Most cases of simple hyperplasia without atypia undergo spontaneous regression. Only about 1% progress to adenocarcinoma. At the other end of the spectrum, almost 30% of complex hyperplasia with atypia cases progress to adenocarcinoma.(Source: Malpica, Deavers, and Euscher. Biopsy interpretation of the uterine cervix and corpus. Lippincott, William & Wilkins, p. 167-168, 2010).