Mammograms are extremely vital for early detection of breast cancer, yet for younger women under the age of 40 years, their performance is questionable.
Yankaskas and colleagues investigated the performance of first mammography examinations of women under the age of 40 years.10 For women between the ages of 35 and 39, they found that the sensitivity of the exams was 76.1% and the specificity was 87.5%. The breast cancer rate among women between 35 and 39 years is 0.000293 (about 29.3 per 100,000 women).11 Based on these data, if a mammography exam for a woman between the ages of 35 and 39 detects breast cancer, use Bayes’ rule to find the probability that she does have breast cancer. What does your result indicate about the performance of mammograms for women between the ages of 35 and 39 years?