TableĀ 1

Similarities and differences between aspects of organised and opportunistic screening (reproduced with permission from Miles et al 16)

Aspect of screeningOrganised screeningOpportunistic screening
Screening method for a particular type of cancer (eg, FOBT vs FS)Fixed: chosen by government/health departmentVariable: chosen by individual and individual healthcare provider
AimReduce cancer incidence/mortality at the population levelReduce cancer incidence/mortality at the individual level
Sensitivity of testThe most sensitive test may not be chosen for a nationwide programme. Sensitivity targets for practitioners and programmes are established and monitored to improve test performanceThe most sensitive test is usually chosen. Sensitivity at the practitioner and programme levels is not generally monitored
Specificity of testHigh specificity is important for reducing avoidable costs due to unnecessary workup of false-positive results associated adverse effectsHigh specificity is less important at the individual level
Screening intervalFixed: chosen to maximize population benefit at reasonable costVariable: chosen to maximise an individual's protection against cancer morbidity/mortality; usually more frequent than in organised programmes
Available financial resourcesLimited at the population level in relation to policies of health spending, taking into account all aspects of healthcareLimited at the level of the individual, and limited to health plan-level decisions; depends primarily on the finances and insurance status of the individual
Health technology assessmentMust be confirmed to yield more benefit than harmEfficacy does not necessarily have to be demonstrated
Quality assuranceSet targets have to be met and are monitored. Targets are continually reviewed to ensure that the screening delivered is of the highest quality possibleTargets may be set and may or may not be monitored
Target uptake ratesSpecified and monitored; lower rates result in organised efforts for improvementMay or may not be specified (ie, by health plans or health agencies) or monitored; few opportunities for systematic applications for population-based improvement
Persons invitedFixed: all persons within a specified age rangeVariable: persons in contact with healthcare professionals who recommend screening; persons with particular jobs in which healthcare coverage may include reimbursement for screening; anyone exposed to direct-to-consumer marketing
Invitation strategyActive: everyone in the eligible population is invitedPassive: no consistent strategy
Aim for equality of accessEquality of access is built into the organisation of the programmeEquality of access is desired, but resources allocation limits the potential of outreach efforts
Relation between persons invited and cancer riskThose invited are not necessarily the persons at highest risk but represent the age group most likely to receive greatest benefits from screeningThose invited are not necessarily the persons at highest risk; this feature may lead to overscreening of low-risk persons and underscreening of high-risk persons
BenefitsMaximised for the population within available resourcesMaximized for the individual
HarmsMinimised for the population within available resourcesNot necessarily minimised
  • FOBT, faecal occult blood test; FS, flexible sigmoidoscopy.