March 6, 2013 -- Mammograms are not something most women look forward to, but just like the 37 million other women who get a routine mammogram each year, Judy Valencia of Saginaw, Mich., has been vigilant about her check-ups.
"My sister had breast cancer, my mother had breast cancer and my three aunts also had breast cancer," Valencia told "Nightline" anchor Cynthia McFadden.
But when doctors saw an abnormality on one of her mammograms, they decided to biopsy Valencia's breast tissue. Based on the results of that biopsy, she was told she had cancer.
"There is no one who questions a biopsy and gets it double checked," Valencia said.
According to the American Cancer Society, more than 230,000 new cases of invasive breast cancer in women are diagnosed each year and breast cancer is the second leading cause of death in women, after lung cancer. But Dr. Elisa Port, one of the nation's leading breast surgeons who works at Mount Sinai's Dubin Breast Center, said women must absolutely get a second opinion if they have been diagnosed.
"We see patients all the time, they come in with their reports all the time and their diagnosis says breast cancer," Port said. "We pass the slides off to our pathologists, who sends me back a report a day later saying, 'don't agree, this is not cancer,' and it's very clear cut that it is not.
"That's probably one of the most critical pieces of information," she added. "That's why no one gets near an operating room until those slides are reviewed."
In 2006, Susan G. Komen for the Cure, the prominent breast cancer survivors' organization in the U.S., released a study that estimated that as much as 4 percent of breast cancer diagnoses were incorrect, meaning more than 90,000 people currently living with breast cancer may have been misdiagnosed.
Dr. Ira Bleiweiss, one of the country's leading breast pathologists, said diagnosing breast cancer these days can be more difficult because mammograms have become so much better, now able to detect smaller and smaller lesions.
While some diagnoses are straightforward, not all cancers are the same. Bleiweiss said it is a "very common occurrence" for him to be presented a slide where the tissue can seem ambiguous.
"These are things that are subject to interpretation and more expertise in making that interpretation is better," Port added.
But many local hospitals do not have specialized breast pathologists and surgeons. After Judy Valencia's diagnosis, she said she was told she had two choices: A lumpectomy to remove the cancerous portion or a mastectomy to remove her entire breast.
Panicked because of her family history, she opted for the most extreme course. She decided to have both breasts, the one with cancer and the one without, removed.
"I just wanted it to be done. I didn't want to have to worry about going through this again," Valencia said. "I was cancer-free and there was no radiation to be had or chemo. I was great."
Valencia and her husband Richard have been married for 39 years. He said he supported his wife's decision to remove both breasts.
"I watched a number of her relatives pass away because of it," he said. "That's why when she discussed a double mast that I went along with it. I would rather have my wife here than lose her."
In the months that followed, Judy Valencia said she could not get paperwork from the hospital for her insurance so she hired a lawyer. Her lawyer, Greg Bereznoff, suspected something was wrong and sent Valencia's original biopsy for a second opinion to Bleiweiss at Mount Sinai.
In Bleiweiss' opinion, Valencia never had breast cancer.
"I went to the lawyer, he said he had good news and bad news for me," Valencia said. "I said, 'give me the good news first' and he said, 'you are cancer free, you have no cancer, never had cancer.'"
So after undergoing a double mastectomy, having both breasts removed, Valencia was now being told she never had breast cancer at all. Bereznoff said it was a mistake that never should have happened.
"The pathologists at this institution had doubt about what they were looking at," he said. "When they wrote the report, they didn't have clarification. They gambled. Judy Valencia lost."
Port said there are people who are misdiagnosed based on someone not having enough expertise to know what is in front of them.
"It is important to stack the odds in your favor, putting together a team that deals with this a lot," she said. "What they eat, sleep and breathe is taking care of patients with breast cancer or think their might have breast cancer, that's how you stack the odds."
Judy Valencia's second opinion came too late, but she said she is telling her story in hopes that other people will learn from her ordeal. She is suing the hospital and the doctors who initially diagnosed her with breast cancer for damages.
"Nothing is the same," she said. "But I can hug my grandchildren and I'm here and I'm cancer free."