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- Gustafsson, Leif, et al.
(author)
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International incidence rates of invasive cervical cancer after introduction of cytological screening
- 1997
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In: Cancer Causes and Control. - 0957-5243 .- 1573-7225. ; 8:5, s. 755-763
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Journal article (peer-reviewed)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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| 2. |
- Linet, Martha S., et al.
(author)
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Maternal and perinatal risk factors for childhood brain tumors (Sweden)
- 1996
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In: Cancer Causes and Control. - 0957-5243 .- 1573-7225. ; 7:4, s. 437-448
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Journal article (peer-reviewed)abstract
- Childhood brain tumors (CBT) include a diversity of rare neoplasms of largely unknown etiology. To assess possible maternal and perinatal risk factors for CBT according to subtype, we carried out a nested (within Swedish birth-cohorts, 1973-89) case-control study, utilizing data from the nationwide Birth Registry. We ascertained incident brain tumor cases through linkage of the nationwide Birth and Cancer Registries and randomly selected five living controls from the former, matching each case on gender and birthdate. There were 570 CBT cases, including 205 low grade astrocytomas, 58 high grade astrocytomas, 93 medulloblastomas, 54 ependymomas, and 160 'others.' Risks for all brain tumors combined were elevated in relation to: (i) three maternal exposures-oral contraceptives prior to conception (odds ratios [OR] = 1.6, 95 percent confidence interval [CI] = 1.0-2.8), use of narcotics (OR = 1.3, CI = 1.0-1.6), or penthrane (OR = 1.5, CI = 1.1-2.0) during delivery); (ii) characteristics of neonatal distress (a combined variable including low one-minute Apgar score, asphyxia [OR = 1.5, CI = 1.1-2.0]) or treatments for neonatal distress (use of supplemental oxygen, ventilated on mask, use of incubator, scalp vein infusion, feeding with a jejunal tube [OR = 1.6, CI = 0.9-2.6]); and (iii) neonatal infections (OR = 2.4, CI = 1.5-4.0). Higher subtype-specific risks, observed for a few risk factors, did not differ significantly from the risk estimates for all subtypes combined for the corresponding risk factors. Childhood brain tumors were not associated significantly with other maternal reproductive, lifestyle, or disease factors; perinatal pain, anesthetic medications, birth-related complications; or with birthweight, birth defects, or early neonatal diseases. These findings suggest several new leads, but only weak evidence of brain tumor subtype-specific differences.
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