Increased Risk of Invasive Breast Cancer after DCIS

Over the years of my work in oncology, the standard of care for newly diagnosed ductal carcinoma in situ (DCIS) has changed and then changed again. Many years ago, women with a DCIS diagnosis were routinely treated by mastectomy even though women with invasive breast cancers were often offered the option of a wide excision/lumpectomy and radiation. It was baffling and very upsetting to be told that you have DCIS, Stage 0, and yet you need to lose a breast when a woman with Stage 1, Stage 2, or even Stage 3 breast cancer might be able to save hers.

A study published in the British Medical Journal found that the risk of women developing invasive breast cancer after an earlier diagnosis of DCIS is twice that of the general population.

It became, in another way, more confusing when many doctors began to say that DCIS "isn't really breast cancer." Yes, it is considered a condition that might evolve to invasive breast cancer, but it might not, and it is not so dangerous in the in situ stage. Again, women wondered: Why do I need so much treatment if this isn't even really breast cancer? By then, many women with DCIS were given the option of a smaller surgery and radiation, but that still feels like a great deal.

One of the continuing controversies about routine screening mammograms (and, remember, these are mammograms for women without a personal problem or history of breast cancer) has been that they often identify DCIS and lead to worries of over-diagnosis and over-treatment. The usual definition of over-diagnosis is that something is found that would not become a health risk if unfound. Given all the DCIS found on mammograms, there have even been some suggestions that many cases of DCIS can be safely managed with active surveillance rather than surgical intervention.

As an aside, my clinical experience has consistently been that women who are diagnosed with DCIS are, at least in the beginning, as anxious and distressed as women who have a diagnosis of invasive breast cancer. For most women, cancer is cancer, and they just want it to be gone.

A study published at the end of May in the British Medical Journal found that the risk of women developing invasive breast cancer after an earlier diagnosis of DCIS is twice that of the general population and that their subsequent risk of death from that cancer was 70% higher. These are sobering numbers and likely will lead to another rethinking of the treatment of DCIS.

Another conclusion of this study was that women with DCIS who were treated more aggressively, generally with mastectomy, did better than those who had a smaller surgery, presumably followed by radiation therapy. Most doctors immediately disagreed with that second finding, but it likely will cause some women to think even more about their surgical choice.

Through the years, the choice of mastectomy vs. lumpectomy/wide excision has been mostly dictated by the extent of the DCIS. If there is a small area that can be excised, most surgeons and women have been comfortable with the lesser surgery. If the DCIS is diffuse throughout the breast, and clean margins cannot be achieved, the recommendation has always been for a mastectomy. Read more about breast cancer treatment and surgery at BIDMC.