The rising incidence of adenocarcinoma relative to squamous cell carcinomaof 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 cance r registered between 1973 and 1996. Stage was defined as localized, regiona l, or distant. Age-adjusted incidence rates were analyzed statistically usi ng the Jonchkeere-Terpstra exact test for trends. Relative and observed sur vival rates, respectively, were compared using z tests and log-rank tests. Results. The age-adjusted incidence rates per 100,000 for all invasive cerv ical cancers decreased by 36.9% over 24 years [12.35 (1973-1977) vs 7.79 (1 993-1996)]. Similarly, the age-adjusted incidence rates for squamous cell c arcinoma declined by 41.9% [9.45 (1973-1977) vs 5.49 (1993-1996)]. In contr ast, the age-adjusted incidence rates for adenocarcinoma increased by 29.1% [1.34 (1973-1977) vs 1.73 (1993-1996)]. The proportion of adenocarcinoma i ncreased 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 1 00,000 women (P < 0.001), respectively]. Observed survival rates for adenoc arcinoma vs squamous cell carcinoma were poorer for regional (P = 0.04), bu t not localized or distant disease. Conclusions. Over the past 24 years, the incidence of all cervical cancer a nd squamous cell carcinoma has continued to decline. However, the proportio n 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 o f adenocarcinoma precursor lesions. (C) 2000 Academic Press.