Incidence, survival and mortality in cervical cancer in Norway, 1956-1990.

Long-term trends in incidence, survival and mortality were examined in women with squamous cell carcinoma and adenocarcinoma of the uterine cervix, diagnosed in Norway in the 35-year period 1956-1990. During the 1970s the number of cervical smears increased substantially in Norway, although no organised screening programme was introduced. Special attention was paid to the time period 1971-1990 to evaluate the effect of the extensive spontaneous screening. In addition, the prognostic importance of clinical stage and age was explored. In the squamous cell carcinoma patients the incidence rate peaked in the time period 1971-1975, since when there has been a decrease. In the adenocarcinoma patients the incidence rate rose through the years 1976-1990. Also, the proportion of adenocarcinomas increased in this time period. The mortality rates in both histological types declined modestly through the years 1966-1990. A more favourable stage distribution was noted among the squamous cell carcinomas (P = 0.00), but not among the adenocarcinomas, when comparing the two diagnostic periods 1971-1975 and 1981-1985. The multivariate analysis (GLIM) revealed that stage was the most important prognostic factor in both histological types (P = 0.00). In the squamous cell carcinoma patients the relative rate increased (P = 0.04) in the last period. There was a tendency towards a poorer prognosis in younger women in this group, but age did not prove to be an important prognostic factor (P = 0.08).