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More Breast Screening Benefits
(HealthScoutNews) -- Approximately
one in every 1,300 mammograms will result in a diagnosis of ductal
carcinoma in situ (DCIS), a type of non-invasive tumor that makes
up roughly 20 percent of breast cancers detected by screening,
says new research.
A study in today's issue of the Journal
of the National Cancer Institute found that as the use of
screening mammography has increased, the detection of DCIS --
which usually cannot be felt by a clinical exam -- has also risen.
But because the lesions are removed
when detected, doctors are uncertain what percentage of such lesions,
if untreated, would progress to invasive breast cancer.
Studies have shown that only a fraction
of DCIS treated by lumpectomy (removal of the lump) alone later
progress to invasive cancer. Thus, there is a concern that diagnosis
and treatment of many DCIS cases may not be beneficial.
Non-invasive tumors are those that
have not spread into the breast tissue and are contained within
the cells lining the milk ducts.
The researchers, Virginia L. Ernster,
of the University of California, San Francisco, and Rachel Ballard-Barbash,
of the National Cancer Institute, found that the percentage of
screen-detected breast cancers that were DCIS decreased with age.
For example, in women between the
ages of 40 and 49, 28.2 percent of screen-detected breast cancers
were DCIS; in women 70 to 84, 16 percent of screen-detected breast
cancers were DCIS.
However, the rate of DCIS diagnoses
per 1,000 mammograms increased with age, from 0.56 per 1,000 for
women ages 40 to 49 to 1.07 per 1,000 for women ages 70 to 84.
Further analysis revealed that mammograms were more sensitive
at detecting DCIS than they were for detecting invasive breast
cancer or tumors that have spread into the breast tissue.
The authors point out that the likelihood
of benefit from treatment of DCIS is probably greater for women
with larger, higher-grade lesions than for those with very small,
low-grade lesions.
More Information
An overview on
DCIS can be found here.
Reference
Source 101
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