SAN FRANCISCO—Women with ductal carcinoma in situ (DCIS) can be reassured that radiotherapy does not appear to increase their risk of cardiovascular disease, according to research presented here at this year's Breast Cancer Symposium. But, another study shows that perioperative MRI does not reduce the risk of recurrence in women with DCIS.
The two studies were featured in a presscast held in advance of the symposium, which is co-sponsored by the American Society of Breast Disease, American Society of Breast Surgeons, American Society of Clinical Oncology, American Society for Radiation Oncology, National Consortium of Breast Centers, and the Society of Surgical Oncology.
No Increase in Risk of Cardiovascular Disease with RT for DCIS
Recent concerns about potential overdiagnosis of DCIS make evaluation of the late effects of treatment such as cardiovascular disease (CVD) of great importance, according to the researchers, from the Netherlands. So it is reassuring, they said, that a large study showed that women receiving radiation therapy to treat DCIS had no increased risk of CVD compared with women in the general population or those treated for DCIS with surgery alone.
The study data (Abstract 58) involved 10,468 Dutch women diagnosed with DCIS before age 75 between the years 1989 and 2004: 71 percent were treated with surgery alone (43 percent with mastectomy) and 28 percent with surgery plus radiotherapy.
The first author, Naomi B. Boekel, MSc, a doctoral student in the Department of Epidemiology at the Netherlands Cancer Institute, reported that there was no difference at a median of 10 years in the risk of cardiovascular disease between the surgery-alone and the surgery-radiotherapy groups—nine percent vs. eight percent, respectively.
Similarly, no difference in diagnosis of CVD was seen between women receiving left- vs. right-sided radiotherapy—seven vs. eight percent, respectively.
She said that interestingly, DCIS survivors had a 30 percent lower risk of cardiovascular mortality compared with the general public, speculating that this might be due to lifestyle adaptation among women diagnosed with breast cancer, or conflicting risk factors between DCIS and CVD such as age at menopause, or that DCIS patients are perhaps more health conscious after a DCIS diagnosis.
The moderator of the teleconference, Steven O'Day, MD, a member of the ASCO Communications Committee and Clinical Associate Professor of Medicine at the University of Southern California Keck School of Medicine and Director of Clinical Research at Beverly Hills Cancer Institute, said that older radiation studies clearly showed a correlation between radiation and cardiovascular toxicity when the fields were overlapping over the heart.
But radiation therapy has been refined over the years, he said, and the strength of this study is that the data are relatively recent, 1998-2004, a time when more modern techniques of radiation therapy were being used.
“What's reassuring about this study is that with aggressive treatment with radiotherapy there was not an increased risk of death and no increased risk of cardiovascular death,” he said. “This study allows us to feel comfortable continuing our aggressive treatment of DCIS.”
Long-term Outcomes in DCIS Not Improved by MRI
Adding MRI to mammography before or immediately after surgery was not associated with reduced local recurrence or reduced contralateral breast cancer rates among women with DCIS treated with lumpectomy, said researchers from Memorial Sloan-Kettering Cancer Center.
Their findings, from a large retrospective study, were presented by Melissa L. Pilewskie, MD, a breast surgeon there (Abstract 57 ).
She said that MRI has a high false-positive rate, which can result in additional biopsies and delay in surgery. The report also noted that in a recent survey of U.S. surgeons, 37 percent routinely used MRI for patients with DCIS.
Among 2,321 women who underwent a lumpectomy for DCIS between 1997 and 2010 at Memorial, 596 had received an MRI either before (81%) or immediately after surgery, and 1,725 had conventional imaging alone.
After a median follow-up of 59 months, there was no statistically significant difference in five-year locoregional recurrence—8.5 percent with MRI vs. 7.2 percent without MRI. In the cohort of women who did not undergo radiotherapy, locoregional recurrence rates were about 10 and 13 percent, respectively.
There was no statistically significant difference in five-year contralateral breast cancer either, at 3.5 percent for each group. Among women who did not receive radiation, the rates were 3.5 and 4.6 percent, respectively.
Pilewskie said the difference in recurrence rates might be due to the fact that women who received MRI were younger, more likely to be premenopausal, to have a family history of breast cancer, and to receive radiation and endocrine therapy—all factors associated with higher-risk disease. These data, which were collected prospectively, along with previous studies showing that use of MRI does not decrease re-excision rates for women with DCIS, suggest that MRI is not associated with either improved short-term or long-term outcomes.
