Breast cancer: What is DCIS and how is it treated?

One common form of breast cancer, called DCIS (ductal carcinoma in situ), has a low rate of invasiveness ‘ only 10 percent. Read about what DCIS is and why a diagnosis means you may not need to panic

Breast cancer: What is DCIS and how is it treated?

Source: Best Health Magazine, Spring 2008

Hazel Thornton was 57 years old when she answered an invitation from her local breast-screening centre in Colchester, England, to have a mammogram. As a survivor of malignant melanoma that was caught on time, Thornton believed in the value of early detection and treatment.

She had no symptoms, but her mammogram showed a form of breast cancer called ductal carcinoma in situ, or DCIS. It is a non-invasive proliferation of cells and microcalcifications confined to the lining of the breast’s milk ducts and not spread to breast tissue or other organs. While just 10 percent of DCIS goes on to become invasive, no reliable method exists to distinguish the harmless from the potentially deadly.

Women diagnosed with DCIS are advised by cancer specialists to undergo breast cancer treatment, either mastectomy if the cells are dispersed throughout the breast or, if the cells are contained in one area, a lumpectomy usually followed by radiation and/or tamoxifen. After a biopsy that confirmed the DCIS diagnosis, Thornton was put on tamoxifen.

She also began to educate herself about DCIS—and what she learned appalled her. She has since become an international advocate for better informed consent and fuller disclosure of the risks and benefits of screening mammography for otherwise healthy women. Over the past decade Thornton, formerly a businesswoman, has become a featured speaker at international medical conferences, and has published articles and reports in respected medical journals, some co-authored with leading breast cancer experts.

As far as Thornton is concerned, for most women, the early detection of DCIS is doing more harm than good. By discovering the cancer at such an early stage – before it has a chance to turn into an invasive disease (and 10 percent will) – screening mammography leads to many otherwise healthy women being labeled breast cancer victims and to undergo treatment that may be unnecessary, or even disfiguring. “Once DCIS is found, it is difficult to do nothing – most women want it out, and you are led on to have treatment,” explains Thornton. “But if it had never been found, for many women it might never have amounted to anything.”

Dr. Cornelia Baines, a professor of Public Health Science at the University of Toronto and head of Canada’s National Breast Screening Study, agrees. “My opinion remains that the DCIS diagnosis is not beneficial to women and the treatment offered can be unnecessary and harmful.”

A pivotal Canadian study led by Dr. Eileen Rakovitch found that even though the DCIS survival rate is 98 percent, women given the diagnosis suffer the same psychological stress, anxiety and fear of recurrence and dying as women with the diagnosis of invasive breast cancer.

“This means that as a doctor you spend a lot of time educating women that this is not breast cancer as we typically think of it,” says Rakovitch, a radiation oncologist at Toronto’s Sunnybrook Health Sciences Centre and one of Canada’s leading DCIS experts. Rakovitch says because of the mental impact of being labeled as having cancer, there is debate in medical circles to remove the word carcinoma from the name.

Prior to the introduction of screening mammography—mammograms given to women with no symptoms—in the 1980s DCIS was rarely diagnosed, amounting to less than 1 percent of new breast cancers. Back then it typically showed up as a palpable lump, pain, or nipple discharge. Autopsy studies of women who died of other causes showed that DCIS existed harmlessly in the breasts of about 9 percent of women, suggesting the disorder is fairly common in otherwise healthy women. But over the past 20 years, since the advent of screening mammography, the incidence of DCIS has skyrocketed, now representing about 20 percent of new breast cancer diagnoses, or about 5,000 Canadian women a year.

Christine Wooldridge of Shawnigan Lake, B.C., was one. In November 2006, at age 68, she had a screening mammogram that showed suspicious microcalcifications in her left breast. She had a second mammogram six months later that showed more concerning changes. A needle biopsy confirmed the diagnosis of DCIS. By July 2007 she had wide excision lumpectomy, removing a quarter of her left breast, followed by 16 doses of radiation. The lumpectomy left extensive scarring and disfigurement and radiation left discolouration and burn marks on her breast that weeks after her final dose was still flaking and painful.

“It has been an awful experience but there’s no way of knowing whether it would advance, so you want it gone. But sometimes I wonder, what would have happened if I hadn’t had the mammogram and waited until any symptoms arose? Would I have had a number of years before I got invasive cancer or would I have just died of something else?”

Rakovitch is leading a team that hopes to better answer those questions. Backed by a $1.3 million grant by the Canadian Breast Cancer Research Alliance, Rakovitch’s team will examine the world’s largest collection of DCIS tissue samples for markers that may help distinguish lesions that are harmless from those that may become life-threatening.

The five-year study will examine 8,000 tissue samples taken from women diagnosed with DCIS between1994 and 2003, studying not only the pathology features but the molecular features of the lesions. It will look for distinguishing features such as estrogen receptor status, proliferation of certain antibodies, calcium binding and other markers. The results will be compared to the women’s actual outcome following their initial diagnosis. It will be the first population-based study of DCIS that tries to identify the 10 percent who go on to develop invasive cancer.

“The goal is to tease out the ones that really need the intervention,” says Rakovitch, “and ultimately be able to provide the right treatment to those who need it and avoid giving unnecessary treatment to women who don’t need it.”

In future, women may be given the choice that they can confidently keep their breasts intact and simply watch and wait for any symptoms to develop.

Get an inside look at breast cancer in our Breast Cancer Blog.

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