ReviewProcess of care failures in invasive cervical cancer: Systematic review and meta-analysis
Introduction
Cervical cancer is the most common gynaecologic neoplasm and the second most frequent cancer in women worldwide, with an estimated 493,000 incident cases of cervical cancer occurring annually (Ferlay et al., 2004). Neoplastic development gradually proceeds through a series of well-defined precursor stages initially confined to the cervical epithelium, which if left untreated may eventually progress to invasion (Meijer et al., 2000). Countries that have implemented the use of the Papanicolaou (Pap) test as part of opportunistic or organized cervical cancer screening programs that included quality assurance, large population coverage, and adequate follow-up experienced a reduction in the incidence and mortality for the disease. Moreover, the extent of this reduction appeared to be proportional to the degree of screening coverage (Franco et al., 2002). Therefore, although Pap cytology was never subjected to the rigours of randomized controlled trials, its effectiveness has been proven through decades of surveillance in populations where screening has been successfully adopted. The basic tenet of cervical cancer prevention is to halt neoplastic growth at the precursor stage prior to invasion through appropriate screening and, if required, the application of confirmatory diagnostic tests and treatments. Thus, at least theoretically, invasive cervical cancer (ICC) is a preventable disease (Miller et al., 2000).
Although great strides have been made in reducing the public health burden due to ICC, its continued occurrence in populations with access to screening has prompted many researchers to investigate the reasons why ICC cases could not be identified at the pre-malignant stage. Typically, these studies enumerated all ICC cases in individual hospitals or regions within a given period of time and performed audits with the purpose of identifying deficient screening histories as the primary reason for why such cases were only identified at the invasive stage. A few studies, however, assessed the occurrence of false-negative screening results and determined the timeliness or existence of follow-up care received for any abnormal cytologic smears or cervical pre-invasive lesions found. The general goal of all studies was essentially to identify failures in the process of care aimed at preventing ICC development.
The objectives of the present study were to review and to summarize the findings of these studies. Meta-analyses were performed to determine overall summary statistics for the types of failures and meta-regression was used to determine the study-level variables that may have influenced these estimates.
Section snippets
Identification of studies
We identified studies through an extensive search of MEDLINE (1950 to the 2nd week of January 2007) based on an exhaustive combination of title and abstract keywords that encompassed the contexts of disease identification via screening, process of care, and evaluation, specifically for cervical cancer. Reference lists of identified articles were also searched for relevant studies. Studies were either case–control or case-only designs that enumerated all cases of ICC that occurred within a given
Characteristics of included studies and study subjects
Overall, 305 articles were identified, of which 42 met our inclusion criteria (Table 1). Subject inclusion criteria, which varied amongst studies, included cancer specific variables, such as tumour histologic type and degree of invasion and subject-related characteristics, such as age at diagnosis, ethnicity/race, Pap screening history, treatment received for ICC, and receipt of invitation to attend for screening.
Among the included studies that provided some demographic information about their
Discussion
A deficient screening history was the most common process failure along the cancer care continuum attributable to the development of ICC, with an overall 54% of women with inadequate screening intervals and 42% of women specifically never screened. The meta-regression revealed that a greater proportion of ICC patients had been screened at least once over their lifetimes in recent studies than in earlier ones. The growing body of evidence surrounding the effectiveness of the Pap smear at
Acknowledgments
This study was supported by grants IHS-61108 and MOP-64454 from the Canadian Institutes of Health Research to ELF. ARS was a recipient of a graduate scholarship from The Cancer Research Society Division of Epidemiology at McGill University.
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