MONDAY, May 9, 2005 (HealthDay News) -- If left untreated, a low-grade pre-cancerous condition that strikes only the milk ducts of a woman's breast may -- over the course of decades -- develop into invasive breast cancer, a new study warns.
This increase in risk applies to approximately 40 percent of women unaware they have or have had this non-invasive condition, known as low-grade "ductal carcinoma in situ" -- or DCIS.
"We've made it clear that the risk of this pre-malignant lesion becoming invasive extends over a long period of time," said Dr. David Page, the study's senior author and a professor of pathology and epidemiology at Vanderbilt University in Nashville, Tennessee. "If you don't remove it, two to 20 years later [DCIS] may become a real cancer."
The abnormal cells that characterize DCIS are confined to the lining of a channel in ducts that carry milk through the breast to the nipple. The condition is highly curable through surgical removal of the affected tissue and, in some cases, radiation.
Though typically symptom-free, low-grade DCIS is readily detectable using a routine mammogram, the study authors said.
Reporting in the June 15 issue of the journal Cancer, the research team from Vanderbilt Medical Center noted that in the 1950s and 1960s -- before the advent of mammograms -- spotting this low-grade condition was simply not possible. That means many women seeking medical care at the time may have been improperly diagnosed as healthy, despite the presence of low-grade DCIS, the researchers said.
Page's team sought to determine the long-term risks posed by DCIS. The researchers conducted an analysis of nearly 12,000 breast tissue specimens obtained from patients treated between 1950 and 1968. The researchers isolated 28 women with low-grade DCIS that had gone undetected at the time of their medical exams.
They found that 11 women -- or nearly 40 percent -- did go on to develop invasive breast cancer in the specific area of the breast affected by DCIS.
Invasive breast cancer diagnoses were made in seven of the women within 10 years after the first tissue biopsy. An eighth woman was diagnosed within 12 years post-biopsy. The remaining three women developed invasive breast cancer 23, 29, and 42 years post-exam, respectively, the study found.
Page and his team noted that of the 11 invasive breast cancer patients, four died within five years of their invasive breast cancer diagnosis. One woman died within seven years.
Breast malignancy is the second leading cause of cancer death for U.S. women, according to the American Cancer Society. In 2004, nearly 216,000 women were diagnosed with the disease, with more than 40,000 dying from it.
Based on their findings, the Vanderbilt researchers conclude that women with untreated pre-cancerous cells in their milk ducts are at elevated risk for invasive breast cancer -- an increase in risk that may span decades. Women with DCIS appear to be at highest risk within 15 years of the onset of the condition. Beyond that period, the risk persists but declines slightly, the researchers added.
There is a silver lining to these findings, however: With mammogram screenings better able to pick up DCIS, most women today can eliminate DCIS-related risk through localized removal of the diseased tissue, the researchers said.
Page emphasized that spotting DCIS early should be seen as an opportunity for timely preventive care. "Yes, these lesions can kill people, but not very many, and you have a long time to get them out," he said. "It is not an emergency situation."
Dr. Sandra M. Swain, chief of the cancer therapeutic branchs for the Center for Cancer Research at the National Cancer Institute, concurred.
"This study shows that it still could take quite a while for DCIS to become invasive," she noted. "And so I don't usually call this a cancer. I call this a non-invasive disease, a precursor, because people have a lot of irrational fear with that word [cancer]. So I try not to use it. I describe it as 'abnormal cells' -- that if you don't do anything about could become invasive cancer. But right now, it's not."
Swain said the key is to get a mammogram, get the diagnosis, and get the low-grade DCIS removed.
Of course, timely DCIS detection relies on women getting a mammogram in the first place. But a second study in the same issue of Cancer finds that's not always a given, especially for low-income women.
Between 1998 and 2000, Ohio State University researchers interviewed nearly 900 women living in rural North Carolina. According to the survey, about 40 percent of the women appeared either uncertain or misinformed when it came to their health plan's coverage of regular mammography, and more than half said that having to pay for a mammogram themselves would keep them from getting the potentially life-saving scan.
For more on DCIS, visit the National Cancer Institute.