The question of tumor margins and breast preservation after lumpectomy has persisted among oncologists for many years. Several years ago, after a meta-analysis, national guidelines emerged that said “no tumor on ink” should be the standard for women with invasive cancers. For many that guideline was controversial.
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“For years, oncologists have accepted margins larger than that, two millimeters, five millimeters, and so on.” says Chirag Shah, MD, associate staff and Director of Clinical Research in the Department of Radiation Oncology.
With this in mind, Dr. Shah and colleagues recently conducted a new meta-analysis with stricter criteria for acceptability and quality of evaluable studies.
“The challenge that we as oncologists face,” Dr. Shah says, “is how do we come up with a guideline that allows for us to minimize the need for re-operation over and over again to get new margins but at the same time not impact the risk of recurrence?” Results of his analysis were presented recently at the 2017 San Antonio Breast Cancer Symposium.
More studies included
Dr. Shah and his colleagues analyzed 38 studies, which included 55,302 patients treated from 1968-2010. They excluded two studies included in the previous meta-analysis and added seven new studies not included in the previous meta-analysis.
They also only looked at patients with a minimum follow-up of 50 months, cases with explicit pathologic criteria for defining margins, and those with consistent endpoints associated with local recurrence.
The median follow-up was 7.2 years overall, and the median age of the cohort was 55 years. Seventy-four percent of patients had T1 tumors (less than two cm), and 72 percent were node negative. The crude rate of local recurrence for patients with positive margins was 10.3 percent, compared to 3.8 percent for those with negative margins defined as no tumor on ink or wider (P < 0.001).
The crude rates of local recurrence decreased as the margin distance increased: 7.2 percent for patients with margins > 0 to < 2 mm, 3.6 percent for margins of 2 to 5 mm (3.6 percent), and 3.2 percent for margins wider than 5 mm (P < 0.001 for each).
Need for randomized trial
The analysis of Dr. Shah and his colleagues concluded that “no tumor on ink” was not an optimal guideline and recommended margin widths of at least 2 mm.
“I think the question that we raised is that two meta-analyses, one with slightly larger numbers of patients, demonstrated different results,” Dr. Shah says. “That shows the data being used to create the meta-analyses are probably not as good as you’d like them to be. More than anything this suggests we need to re-evaluate — conduct a randomized or large prospective trial — and in the interim accept a larger margin cut-off until we know for sure what the optimal margin is.”