Cancer screening: the importance of outcome measures

Nonbreast cancer incidence, treatment received and outcomes: Are there differences in breast screening attendees versus nonattendees?

While reductions in breast cancer mortality have been evident since the introduction of population-based breast screening in women aged 50-74 years, participation in cancer screening programs can be influenced by several factors, including health system and those related to the individual. In our study, we compared cancer incidence and mortality for several cancer types other than breast cancer, noncancer mortality and patterns of treatment amongst women who did and did not participate in mammography screening. All women aged 50-65 years enrolled on the Queensland Electoral Roll in 2000 were included. The study population was then linked to records from the population-based breast screening program and private fee-for-service screening options to establish screened and unscreened cohorts. Diagnostic details for selected cancers and cause of death were obtained from the Queensland Oncology Repository. We calculated incidence rate ratios and hazard ratios comparing screened and unscreened cohorts. Among screened compared to unscreened women, we found a lower incidence of cancers of the lung, cervix, head and neck and esophagus and an increase in colorectal cancers. Cancer mortality (excluding breast cancer) was 35% lower among screened compared to unscreened women and they were also about 23% less likely to be diagnosed with distant disease. Screened compared to unscreened women were more likely to receive surgery and less likely to receive no treatment. Our study adds further to the population data examining outcomes among women participating in mammography screening.

Effect of financial incentives on breast, cervical and colorectal cancer screening delivery rates: Results from a systematic literature review

Preventive care, such as screening, is important for reducing the risk of cancer, a leading cause of death worldwide. Indeed, some type of cancers are detected through screening programs, which in most countries run for colorectal, breast, and cervical cancers. In this context, general practitioners play a key role in increasing the participation rate in cancer screening programs. To improve cancer screening delivery rates, performance incentives have increasingly been implemented in primary care by healthcare payers and organizations in different countries. The effects of these tools are still not clear. We conducted a systematic literature review in order to answer the following research question: What is the evidence in the literature for the effects of financial incentives on the delivery rates of breast, cervical and colorectal cancer screening in general practice? We performed a literature search in Web of Science, PubMed, Cochrane Library and Google Scholar, according to the PRISMA guidelines. 18 studies were selected, classified and discussed according to the health preventive services investigated. Most of studies showed partial or no effects of financial incentives on breast and cervical cancer screening delivery rates. Few positive or partial effects were found regarding colorectal cancer screening. Ongoing monitoring of incentive programs is critical to determining the effectiveness of financial incentives and their effects on the improvement of cancer screening delivery rates.

Disutility associated with cancer screening programs: A systematic review

OBJECTIVES

Disutility allows to identify how much population values intervention-related harms contributing to knowledge on the benefits/harms ratio of cancer screening programs. This systematic review evaluates disutility related to cancer screening applying a utility theory framework.

METHODS

Using a predefined protocol, Embase, Medline Ovid, Web of Science, Cochrane, Google scholar and supplementary sources were systematically searched. The framework grouped disutilities associated with breast, cervical, lung, colorectal, and prostate cancer screening programs into the screening, diagnostic work up, and treatment phases. We assessed the quality of included studies according to the relevance to target population, risk of bias, appropriateness of measure and the time frame.

RESULTS

Out of 2840 hits, we included 38 studies, of which 27 measured (and others estimated) disutilities. Around 70% of studies had medium to high-level quality. Measured disutilities and Quality Adjusted Life Years loss were 0-0.03 and 0-0.0013 respectively in screening phases. Both disutilities and Quality Adjusted Life Years loss had similar ranges in diagnostic work up (0-0.26), and treatment (0.09-0.27) phases. We found no measured disutilities available for lung cancer screening and-little evidence for disutilities in treatment phase. Almost 40% of the estimated disutility values were above the range of measured ones.

CONCLUSIONS

Cancer screening programs led to low disutities related to screening phase, and low to moderate disutilities related to diagnostic work up and treatment phases. These disutility values varied by the measurement instrument applied, and were higher in studies with lower quality. The estimated disutility values comparing to the measured ones tended to overestimate the harms.

