Why a breast cancer diagnosis isn’t always so simple

Over two years ago, Abby Howell, now 59, went for her regular screening mammogram. A radiologist said she had micro-calcifications, small bits of calcium that show up as white specks on a mammogram.

She returned to her clinic for a diagnostic mammogram, and the radiologist said she could either have a biopsy or opt for watchful waiting. Like many women, Howell decided it would be better to know what she was dealing with so she opted for a needle biopsy, a surgical procedure in which cells are extracted for review by a pathologist.

“In my case, the pathologist reported that the cells had some atypia,” recalls Howell, ’12. A surgeon she saw insisted that she have an excisional biopsy, a more invasive surgical procedure. “I work in public health, so I know how to look at evidence. I did a lot of research and decided that with this particular type of atypia, it was unlikely I had cancer.”

Abby Howell, according to UW Professor Joann Elmore, was caught up in a bind in which many women find themselves every year. In the U.S., about 1.6 million women a year have breast biopsies to evaluate abnormalities noted on either physical exam or mammography.  While some of those biopsies result in a breast cancer diagnosis, the presence of  “abnormal cells” on a biopsy does not always signify cancer.

Elmore has conducted several studies on the accuracy of breast biopsy interpretations. Her 2015 study of breast biopsies from 240 women involving more than 100 pathologists from across the U.S. provided a textbook example of the ambiguity that plagues much of our medical care.

“The diagnoses at the extremes were very reliable. Pathologists consistently identified biopsies that were totally normal and those that had invasive breast cancer. It was the biopsy cases with diagnoses in the middle range that caused the difficulty,” says Elmore. She explained that those middle categories include what’s called atypia and also ductal carcinoma in situ (DCIS). Both of these diagnoses are associated with higher risks of a subsequent invasive breast cancer diagnosis, although it is still unknown which women would actually progress to cancer if left untreated. Because of this uncertainty, most women with DCIS undergo the same types of treatment as women with early stage invasive breast cancer.

Elmore’s research questions the accuracy of these middle-category diagnoses, and thus puts the treatment plan into question. Pathologists in her study agreed about 50 percent of the time when atypia was present. With DCIS, about four out of five agreed on the diagnosis. The good news is that the pathologists reached consensus on 96 percent of cases with invasive breast cancer.

“DCIS really isn’t the same thing as invasive breast cancer, but we don’t know enough to guide these patients with certainty so it’s understandable that women often choose aggressive treatment,” she says. However, Elmore finds it troubling when women with a DCIS diagnosis are potentially having mastectomies or lumpectomies and radiation therapy when they might not need it.

When a woman receives a diagnosis of atypia and DCIS, there is usually time to pause and consider the best approach. These are not the type of cells that rapidly turn to cancer.

Elmore’s findings were reported in the Journal of the American Medical Association and call into question the idea that a biopsy always provides a woman with a definitive diagnosis. The problem in the murky middle ground where pathologists don’t agree is the risk of overtreatment: unnecessary surgery, radiation or even hormone therapy. However, it’s also true that a biopsy sample that looks benign can be cancer and the patient may find herself undertreated. Elmore noted more overinterpretation than missed cancers in her study. Interestingly, pathologists who saw a high volume of breast pathology and worked in large group practices had a higher rate of accuracy. In another study, published in the British Medical Journal, Elmore showed that requiring a second opinion can be effective in improving accuracy.

As for Abby Howell, she had a follow-up mammogram in September with the new 3-D technology. “It took me a valium to get me in there, but the mammogram was totally clean,” she says. “So, it’s been about three years now since I chose to have the needle biopsy. And I feel even more certai