You may have heard that some breast cancers vanish without treatment. Last month, a group of radiologists published results of a survey in the Journal of the American College of Radiology. The findings from 42 experts who responded are striking.
Of 240 invasive breast cancers found by screening that went untreated, zero (0) went away. Of 239 noninvasive cases (DCIS), zero (0) regressed, as reported by the breast imaging specialists in a survey. In sum, 0 of 479 untreated breast tumors disappeared without treatment, according to the radiologists who participated.
The survey respondents reported a total of 25,281 invasive breast cancers detected by screening in their practices over the past 10 years, and 9,360 cases of noninvasive breast cancer (DCIS). The survey instructed doctors to consider cancer as “untreated” when, after a biopsy performed through skin, patients with pathology-confirmed breast cancer received no surgery, radiation, chemotherapy, hormonal or other treatment. How many of these cases of invasive tumors and DCIS represent “overdiagnosis” cannot be determined.
Perhaps the fairest interpretation is that none of the 42 radiologists recalled having seen a single case of breast cancer vanish or regress without treatment.
To be sure, this is an imperfect report. It’s based on a survey with a 39% response rate, among other limitations, such as bias and selective memory. I don’t agree with some points raised in the discussion, and I’m not sure that the statement, “The authors have no conflicts of interest related to the material discussed in this article,” is true, given that they are breast imaging specialists. (One author is based at Weill Cornell, an institution with which I hold an academic affiliation.)
Yet this survey reflects a significant amount of clinical experience among radiologists who were selected based on their expertise. Fellows of the Society of Breast Imaging are not "young" radiologists, but sub-specialists who have accomplished extra work in that field. Taken together, the practices of those doctors who participated in the study provided a total of 6,865,324 screening mammograms over 10 years.
The article refers to three published reports which suggest that that breast cancer can disappear, based on various forms of indirect evidence. But I remain unaware of any direct evidence—such as by biopsy after time, or even by imaging, of a pathology-proven invasive breast cancer—that it spontaneously goes away.
Not all cases of breast cancer need treatment. I agree with most guidelines that after a certain age or condition, when a woman is more likely to die from something else, screening may do more harm than good. Some breast cancers are slow-growing and may indeed be harmless. The point here is that they don’t vanish.
I look forward to results from the COMET study. This trial looks prospectively at the consequences of observing (untreated) DCIS. But it will take a decade to generate meaningful data on the occurrence of invasive disease, metastases and survival in women with low-risk DCIS who don't get treatment after the biopsy.
For the time being, women and men with early-stage breast cancer, and physicians, should question the notion that these cancers disappear.
