Reassessing risk models for atypical hyperplasia: age may not matter.

Purpose: The aim of this study was to investigate the influence of age at diagnosis of atypical hyperplasia ("atypia", ductal [ADH], lobular [ALH], or severe ADH) on the risk of developing subsequent invasive breast cancer or ductal carcinoma in situ (DCIS).
Methods: Using standard survival analysis methods, we retrospectively analyzed 1353 women not treated with chemoprevention among a cohort of 2370 women diagnosed with atypical hyperplasia to determine the risk relationship between age at diagnosis and subsequent breast cancer.
Results: For all atypia diagnoses combined, our cohort showed a 5-, 10-, and 15-year risk of invasive breast cancer or DCIS of 0.56, 1.25, and 1.30, respectively, with no significant difference in the (65,75] year age group. For women aged (35,75] years, we observed no significant difference in the 15-year risk of invasive breast cancer or DCIS after atypical hyperplasia, although the baseline risk for a 40-year-old woman is approximately 1/8 the risk of a 70-year-old woman. The risks associated with invasive breast cancer or DCIS for women in our cohort diagnosed with ADH, severe ADH, or ALH, regardless of age, were 7.6% (95% CI 5.9-9.3%) at 5 years, 25.1% (20.7-29.2%) at 10 years, and 40.1% (32.8-46.6%) at 15 years.
Conclusion: In contrast to current risk prediction models (e.g., Gail, Tyrer-Cuzick) which assume that the risk of developing breast cancer increases in relation to age at diagnosis of atypia, we found the 15-year cancer risk in our cohort was not significantly different for women between the ages of 35 (excluded) and 75. This implies that the "hits" received by the breast tissue along the "high-risk pathway" to cancer might possibly supersede other factors such as age.