When a screening programme is established, it is important that the diagnostic facilities are adequate—this usually requires additional start-up funding. It is also essential that the diagnosis is of the highest quality to avoid patient dissatisfaction and the litigation that can result from missed disease or misdiagnosed benign pathology. Similarly, treatment of early disease must be associated with minimal morbidity and mortality.
It must also be remembered that screening does cause psychological morbidity, and along with any physical morbidity caused by investigation and treatment, this represents part of the cost of screening. The benefits gained must outweigh such morbidity, and society must make a decision whether or not the health gain justifies the financial cost.
Randomized trials have been done in breast and colorectal cancer, and in both instances screening has been shown to reduce mortality. In the former condition, the screening test studied was the mammo-gram, and efficacy of screening proved highly dependent not only on the quality of the X-rays but also on the quality of the reporting. In colorectal cancer, the test investigated was the faecal occult blood test, followed by colonoscopy when positive. Here, it is the secondary investigation (i.e. the colonoscopy) where quality control is of the utmost importance.
Breast screening is currently available for all women aged 50-65 years in the UK, but provision of colorectal cancer screening is still under discussion. Cervical cancer screening using cervical cytology is established but has never been subjected to a randomized trial.
Was this article helpful?