AT ASBS 2017
LAS VEGAS (FRONTLINE MEDICAL NEWS) – MRI results after percutaneous biopsy for ductal carcinoma in situ (DCIS) are often unreliable, overestimating the extent of disease and leading to over treatment, investigators from the Mayo Clinic in Phoenix concluded after reviewing 54 cases.
Of the 54 women, 7 (13%) had mastectomies driven by postbiopsy MRI findings that were not indicated on final pathology, Barbara Pockaj, MD , senior investigator and surgical oncologist at the Mayo Clinic in Phoenix, reported at the annual meeting of the American Society of Breast Surgeons.
The problem is that the core biopsy needle causes inflammation, edema, and bleeding that make the lesion appear larger on subsequent MRI. Because of the study findings, “we are ordering far fewer MRIs for patients who have DCIS,” Dr. Pockaj said in an interview.
Dr. Pockaj and the Mayo radiologists had a hunch that there was a problem and were uncomfortable interpreting MRI findings after needle biopsy, but there was nothing in the literature about it. The goal of the study was to quantify the problem and “bring this issue to light,” she said.
“I feel better, now that we have this data in hand, as I counsel patients,” who are sometimes so alarmed by MRI findings after needle biopsy that they opt for mastectomies. Now, Dr. Pockaj can tell them with certainty that MRI “may overestimate the extent of disease, so we have to take MRI findings with a grain of salt,” she said.
“Surgeons should be aware that, in patients with a postbiopsy MRI, tumor size may be different than anticipated” and may adversely “affect surgical decision-making and potentially cosmetic results. Percutaneous biopsy significantly limits the ability to accurately interpret the extent of DCIS on preoperative breast MRI by overestimating extent of disease,” the investigators concluded.
Postbiopsy MRIs were performed in 38 of the 54 women (70%), and 14 women (26%) had bigger surgeries because of their MRI results.
Three women had larger lumpectomies, and 11 had mastectomies. “Three really needed it, and one maybe half way,” but the remaining seven turned out on pathology to have only needed lumpectomies, Dr. Pockaj said.
Mean lesion size on preoperative MRI was 3.6 cm while mean lesion size on pathologic specimen was 1.6 cm. Postbiopsy MRI did not significantly correlate with the actual size of the tumor specimen (r = 0.028; P = 0.921).
If the core needle biopsy shows DCIS, in many cases, “I think you can go right to surgery,” Dr. Pockaj said. MRI might still be indicted for very large lesions, suspicions of invasive disease, or very dense breasts, but, even so, the results need to be put into context with the postbiopsy changes, she said.
Women in the study were a mean of 59 years old. Most had high- or intermediate-grade DCIS. Women upgraded to invasive disease at surgery were excluded from the analysis.
There was no industry funding for the work, and the investigators reported having no relevant financial disclosures.
