This week every newspaper (that I read) featured an article that appeared in the March 17th JAMA issue. It raised questions about the reliability of breast biopsies and whether recommendations for therapy should be solely based on a single biopsy “reading”. As usual, after the attention grabbing headlines, certain details were missing (or discussed at the end) in much of the media reporting. I am going to discuss this article on my website today just to point out some of the facts that may not have been emphasized.
Let’s start with the facts we do know… Breast biopsies are performed in 1.6 million women in the United States each year. Breast biopsies are performed due to abnormalities found in mammograms, ultrasounds, MRI’s or perhaps after a physician or the woman palpated a mass. The question asked and hopefully answered with the biopsy is whether the area of suspicion is normal, has an overgrowth of glands that is abnormal (called atypical hyperplasia), has a very early cancer that has not advanced out of the duct borders (DCIS) or is invasive cancer. The researchers took a set of single glass slides from 240 breast biopsies. Three expert breast pathologists, who came from academic institutions, taught courses and wrote papers on breast pathology read the slides. What is interesting is that they agreed on the diagnosis only 75% of the time. When they looked at additional data and perhaps additional slides they were able to agree 90% of the time. Most of their disagreement came in cases where it was not clear whether there were some atypical glands or more advanced DCIS. The women whose biopsies they looked at were mostly in their 40s and most of them had very dense, complex breasts in whom biopsies are known to be quite difficult to read.
The slides were then distributed to 115 randomly selected pathologists who agreed to read them and indeed spent hours doing so in exchange for receiving continuing medical education credit (up to 16 hours). These “outside” pathologists agreed with the experts 75.3% of the time, this ranged from 96% or cases of invasive cancer, 84% for those with DCIS, 48% for atypia and 87% for benign lesions without atypia. The pathologists who were not in academic centers and/or had fewer cases to diagnose in their practice were less likely to be in consensus with the experts.
So does that mean that when a report is issued after a biopsy its relevance is questionable? This is where I get to say that no imaging diagnostic tests for breast cancer are completely accurate. Mammogram can miss cancers especially in dense breasts and breasts in young women. Ultrasound can only determine whether an abnormality is cystic or solid. MRI cannot pick up the microcalcifications there are a hallmark of DCIS. And if simply palpating the breast for masses were enough, we wouldn’t need all those imaging tests. We do however need radiographic methods to decide what to biopsy and whom to biopsy; they save tens of thousands of lives and allow for early diagnosis. But none are full proof. Dense breasts also increase the risk of pathology. So the only thing we can do is combine scanning modalities and biopsy to get the best results possible.
What most pathologists will do if there is a questionable slide or one that is difficult to read on its own is look at additional slides taken from the same specimen. They often consider clinical features of the patient and her history. They might consult other pathologists to come to a final diagnosis. None of this was part of the process in the article. But if we look at the truly invasive cancers in the study, the vast majority of diagnoses were appropriate. Additionally those slides that were read as having no pathology were also most often in concordance with the readings of the experts.
My concern is that the study showed that in 4% of the cases a diagnosis of invasive cancer was missed and there was discordance in diagnosis of DCIS 16% of the time. Even the experts did not always agree! So as the editors stated in JAMA “the study supports the value of a second opinion in cases of ambiguity.” And this is why I tell my patients that getting an abnormal biopsy is not a medical emergency that needs to be treated yesterday. Extra time, second opinions and discussion of the diagnosis and treatment should take place in a non frantic pace. Medical care is best when done with collaboration, consideration of all relevant factors and appropriate expertise…