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Wolfe's criteria were assigned to mammograms of 202 women without breast cancer. Parity decreased the frequency of P2 patterns but not DY. P1 and N1 patterns apparently increased at the expense of P2 patterns. For every birth, the probability that a P2 pattern changed to P1 or N1 was roughly 7 or 8%. This effect was not limited to the first pregnancy, but also held for additional pregnancies. Low body weight was associated with dysplasia and prominent duct patterns. Reported declines of radiographic density with increasing age and/or menopause were confirmed. Ethnic group was unrelated to parenchymal pattern.

Anti-M alone appears sufficient to detect autoimmune thyroid disease at about one half the cost of routinely performing both anti-M and anti-Tg studies. The widespread practice of performing both tests increases the cost without an offsetting diagnostic gain.

Wolfe defined four different classes of breast parenchymal patterns and claimed that they were associated with different risks for the subsequent development of breast cancer. Egan and Mosteller suggested that these patterns did not constitute a true risk factor, rather the effect was caused by the greater difficulty of detecting breast cancers in the dense (P2, DY) patterns compared with the fatty (N1, P1) patterns. Similarly, Mendell believed that a bias was introduced into Wolfe's work by requiring a negative mammogram before a patient entered the study. This study of 221 prevalent and 706 incident cancers followed for up to 10 years indicates that a masking effect does exist, but that it operates in addition to a difference in risk of breast cancer within the four Wolfe classes. Wolfe's hypothesis is found to be valid.