“As new technologies are used, this study grounds us to make sure we are actually making a difference,” O'Day commented. “It's not that MRI can't be used—there are cases where it is important to obtain perioperative information with the sensitivity that MRI may give—but these data suggest its routine use in DCIS is not warranted.”
Women Not Aware of Their Breast Cancer Risk
SAN FRANCISCO—In another study discussed during the pre-Symposium teleconference, more than 90 percent of women in a large-scale survey either under- or over-estimated their lifetime risk for developing breast cancer. And 40 percent said they had never discussed their personal breast cancer risk with a doctor (Abstract 4).
Jonathan D. Herman, MD, an obstetrician-gynecologist at Hofstra North Shore-LIJ Medical School in New Hyde Park, NY, described a survey of 9,873 women age 35 to 70 who had undergone a mammogram at one of 21 participating centers. The women were asked to estimate their risk of developing cancer over the next five years and over their lifetime. They were also asked for demographic information and other data that could be used to calculate breast cancer risk.
A woman's estimate was considered inaccurate if it differed from the calculated risk by more than 10 percent. Only 9.4 percent of women accurately estimated their risk; 44.7 percent underestimated and 45.9 percent overestimated the risk. Caucasian women were more likely to overestimate risk, Herman said, and African American, Asian, and Hispanic women were more likely to underestimate.
His coauthor is his teenage daughter, Sarah M. Herman, who in 2010 when she was 13 questioned her father's contention that women did not understand their breast cancer risk.
“Despite all the publicity, marches, and pink ribbons, it is disconcerting that only 9.4 percent could tell us what their breast cancer risk was,” Dr. Herman said. “We hope patients will ask their doctors what their numbers are, and that doctors will become aware of calculating risk so they can elevate the care of their patients.”
The moderator of the teleconference, Steven O'Day MD, praised the study: Decisions about how best to do surveillance and potentially use chemoprevention are difficult decisions, even when we accurately know the risks. The results—not all that surprising—show that when only 10 percent of patients know their own risk, these decisions become almost impossible. Both under- and overestimations have significant consequences.”
O'Day pointed out that the study goes hand in hand with a recent article in the Journal of Clinical Oncology (2013;31:2942-2962), with a Clinical Practice Guideline on the use of pharmacologic interventions for breast cancer risk- reduction (OT, 8/10/13 issue).
“In order to make final decision on chemoprevention, an accurate understanding of prognosis and risk, both from the patients' and physicians' perspectives, is going to be essential to making good, sound decisions,” he said.
Dr. Jonathan Herman's co-researcher, his daughter Sarah, now 16, wrote this essay to describe their research:
Breast Cancer Research Project
By Sarah Herman
For as long as I can remember I have had to listen to my father rant on and on about breast cancer. Just about two years ago, in the winter of 2010, I remember standing in my family's kitchen when he said that women should know more. They need to know their own risk numbers and they need to know their own risk factors. I could not believe it.
With all of the publicity, walks, and the pink ribbons, how could women lack this knowledge when it's so easy to have? I jumped into the conversation. I wanted to learn if it was true what my father was telling me. It was then that my project was born.
We decided to ask women what they knew about their personal risk. With a little help I put together a 25-question survey. I then went to my neighborhood radiology/mammography centers asking them to give out my survey. I was amazed when they said yes; I was all of 13 years old at the time. My goal was to collect as many as I could.
At the start I only had a couple of radiology centers giving out my survey. I was excited and encouraged when I picked-up the first 50 responses. Over the next four months, I was able to add on another radiology center and then another. I began in January and by June 2011. I had 21 centers participating. Soon enough I was receiving around 1,000 surveys a month! I could not believe how much my project was growing.
My dining room table was soon and still is covered with hundreds of surveys that I enter into the database daily. This work is not easy! After the first three thousand, I recruited a few friends, my parents and even my grandmother to help. I started high school in September. There was no way I would be able to enter them all. It's now two years into the project. There are more than 11,000 surveys entered.
As the surveys were entered, I kept an eye on the results and I have really been surprised at what I saw. I asked women, “when was the last time they spoke with their doctor about their personal breast cancer risk?” Forty percent of women replied they never have. My data shows that more than 85 percent of women either underestimate, overestimate, or way overestimate their risk of getting breast cancer.
It's true; we need to change how we educate because knowledge is power!