The rising incidence of adenocarcinoma relative to squamous cell carcinoma of the uterine cervix in the United States - A 24-year population-based study

Objective. The aim of this study was to compare the age-adjusted incidence and survival for invasive adenocarcinoma and squamous cell carcinoma of the uterine cervix using population-based data. Methods. The SEER database was used to identify all cases of cervical cancer registered between 1973 and 1996. Stage was defined as localized, regional, or distant. Age-adjusted incidence rates were analyzed statistically using the Jonchkeere-Terpstra exact test for trends. Relative and observed survival rates, respectively, were compared using z tests and log-rank tests. Results. The age-adjusted incidence rates per 100,000 for all invasive cervical cancers decreased by 36.9% over 24 years [12.35 (1973-1977) vs 7.79 (1993-1996)]. Similarly, the age-adjusted incidence rates for squamous cell carcinoma declined by 41.9% [9.45 (1973-1977) vs 5.49 (1993-1996)]. In contrast, the age-adjusted incidence rates for adenocarcinoma increased by 29.1% [1.34 (1973-1977) vs 1.73 (1993-1996)]. The proportion of adenocarcinoma increased 107.4% relative to all cervical cancer, 95.2% relative to squamous cell carcinoma, and 49.3% relative to the population of women at risk [10.8% vs 22.4% (P < 0.001), 12.4% vs 24.0% (P < 0.001), and 1.40 vs 2.09 per 100,000 women (P < 0.001), respectively]. Observed survival rates for adenocarcinoma vs squamous cell carcinoma were poorer for regional (P = 0.04), but not localized or distant disease. Conclusions. Over the past 24 years, the incidence of all cervical cancer and squamous cell carcinoma has continued to decline. However, the proportion of adenocarcinoma relative to squamous cell carcinoma and to all cervical cancers has doubled, and the rate of adenocarcinoma per population at risk has also increased. These results suggest that current screening practices in the United States are insufficient to detect a significant proportion of adenocarcinoma precursor lesions. (C) 2000 Academic Press.