Radiology, Vol 200, 357-360, Copyright © 1996
by Radiological Society of North America
Positive predictive value of breast biopsy performed as a result of
mammography: there is no abrupt change at age 50 years
DB Kopans, RH Moore, KA McCarthy, DA Hall, CA Hulka, GJ Whitman, PJ
Slanetz and EF Halpern
Department of Radiology, Massachusetts General
Hospital, Harvard Medical School, Boston 02114, USA.
PURPOSE: To determine if the positive predictive value
(PPV) of a biopsy initiated because of an abnormal mammogram changes
abruptly at age 50 years. MATERIALS AND METHODS: The PPV and its
variation with age was analyzed for 4,778 women who underwent biopsy
for a clinically occult abnormality detected at mammography. The
relationship of the results to the patient's age was analyzed with
age represented as a continuous and two-categorized (< 50, >
50) measure. The latter measure represented an abrupt change, which
distinguished those aged 49 years and younger from those aged 50
years and over. With this measure, the patients in each of the two
age groups were statistically indistinguishable. RESULTS: The results
were consistent with a steady increase in PPV and the yield of cancers
with age, and there was no abrupt change at age 50 years. The modeled
PPV for all cancers for these 4,778 patients was approximately 12% for
women aged 40 years and increased to 46% by age 79 years. CONCLUSION: The
PPV did not change abruptly at any age for women aged 40-79 years but increased
steadily, which reflects the prior probability of breast cancer at
each age. Inappropriate grouping of data can lead to misinterpretation of
results. Screening guidelines should not be predicated on the false assumption
that this variable changes at age 50 years.
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