Atypical Breast Lesions: How High Is the
Cancer Risk?
By Caroline Helwick
March 1, 2012, Volume 3, Issue 4
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Women with atypical breast lesions have approximately a 5% to 11% risk of developing
breast cancer within 5 years, depending on histology, and this risk can be reduced with
chemoprevention, according to a presentation at the 2011 San Antonio Breast Cancer
Symposium.1
Investigators tracked the outcomes of 2,942 women with atypical breast
lesions treated at Boston area hospitals. The study was led by Suzanne B. Coopey, MD, a
surgical oncologist at Massachusetts General Hospital, Boston, and was presented by senior
investigator Kevin S. Hughes, MD, also a surgical oncologist at Massachusetts General.
“While all types of atypical lesions are known to increase the risk of breast cancer, it is not
clear from the medical literature just how much they increase risk, because there are
conflicting data,” Dr. Hughes noted. “Also, the effect of chemoprevention in the clinical setting
needs to be clarified.”
Large Population Analyzed
Dr. Coopey and colleagues reviewed 76,333 pathology reports for 42,950 individuals and
identified 2,942 women (mean age 51) diagnosed with atypical breast lesions between 1987
and 2010. This included 1,199 (40.8%) with atypical ductal hyperplasia, 828 (28.1%) with
atypical lobular hyperplasia, 570 (19.4%) with lobular carcinoma in situ, and 345 (11.7%) with
borderline ductal carcinoma in situ/severe atypical ductal hyperplasia. The effect of
chemoprevention was analyzed from 1999 forward.
After an overall follow-up of 67 months, breast cancer was diagnosed in 7.1% of women with
atypical ductal hyperplasia, 10.9% with atypical lobular hyperplasia, 11.1% with lobular
carcinoma in situ, and 8.4% with borderline ductal carcinoma in situ/severe atypical ductal
hyperplasia. Median time to breast cancer diagnosis was 48 months, 50 months, 47 months,
and 60 months, respectively. There were significantly more ipsilateral cancers for all atypical
types combined (P < .005), and bilateral cancers were rare, Dr. Hughes reported.
“The different diagnoses did not carry different levels of cancer risk,” he observed. “This is not
what we expected when we started the study.” The breast cancer risks by type of atypia are
shown in Table 1.
Invasive cancers were significantly more common than noninvasive cancers among patients
with lobular carcinoma in situ (71.1%) and atypical lobular hyperplasia (68.9%) (P < .001) but
were not more frequent for the other types of lesions (47.4% in atypical ductal hyperplasia
and 57.1% in patients with borderline lesions), he said.
Outcomes with Chemoprevention
Among the 2,460 patients diagnosed since 1999, chemoprevention with tamoxifen, raloxifene
(Evista), and/or exemestane (for any duration) was received by 466 (18.9%), whereas 1,472
(59.8%) received no treatment. (Data were not available for 21.2% of patients.)
“Chemoprevention had a clear effect, significantly decreasing the risk of cancer occurrence
for all atypia types,” Dr. Hughes reported. “But only 20% of patients took these medications,
which certainly leaves room for improvement.”
At 5 years, cancer occurred in only 4.1% receiving some type of chemopreventive agent, vs
8.3% of patients left untreated. At 10 years, the difference widened, with cancer diagnosed in
7.5% vs 21.3% (P < .05).
By atypia type, for chemoprevention vs no treatment, the 10-year cancer risks were 8.5% vs
19.9% for atypical ductal hyperplasia, 8.5% vs 18.7% for atypical lobular hyperplasia, 2.1% vs
14.7% for borderline lesions, and 10.3% vs 32.4% for lobular carcinoma in situ. All were
statistically significant (P < .05), he said.
Interest Sparked Discussion
Several questions from attendees followed the presentation, and discussion was lively. Dr.
Hughes said his group hopes to mine the data to determine risk according to age, benefit of
chemoprevention by duration of treatment, risk according to amount or magnitude of atypia,
and other factors that might further delineate cancer risk and the value of chemoprevention.
Elaborating on the high incidence of noninvasive ductal carcinoma in situ (approximately
40%) diagnosed over time, Dr. Hughes noted that patients were closely followed with yearly
mammograms. “The high rate of screening might explain this high rate,” he said.
When asked which patients should receive chemoprevention, he said, “I tend to use
chemoprevention for any patient with atypia, though we need to decide if we can exclude
patients age 70 and older.” He added that more needs to be learned regarding the safety of
chemopreventive agents in patients with certain risk factors. ■
Disclosure: Drs. Hughes and Coopey reported no potential conflicts of interest.
Reference
1. Coopey SB, Mazzola E, Buckley JM, et al: Clarifying the risk of breast cancer in women
with atypical breast lesions. 2011 San Antonio Breast Cancer Symposium. Abstract S4-4.
Presented December 7, 2011.