Considerations in the design of randomized trials to screen for type 2 diabetes

Background Randomized controlled trials (RCTs) are the most robust and valid approach to evaluate screening for diseases. Many in the diabetes research community have advocated sole reliance on RCTs for designing diabetes screening policies. However, the challenges of conducting RCTs of screening for type 2 diabetes may have been underappreciated. Purpose Discuss the key theoretical concepts and practical challenges of designing and conducting RCTs of diabetes screening. Methods Narrative and critical review of the literature pertaining to the theory and practice of designing and conducting RCTs of diabetes screening. Results We present the theoretical basis of a diabetes screening trial, using concepts developed mainly in studies of cancer screening and illustrations from the Cambridge component of the Anglo Danish Dutch Study of Intensive Treatment In peOple with screeN-detected diabetes in primary care (ADDITION-Cambridge), the only extant trial of diabetes screening. We examine design issues, including the appropriate trial question, choice of design, and duration of follow-up, and address aspects of trial implementation, including recruitment, randomization, endpoint determination, sample size requirements, and screening interval. Limitations The limited number of trials of diabetes screening did not permit us to illustrate many of the practical difficulties one encounters when implementing theoretical concepts. Conclusion When diabetes screening trials are planned, we suggest careful consideration to potential areas of practical difficulty, especially the need for particularly large sample sizes and extended follow-up, and the choice of appropriate outcomes and screening intervals.

Quantification of harms in cancer screening trials: literature review

OBJECTIVES

To assess how often harm is quantified in randomised trials of cancer screening.

DESIGN

Two authors independently extracted data on harms from randomised cancer screening trials. Binary outcomes were described as proportions and continuous outcomes with medians and interquartile ranges.

DATA SOURCES

For cancer screening previously assessed in a Cochrane review, we identified trials from their reference lists and updated the search in CENTRAL. For cancer screening not assessed in a Cochrane review, we searched CENTRAL, Medline, and Embase.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Randomised trials that assessed the efficacy of cancer screening for reducing incidence of cancer, cancer specific mortality, and/or all cause mortality.

DATA EXTRACTION

Two reviewers independently assessed articles for eligibility. Two reviewers, who were blinded to the identity of the study's authors, assessed whether absolute numbers or incidence rates of outcomes related to harm were provided separately for the screening and control groups. The outcomes were false positive findings, overdiagnosis, negative psychosocial consequences, somatic complications, invasive follow-up procedures, all cause mortality, and withdrawals because of adverse events.

RESULTS

Out of 4590 articles assessed, 198 (57 trials, 10 screening technologies) matched the inclusion criteria. False positive findings were quantified in two of 57 trials (4%, 95% confidence interval 0% to 12%), overdiagnosis in four (7%, 2% to 18%), negative psychosocial consequences in five (9%, 3% to 20%), somatic complications in 11 (19%, 10% to 32%), use of invasive follow-up procedures in 27 (47%, 34% to 61%), all cause mortality in 34 (60%, 46% to 72%), and withdrawals because of adverse effects in one trial (2%, 0% to 11%). The median percentage of space in the results section that reported harms was 12% (interquartile range 2-19%).

CONCLUSIONS

Cancer screening trials seldom quantify the harms of screening. Of the 57 cancer screening trials examined, the most important harms of screening--overdiagnosis and false positive findings--were quantified in only 7% and 4%, respectively.

Screening for bladder cancer: theoretical and practical issues in considering the treated and untreated natural history of the various forms of the disease

Screening is used to detect disease earlier in its course, allow earlier treatment, and presumably decrease morbidities and potential mortality associated with the later expression of more advanced disease and presumably more complex treatments consequently required. Judicious screening in bladder cancer depends on an understanding of how the different forms of bladder cancer express their biological potential, whether the tools available for screening have sufficient sensitivity and specificity to have accurate predictive value in accurately diagnosing and assessing each cancer diathesis earlier in its course, and how this may influence the morbidities and mortality associated with each. The principles of screening, potential biases that can affect their accuracy and the interpretation of outcomes, tools currently available for screening, their efficacies and pitfalls, and lessons learned from studies of the role of screening in prostate cancer will be reviewed to offer an understanding of the potential role that screening may play in the different forms of bladder cancer in the context of their preclinical and treated natural history.

Early impact and performance characteristics of an established anal dysplasia screening program: program evaluation considerations

BACKGROUND

Screening for invasive anal cancer and its precursors is being increasingly advocated as a response to increasing incidence among HIV-infected persons. We implemented a comprehensive screening program in 2001 and report our early experience to inform monitoring and evaluation of such programs. Our research aims were: (1) to estimate incidence of and mortality from invasive anal cancer (IAC) before (1995-2000) and after (2001-2005) screening program implementation and (2) to examine potential screening program quality indicators.

