Minimally invasive breast biopsies have been regularly performed since the 1990s, affording women with suspicious findings a cheaper and less invasive diagnostic exam when compared to surgical biopsy. Even as most biopsies are benign, the potential for sampling error makes follow-up appointments an attractive option for reducing false negatives.

According to a study published in Clinical Imaging, women with a negative breast biopsy may only need annual follow-up appointments, instead of the six-month follow-ups recommended by some studies.

The retrospective study—led by Donna Plecha, MD, an associate professor at Case Western Reserve University School of Medicine—found no difference in the cancer detection rate when comparing annual and biannual follow-ups using a single institution review of core needle breast biopsy data. This research adds to the conflicting body of data on the issue, according to the authors.

“There are no standard guidelines for follow-up after a benign concordant biopsy result, wrote Plecha et al. “Given the potential for sampling error with percutaneous biopsy, some studies have shown that short term follow-up at six months is helpful in finding cancers that were missed. Others have not found short term follow-up helpful leading to increased health care cost and low cancer yield.”

The authors reviewed nearly 200 biopsies in the short-term group and about 400 in the long-term group, finding no statistically significant difference between the two. However, they did find evidence to spurt short-term follow-up in specific circumstances such as possible sampling error, a known problem of MRI biopsy.

“It can be technically challenging to ensure adequate sampling during MRI guided biopsy,” wrote Plecha et al. “Contrary to ultrasound biopsies, tissue sampling during MRI biopsies is not observed real-time. Additionally, hemorrhage and other post biopsy changes cause signal alteration that obscures the biopsy site and targeted lesions undergo contrast wash-out decreasing their conspicuity over time.”

These challenges led the authors to write that shorter-term follow-ups could be useful after MRI biopsies. Interestingly, they also stressed the dangers of following up too quickly, citing a Memorial Sloan-Kettering study that showed delaying the follow-up for at least six months was helpful to show enlargement.

Another reason the follow-up timing issue is yet unresolved is patient unreliability: Up to 30 percent of patients skipped out on their six-month follow-ups, according to a Stanford University study.