Many women diagnosed with a precancerous breast lesion known as ductal carcinoma in situ (DCIS) face a low risk of a recurrence or developing invasive breast cancer, says a study in the Journal of the National Cancer Institute.
The diagnosis can cause anxiety in women, but researchers say not to worry so much.
"Many of these women are living as if they're waiting for the other shoe to drop," says lead researcher Dr. Ann Partridge, an oncologist at the Dana-Farber Cancer Institute in Boston.
DCIS involves abnormal cells in the lining of the breast duct that have not spread outside the duct, according to the National Cancer Institute (NCI).
In 2006, DCIS accounted for more than 20 percent of all diagnoses linked to breast cancer in the US - about 62,000 cases.
Experts say the increasing percentage of DCIS diagnoses over the last 20 years or more has been attributed to improved detection from the increasing use of screening mammography.
The study notes that 28 percent of the participants "believed that they had a moderate or greater chance of DCIS spreading to other places in their bodies, despite the fact that metastatic breast cancer actually occurs following a diagnosis of DCIS less than 1 percent of the time."
The study included nearly 500 women newly diagnosed with DCIS.
"In the complex treatment decision-making process, it is often possible to lose sight of the fact that DCIS poses limited risks to a woman's overall mortality," the study authors note.
Nevertheless, approximately 39 percent of women surveyed thought they had at least a moderate risk of getting an invasive breast cancer over the next five years, and 53 percent reported "intrusive" or "avoidant" thoughts about DCIS.
That number declined to 31 percent 18 months after diagnosis, the researchers say.
Among the 487 study participants who were newly diagnosed with DCIS, 34 percent had undergone a mastectomy, 50 percent had radiation therapy, and 43 percent reported taking tamoxifen to reduce their chances of breast cancer.
The type of treatment or combination varied by surgeon, hospital volume, and geographic region.
"Although decision-making about treatment is complex, there is little doubt that women will be limited in their ability to participate in informed decision-making if they harbor gross misperceptions about the health risks they face," the authors say.
Researchers found a "strong relationship between distress and inaccurate risk perceptions."
One of the difficulties of such measures of anxiety about DCIS is that the study did not determine what these patients had learned from their physicians or from other sources - such as the Internet - about DCIS, and how accurate that information was, says Michael Stefanek, Ph.D., of the American Cancer Society (ACS).
The choice of treatment depends upon the characteristics of the patient and the lesion, adds Dr. Partridge.
The dilemma posed by the prospect of under- or over-treating DCIS is complicated by medicine's current inability to distinguish between "good actors and bad actors" - lesions that do not recur or go on to become invasive breast cancer and those that do, she adds.
Another expert agrees with that assessment.
Everyone would be more comfortable if there was not such a "big gray zone" between what is normal tissue and what is invasive cancer, says Dr. H. Gilbert Welch, at Dartmouth Medical School.
Dr. Welch argues that as mammography continues to detect smaller and smaller DCIS lesions, there can be a tendency to over-treat.
He recommends that the diagnostic threshold for DCIS be raised to doing biopsies on only lesions that measure 1 centimeter or greater in diameter, which is about four-tenths of an inch.
"There is this ironic finding that women with this early precursor lesion may be treated more aggressively than women with invasive breast cancer," he says.
"They may have mastectomies instead of just a lumpectomy. At some level we have to say, 'Does this really make sense?" he asks.
Always consult your physician for more information.
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It is important to remember that a lump or other changes in the breast, or an abnormal area on a mammogram, may be caused by cancer or by other less serious problems.
To determine the cause of any signs or symptoms, your physician will perform a careful physical exam that includes a personal and family medical history as well as determining current overall health status.
In addition, an examination may include the following:
palpation - carefully feeling the lump and the tissue around it - its size, its texture, and whether it moves easily. Benign lumps often feel different from cancerous ones.
nipple discharge examination - fluid may be collected from spontaneous nipple discharge and then sent to the lab to look for cancer cells. Most nipple secretions are not cancer, as an injury, infection, or benign tumor may cause discharge.
For women who are at high risk for breast cancer, a procedure called ductal lavage may be used. Ductal lavage is a procedure that collects cells from inside the milk ductal system - the location where most breast cancers begin.
In addition to a physical examination by your physician, an imaging test will be performed. Imaging tests may include one or more of the following:
digital mammography (Also called full-field digital mammography, or FFDM) - a diagnostic mammogram is an x-ray of the breast used to diagnose unusual breast changes, such as a lump, pain, nipple thickening or discharge, or a change in breast size or shape.
A diagnostic mammogram is also used to evaluate abnormalities detected on a screening mammogram. It is a basic medical tool and is appropriate in the workup of breast changes, regardless of a woman's age.
Some studies have found FFDM to be more accurate in finding cancers in women younger than 50. Also, it has been found that women undergoing digital mammography do not have to return for additional studies as often as with standard mammography because the digital images have fewer questionable spots needing more investigation.
However, not all hospitals and mammography facilities have digital equipment available.
ultrasonography - uses high-frequency sound waves, not heard by humans. The sound waves enter the breast and bounce back. The pattern of their echoes produces a picture called a sonogram, which is displayed on a screen. This exam is often used along with mammography.
scintimammography or breast scan - type of nuclear radiology procedure used to assess the breasts when other examinations have been inconclusive. A tiny amount of a radioactive substance is used during the procedure to assist in the examination of the breasts.
In early 2007, the American Cancer Society (ACS) recommended new guidelines which include screening MRI with mammography for certain high-risk women. According to the ACS, contrast-enhanced MRI of the breasts has been shown to have a high sensitivity for detecting breast cancer in women both with or without symptoms.
Based on these exams, your physician may decide that no further tests are needed and no treatment is necessary. In such cases, your physician may want to check you regularly to watch for any changes.
Often, however, the physician must remove fluid or tissue from the breast to be sent to the lab to look for cancer cells. The procedure, called biopsy, may be performed using a needle to acquire a tissue sample or a surgical method.
Always consult your physician for more information.