Why does cervical cancer occur in a state-of-the-art screening program?
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ABSTRACT: BACKGROUND:The goal of cervical screening is to detect and treat precancers before some become cancer. We wanted to understand why, despite state-of-the-art methods, cervical cancers occured in relationship to programmatic performance at Kaiser Permanente Northern California (KPNC), where >1,000,000 women aged ?30years have undergone cervical cancer screening by triennial HPV and cytology cotesting since 2003. METHODS:We reviewed clinical histories preceding cervical cancer diagnoses to assign "causes" of cancer. We calculated surrogate measures of programmatic effectiveness (precancers/(precancers and cancers)) and diagnostic yield (precancers and cancers per 1000 cotests), overall and by age at cotest (30-39, 40-49, and ?50years). RESULTS:Cancer was rare and found mainly in a localized (treatable) stage. Of 623 cervical cancers with at least one preceding or concurrent cotest, 360 (57.8%) were judged to be prevalent (diagnosed at a localized stage within one year or regional/distant stage within two years of the first cotest). Non-compliance with recommended screening and management preceded 9.0% of all cancers. False-negative cotests/sampling errors (HPV and cytology negative), false-negative histologic diagnoses, and treatment failures preceded 11.2%, 9.0%, and 4.3%, respectively, of all cancers. There was significant heterogeneity in the causes of cancer by histologic category (p<0.001 for all; p=0.002 excluding prevalent cases). Programmatic effectiveness (95.3%) and diagnostic yield were greater for squamous cell versus adenocarcinoma histology (p<0.0001) and both decreased with older ages (ptrend<0.0001). CONCLUSIONS:A state-of-the-art intensive screening program results in very few cervical cancers, most of which are detected early by screening. Screening may become less efficient at older ages.
SUBMITTER: Castle PE
PROVIDER: S-EPMC5743197 | biostudies-literature | 2017 Sep
REPOSITORIES: biostudies-literature
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