Etiology and prevention of cervical adenocarcinomas.

Adenocarcinomas of the uterine cervix (ACs) constitute a relatively rare histologic form of cervical cancer. However, while rates of the more common squamous cell carcinomas of the cervix (SCC) have shown consistent declines in incidence over time in countries where effective cytological screening programs exist, rates of AC have increased over the same period ( 1 – 3 ) . This has led to an increase in the proportion of cervical cancers attributable to AC in many countries. In the United States, ACs now make up more than 20% of all cervical cancer cases diagnosed each year ( 4 ) . The underlying reasons for the increases observed for AC are not well understood. They are likely due to a complex interplay between temporal changes in exposures that predispose to the development of AC and changes in cervical cancer screening practices ( 1 ) . Changes in screening practices and their likely impact on AC rates are in themselves diffi cult to understand because they include changes that are likely to have countervailing effects on disease rates. For example, increased awareness of AC, improved diagnostic classifi cation of these conditions, and improvements in cervical sampling devices and slide preparation methods might initially result in increased detection of invasive AC. These improvements would also lead to increased detection of AC at an earlier — in situ — state, which would subsequently lead to decreases in overall rates of invasive AC. Unlike the situation with SCC, however, this predicted long-term impact of improved screening on AC rates might be muted by limitations resultant from the diffi culty of detecting AC, which often arise deep in the endocervical canal, in areas that despite the improvements in screening alluded to above are still not easily sampled during routine screening. In this issue of the Journal, Castellsague and colleagues report fi ndings from a multicenter study of AC ( 5 ) . The results have important implications for our understanding of both the causes and possible prevention of AC. Each of these aspects is discussed below.