Invasive cervical cancer incidence and mortality among canadian women aged 15 to 29 and the impact of screening.

OBJECTIVE: The utility of screening young women for cervical cancer is questionable given the likelihood of pre-cancer regression and the potential harm of the intervention. Our objective was to determine the incidence and mortality rates of invasive cervical cancer (ICC) in women aged 15 to 29 years and to assess changes in rates since the uptake of screening. METHODS: The incidence of ICC cases from 1970 to 2007 was obtained from records in the Canadian Cancer Registry and from the National Cancer Incidence Reporting System. Mortality rates in women with ICC for the same time period were obtained from the Canadian Vital Statistics Death Database. Data were classified by age group and year at diagnosis or death, assessed at five-year intervals. The incidence was further analyzed according to histology. RESULTS: ICC among 15- to 19-year-olds is rare and has remained relatively constant from 1970-1974 to 2005-2007. From 1975-1979 to 2005-2007, the incidence in 20- to 24-year-olds declined from 3.2 to 1.2 per 100 000. From 1980-1984 to 2005-2007, the incidence in 25- to 29-year-olds declined from 11.1 to 6.3 per 100 000. Deaths among 15- to 19-year-olds and 20- to 24-year-olds are rare, but in 25- to 29-year-olds mortality declined from 0.9 to 0.5 per 100 000 between 1975-1979 and 2005-2007. Among 20- to 24-year-olds, rates of all cervical cancers and squamous cell carcinomas declined, while adenocarcinomas and unknown types were rare. In 25- to 29-year-olds there was a decline in all cervical cancers and squamous cell cancers and an apparent increase in adenocarcinoma. CONCLUSIONS: ICC in adolescents is rare and does not justify population-based screening. Screening appears to have affected the incidence of ICC in 20- to 24-year olds and incidence and mortality from ICC in 25- to 29-year-olds.

Reduced cervical cancer incidence and mortality in Canada: national data from 1932 to 2006.

BACKGROUND: High levels of participation in cervical screening are reported in Canada from the 1970's as a result of early uptake of the Pap smear and universal Medicare. Despite recommendations to the contrary, the programs have featured early age of initiation of screening and frequent screening intervals. Other countries have achieved successful outcomes without such features. We analyzed national data to better understand mortality and incidence trends, and their relationships to screening. METHODS: The Canadian Cancer Registry, National Cancer Incidence Reporting System, and the Canadian Vital Statistics Database were used to measure mortality and incidence rates. Cases and deaths from invasive cervical cancer were classified by 5 year age groups at diagnosis and death (15 to 19 years through to 80 to 84 years), year of diagnosis (1972 to 2006), and year of death (1932 to 2006). Probabilities of developing and dying from cervical cancer were calculated for age-specific mortality and incidence. The proportion of women reporting a timely Pap test was estimated for 1978 to 2006. RESULTS: Cervical cancer mortality has declined steadily from a peak of 13.5 to 2.2 per 100,000 (83%,) between 1952 and 2006, and 71% between 1972 and 2006. Incidence of invasive cervical cancer has declined by 58% since 1972. These declines have occurred more among older age groups than younger. Invasive cervical cancer incidence and mortality is less in each successive birth cohort of women. Participation rates in screening are high especially in women under age 50. CONCLUSIONS: Despite increasing risk factors for cervical cancer, both incidence and mortality have declined over time, across age groups, and across birth cohorts. Earlier increasing mortality (1932 - 1950) was likely related to improved classification of cancers and the early subsequent reduction (1950 - 1970) to improved treatment. Recent improvements in incidence and mortality are likely due to high rates of screening. For women under age 30 years there are low rates of disease but lesser improvement related to screening.