Surgeons make different choices in how they excise abnormal cells that are an early precursor to a breast cancer called ductal carcinoma, or DCIS. And surgeons make a wide range of recommendations on whether a woman diagnosed with DCIS should receive radiation therapy after surgery.
Those physician differences, says an article published on Monday in the Journal of the National Cancer Institute, play a pretty significant role in predicting whether a woman who has been treated for DCIS will have a recurrence of the condition or a later diagnosis of invasive breast cancer. A group of researchers from the Rand Corp. concluded that variations in the way surgeons treat DCIS account for as many as one in three recurrences over five years and three in 10 over 10 years. That was the case even after the researchers took account of factors that are already known to make a difference in a woman's risk of recurrence, such as a family history of breast cancer, diagnosis at a young age, and the presence of cells known for their aggressive ways.
DCIS itself is not lethal, and between 96% and 98% of those diagnosed and treated will be alive and disease-free 10 years after getting such a diagnosis. But rates of the diagnosis -- sometimes called "stage-zero breast cancer" -- have surged with more widespread screening for and earlier detection of breast cancer. In a still unknown proportion of cases, the presence of abnormal cells in the milk ducts of the breast will, in time, become invasive breast cancer. Because it's not known which cases of DCIS will lead to invasive breast cancer, physicians almost always treat it with surgery followed, in some cases, by radiation.
But the type of surgery -- mastectomy or breast-preserving surgery -- and how wide the margins are that the surgeon cuts around abnormal cells do make a difference in a woman's risk of DCIS recurrence or of invasive breast cancer, the Rand researchers found. And so does the decision about follow-up radiation. Women with a DCIS diagnosis who underwent mastectomy had the lowest risk of recurrence or invasive breast cancer. They were followed by women who had surgery that removed cancerous cells while preserving the breast and then underwent radiation therapy. Women who had breast-preserving surgery and no radiation were most likely to have a DCIS recurrence or to develop invasive breast cancer over five to 10 years. And consistently, when the surgeon removed a margin of healthy tissue of at least 2 millimeters around abnormal cells, recurrence risk was lower than when the cut was closer.
The wide range in surgeon's standards about treating DCIS comes amid debate over whether patients are more often harmed than helped when physicians treat this precursor to cancer aggressively. And it's not clear that the latest study, which would seem to make the case for more uniformly aggressive treatment, will do anything to quell that debate.
A National Institute of Health consensus panel that met in September 2009 urged that physicians stop using the "anxiety-producing term carcinoma" in diagnosing the presence of abnormal cells in the breast's milk ducts. The panel also noted that far more research is needed to identify the women who will benefit most by aggressive treatment, as well as those whose DCIS is unlikely to develop into invasive cancer.