
Heinz believes in informed decisions, especially when it comes to medical procedures.
"I like to do that. You know, I do that with kids. ... in retrospect, you know, if I had been born today, I would have been a doctor," Heinz said.
Elizabeth Edwards, the wife of Kerry's former vice presidential running mate John Edwards, has also received medical advice from Heinz following her diagnosis of breast cancer.
Heinz said Kerry reached out to Elizabeth recently following the news her husband is the father of his former mistress's baby.
"I think [she is doing] all right," Heinz said of Elizabeth.
Heinz on the First Lady's First Year
Heinz came within three points of becoming first lady following her husband's failed bid for the presidency in 2004.
She said being first lady is "tougher for a younger person, especially an intelligent, younger person because they haven't been around as long.
"She's very wise and I don't envy her job right now [during] such a tough time globally. But she's young enough and has enough stamina and strength to be a very important support to her husband," Heinz said of Michelle Obama.
Heinz is passionate about health care. For the past 14, years she has organized conferences on women's health and environmental issues.
She said she is "very disappointed that not more got done" on the health care legislation.
"I mean, if they don't like the government, don't come to Washington. Try and govern. Try and find solutions that are acceptable, that's how you get things done. And, you know I said to my husband the other day. I said, 'You know, maybe it's a good thing that we have one less seat because now the argument can no longer be a 60 seat,'" Heinz said.
That lost Senate seat was a blow to Democrats across the country. Last week Scott Brown and the Republican Party upset Democratic candidate Martha Coakley in the bid for the late Ted Kennedy's seat.
Heinz believed the challenges facing this country affected the outcome in Massachusetts.
"I think it's legitimate fear and or anger that things aren't fast enough partially based on the fact that the problem is so huge and vast -- what we inherited in this country -- and people don't quite understand either the depth and the ramifications in spite of the president explaining it," Heinz said.
Heinz described Brown's campaign style as "very open and relaxed and outgoing" while Coakley, was a "very capable person [and] very good attorney general ... [but] didn't come off anything like she should have or could have."
'Doctor T's' Advice to Women
Regardless of the outcome of the health care debate, facing cancer has emboldened Heinz's desire to help others who face similar challenges.
She says women must "be informed of where to go, how to go, what are your rights, or how to access [care]," Heinz said.
"You have to [pay] attention," she added.