DCIS: "Pre-Invasive" Breast Cancer?

By Gail Garfield Schwartz

From Advocacy News & Views

Last month (July 19, 2010) an article appeared in The New York Times about a woman who had a partial mastectomy following an erroneous diagnosis of ductal carcinoma in situ (DCIS). Her story raises serious questions for women diagnosed with or suspecting DCIS.   DCIS describes abnormal, pre-cancerous cells in the milk duct and only in the milk duct (in situ is Latin for in place).

Here in a nutshell is the story: The 49-year-old lady lived in a small town in Michigan.  She had a mammogram that showed something unusual.  At a small local hospital a pathologist who was not board certified diagnosed DCIS.  Another local pathology practice confirmed the diagnosis.  On the basis of the pathology, a quadrantectomy was performed, removing one-fourth of her breast.  Surgery was followed by radiation and chemotherapy.  Some time later, she changed doctors, and at her intake check up her new doctor discovered that she never had had breast cancer. 

As the Times wrote, up to 17 percent of DCIS cases identified by the commonly used needle biopsy may be misdiagnosed.  So DCIS may not actually total 25% of all breast cancers, as is presently believed. 

The physical and biological examination of tissue removed from a milk duct by needle biopsy is the pathology on which a clinician --whether family doctor, internist, surgeon or oncologist--- bases a diagnosis.  So this critical evaluation must be performed at a reputable organization employing very experienced breast cancer pathologists.   A pathologist who reads only 50 or 100 breast duct biopsies each year may be unable to distinguish the very fine differences between (relatively rare) invasive DCIS and harmless pre-cancerous cells. 

Believe it or not, no medical organization has must-meet standards for pathology diagnosis or experience requirements for pathologists.  The College of American Pathologists has no information on its web site (MyBiopsy.org) regarding certification requirements, although the Times reports that it will start a voluntary certification program for pathologists who read breast tissue, setting 250 breast cases a year as a minimum for certification. 

If certification is voluntary, one can expect that many pathologists with less experience than this will continue to read biopsies and misdiagnose DCIS.  For those SHARE readers who live in the New York Metropolitan Area, this is less of a problem because there are several major cancer centers here.  But wherever you live, in taking charge of your health care, you can ask for the best pathology service and you can insist that it be outside your local hospital if it is not a cancer center.  If you are willing to pay for it, you can even have your tissue sample read by two different pathologists.  Not easy to do, but maybe worth the effort and expense. 

But there is another very big question raised by this story: Are the treatments usually offered to most women with a DCIS diagnosis the best options?  The standard of care currently recommended by the National Cancer Institute, the American Cancer Society, and the National Comprehensive Cancer Network (NCCN) is mastectomy or lumpectomy.  The stated purpose of surgery is to prevent the DCIS from growing and becoming invasive.   

However by definition, DCIS is not invasive and so may not spread to the breast tissue outside the milk duct, let alone to other organs. No conclusive studies have indicated how many DCIS cases will remain harmless if left untreated, but according to the College of American Pathologists, an estimate of 2/3 is not unreasonable. The one third that might become invasive could take a decade or more to do so, and would be detected at later stages by mammograms.

In recent years, some breast cancer advocates have been questioning the need for immediate surgery for DCIS, a fact that the Times unfortunately overlooked.   SHARELeaders and the National Breast Cancer Coalition (of which SHARE is a founding member and a board member) are among these advocates. There is some evidence in research that surgery itself could actually cause DCIS to become invasive, because it might break the capsule in which the cancer cells are encased and release diseased cells to the surrounding area.  (See for example, ASCO.org. Abstract e22035, 2009.)  So one option is to watch and wait. 

Until about twenty years ago, DCIS was not normally even detected because screening mammograms were not given frequently to women under fifty years of age.  The leap in DCIS diagnoses to about 50,000 per year, and consequent rise in surgeries for younger women, is one reason why the United States Preventive Services Task Force, an independent panel, came out earlier this year against routine annual mammograms for women under 50.  (See Executive Director's Blog and my blog on screening mammograms)

So here's what I want to know:  Since DCIS is defined as Stage 0 or noninvasive cancer, why is the scary word "Carcinoma" even in the definition of the condition?  Why is the word "pre-invasive" used by medical organizations as if it were a sure thing that DCIS will become invasive? 

Let the medical organizations find some other label like "Abnormality." More important, let them show the clinically valid reasons for treating DCIS the same way as invasive cancer is treated.  Breast cancer advocates, survivors, and people at risk should be on the lookout for over-diagnosis leading to over-treatment.

Posted August 13, 2010.