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- Gustafsson, Leif, et al.
(författare)
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International incidence rates of invasive cervical cancer after introduction of cytological screening
- 1997
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Ingår i: Cancer Causes and Control. - 0957-5243 .- 1573-7225. ; 8:5, s. 755-763
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Tidskriftsartikel (refereegranskat)abstract
- Because Pap-smear screening can detect pre-invasive cervical cancer, such screening can markedly reduce the occurrence of invasive cancer. However, its impact in different populations is uncertain. This study compares the changes in cervical cancer incidence at different ages after the introduction of screening in different populations, and addresses the impact of organized and opportunistic smear taking. We identified 17 cancer registries large enough and existing long enough to analyze screening effects. For each registry, we calculated the relative reduction in age-specific incidence rates and in incidence rates age-standardized to the world population after the introduction of cytologic screening. In 11 of the 17 populations, age-standardized incidence rates declined markedly from 27 percent in Norway and to 77 percent in Finland. Age-specific declines were confined to women aged 30 to 70 years old with a nadir around ages 40 to 55. In six other populations, age-standardized incidence rates declined less than 25 percent, an amount too small to provide unambiguous evidence of a screening effect. In several populations, cytologic screening had a more pronounced effect than is generally recognized. Because age-specific declines in cervical cancer incidence rates were strikingly similar in populations with widely different screening practices, organized screening may not be markedly superior to opportunistic screening. The reduction in reported cancer incidence because of screening is smaller in younger and older women.
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- Gustafsson, Leif, et al.
(författare)
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International incidence rates of invasive cervical cancer before cytological screening
- 1997
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Ingår i: International Journal of Cancer. - 0020-7136 .- 1097-0215. ; 71:2, s. 159-165
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Tidskriftsartikel (refereegranskat)abstract
- Huge differences in incidence rates of invasive cervical cancer occur among populations. These differences reflect the influences of both etiological environmental factors and removal of precursor lesions detected upon screening. The purposes of this article are (i) to describe similarities and differences in the shapes and magnitudes of age-specific incidence rates of invasive cervical cancer before screening had an effect, (ii) to provide baseline data for further global study of screening effects, and (iii) to provide baseline incidence data for the design of optimal screening programs. To eliminate the impact of screening effects, we have selected age-specific incidence rates from times when and from populations in which screening was insignificant. The selected rates were suitably scaled and compared regarding age at onset of increase in incidence, age at peak incidence, and rate of subsequent decline. Despite a 16-fold difference in incidence rates, all curves had the same basic structure, with an increase to a peak followed by a decline or a plateau. Although all populations but one had an onset around age 25, 7 European countries showed an earlier peak age (mean = 46 vs. 59) and a more rapid decline after the peak than most other populations. The common basic shape of the age-specific incidence curve, overall, suggests a relatively similar development of invasive cervical cancer in different populations. These results illustrate the underlying similarities in the markedly different age-specific incidence rates of invasive cervical cancer. They also provide a basis for studying screening effects and for optimizing screening programs in specific geographic areas.
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