This is a Stage 0 (not invasive) breast cancer. Today DCIS constitutes 20% of all diagnosed breast cancers. The in situ means that the cancer cells have not penetrated the basement membrane (think surrounding perimeter) of the breast ducts. This very early malignancy is now found much more frequently than in the past because of widespread mammography screening. There is probably no true increase in incidence (though we all seem to know someone who has been diagnosed of late).
DCIS usually arises in areas of ductal cells that were already somewhat abnormal and crowded together (the official terminology is atypical ductal hyperplasia). Research has shown that in many, if not most women, DCIS does not become a life threatening, invasive cancer. But no one wants to take a chance, and therapy is geared to prevent further growth and/or invasion. Ninety to 95% of DCIS is detected through mammogram….the radiologist sees clusters or linear areas of micro (teensy) calcifications. Only 5 to 10% of women who have DCIS present with a lump or nipple discharge. So don’t skip that annual mammogram after 40 (and of course, don’t miss your physical exam).
In most cases a lumpectomy and radiation will suffice for treatment of DCIS. Total mastectomy may be indicated if the tumor is large, occurs in several areas of the breast or if the margins show abnormal cells (despite attempts by the surgeon to try to “get it all out”). Mastectomy cures 98% of patients with DCIS. Women who have had a lumpectomy and radiation may have a 5 to 9 % recurrence rate of DCIS. If it is estrogen receptor positive, adding tamoxifen therapy for 5 years (a SERM which acts as an anti-estrogen on breast tissue) will decrease this already low rate by 27% and will also decrease the chance of developing invasive cancer by 48%. Other medications which block estrogen receptors (aromatase inhibitors) are also being tested for patients who have had breast sparing surgery and subsequent radiation.
I am often asked if digital mammograms are superior to those done with film. Digital imaging may enable the radiologist to see a clearer image of the breast tissue in young women or in women with dense breasts. The images are also digitally stored for evaluation and future comparison…an obvious ecologic advantage to using and storing piles of film. But so far studies have not indicated that the new “digital” makes the old “film” inadequate. About 30% of radiology laboratory facilities have gone digital.
Breast ultrasound may also increase diagnosis of DCIS in women with dense breasts when added to mammogram. We now know that if your breasts are dense the risk of cancer is increased, not just because it’s “hard to see through them” but because there seems to be more activity in the glands.
Breast MRI may become the diagnostic tool of choice in the future. It is currently extremely expensive and time consuming (for the patient, technician and radiologist), moreover, there are simply not enough machines or trained personnel to use MRI as a routine screening procedure. But in order to give full disclosure (or should I say a better image), I have to report on a recent study published in Lancet in which MRI detected 92% of DCIS lesions while mammography found only 56%.
Current indications for breast MRI imaging include women with strong family histories of breast cancer, women who are known to have a mutation in their BRCA genes, or women who have had chest radiation for Hodgkin’s disease before the age of 30. Breast MRI is also used after diagnosis of breast cancer in order to determine if the cancer (or DCIS) is present elsewhere in the same breast or the other (contralateral) breast.
In the midst of this fairly technical and scary update let me point out the good news: We are doing better than ever in our ability to diagnose DCIS. This allows us to treat and yes “cure” more women. The long term outcome is, in oncologic terms, excellent. Ten year survival with appropriate therapy is greater than 95%. So if you are due for your mammogram, breast check or have questions…let me know!