METHODS

The study cohort included all patients under care for HIV infection at UCSD Owen Clinic between 1995-2005. Person-time incidence rates (IR) and case survival of IAC were estimated for the pre-screening (1995-2000) and post-screening (2001-2005) periods. High resolution anoscopy (HRA) operator accuracy was estimated by kappa agreement between cyto-histologic comparisons. Program quality indicators included: (1) screening coverage; (2) percent technically unsatisfactory cytology smears; (3) time between 1st abnormal cytology and 1st HRA; and (4) time between last clinic visit and last cytology.

RESULTS

28 cases of IAC and 13,411 person-years were observed between 1995-2005. IRs (95% CI) pre-screening and post-screening were 199 and 216 per 100,000 person-years, respectively. There was no routine treatment of high grade squamous intraepithelial lesions (HSIL) during the study period. The percent of patients with IAC requiring chemoradiation decreased from 90.9% to 70.6% (p=0.36). There was a significant improvement in cyto-histologic agreement at HRA with increasing operator experience (r=0.92, p=0.025). Screening coverage was 73% of the target population. Among 14 providers, the percent unsatisfactory cytology smears averaged 27% but varied from 0 - 62%. The median time from 1st abnormal cytology to 1st HRA was 258 days. The median interval between the last cytology and the last clinic visit was 207 days.

CONCLUSION

(1) The overall IR of IAC did not decline in the screening era and was higher than previous estimates for HIV cohorts; (2) stage shift to IAC of more favorable prognosis is a reasonable screening goal; (3) HRA accuracy varied by provider experience; (4) because of delay in access to HRA, digital rectal exam should be combined with cytology screening to detect palpable disease.

Surveillance mammography and the risk of death among elderly breast cancer patients

PURPOSE

To examine the benefits of mammography for elderly breast cancer survivors in community settings.

METHODS

Using the 1991-1999 linked SEER-Medicare data, we examined if mammography reduced the risk of breast-cancer-specific and all-cause mortality among women age 66 or older who were diagnosed with first primary breast cancer (FPBC) at stages 0-III and survived at least 30 months. To analyze the influence of mammography (both within one year and within two years prior to death/censoring) on the risk of breast-cancer-specific mortality, we compared women who died of breast cancer (cases) with women who died of other causes or were censored (controls). For an analysis of all-cause mortality, we compared women who died from any cause (cases) with women who were censored (controls). Propensity scores were used to adjust for tumor-related, treatment-related, and sociodemographic confounders.

RESULTS

Among 1351 breast cancer deaths (cases) and 5,262 controls, women who had a mammogram during a one or two-year time interval were less likely to die from breast cancer than women who did not have any mammograms during this time period in propensity-score-adjusted analysis (within one year odds ratio [OR]: 0.83, 95% confidence interval [CI]: 0.72-0.95; within two years OR: 0.80, 95% CI: 0.70-0.92). Similarly, risk of all-cause mortality was reduced among women who had mammograms during one- or two-year intervals.

CONCLUSIONS

In community settings, mammography use during a one- or two-year time interval was associated with a small-reduced risk of breast-cancer-specific and all-cause mortality among elderly breast cancer survivors.

X-ray screening seems to reduce gastric cancer mortality by half in a community-controlled trial in Costa Rica

X-ray screening of gastric cancer is broadly used in Japan, although no controlled trial has proved its effectiveness. This study evaluates the impact of an X-ray screening demonstrative intervention to reduce gastric cancer mortality in a Costa Rican region. The evaluation follows a quasi-experimental, community-controlled design, with measures before and after. About 7000 individuals participated by invitation in the two-wave screening programme. X-ray screening was followed by videoendoscopy and gastric biopsies. Treatment included resection with or without lymph node dissection. Comparisons with two control groups estimate that gastric cancer mortality was halved in the period from 2 to 7 years after the first screening visit. Validity of X-rays as used in this intervention had 88% sensitivity, 80% specificity, and 3% predictive value for individuals with two screening visits. Incidence in the screened group increased up to four times. Case survival was 85% in the intervention group after 5 years, compared to 12% among the controls before the intervention and 35% among the controls in the same region after the intervention. Although X-ray mass screening seems able to reduce stomach cancer mortality, its high cost may be an obstacle for scaling up this intervention in a non-rich country like Costa Rica.