Abstract

     Cancer screening is a source of much debate. At the interface between public health, specialist care, economics and public health policy, it creates tensions between professional groups, politicians, the media and the public. A screening test may be cheap but applying it to a population (with rigorous quality control and effective downstream processing of patients with abnormal results) creates a huge workload and cost. Screening can also have profound psychological effects. People with false-positive results require investigation yet are usually eventually found not to have cancer. Unless screening can be shown to reduce mortality from specific cancers, the resources used are better spent on improving care, and this has led to disparities in screening recommendations between countries. Advances in understanding the genetic basis of cancer are likely to provide new approaches to cancer risk assessment and new challenges for developing screening strategies, by risk-banding populations based on polymorphisms in low-penetrance cancer risk genes. The American Cancer Society guidelines for cancer screening, reviewed annually, represent a global gold standard that is difficult to emulate in most healthcare economies because of cost and under-capacity for downstream processing of abnormal findings. Tailoring cancer screening recommendations to a country’s health economy is an essential public health intervention.

Introduction

     Cancer screening seems so logical to all healthcare workers and patients alike. We all know that early cancer is curable in the majority of cases and later stage disease is not. So, picking up cancer before a patient has symptoms would seem ideal. The problem is that none of the tests available are perfect. And the resources spent on screening programmes may well be better spent on speeding up appropriate referral of symptomatic patients. Here, we will consider the advantages of screening along with the downside for the common cancers.

     The long-awaited publication of the independent review on national cancer screening programmes in England makes grim reading.1 Two disastrous information technology failures e one in breast cancer and the other in cervical cancer e were revealed in 2018. Thousands of patients were simply deleted from the computer database by accident. New technologies such as the faecal immunochemical test (FIT) and once-only colonoscopy programmes are still not fully rolled out even though plans were unveiled 8 years ago. And although much talked about, artificial intelligence currently plays little part in data interpretation except in research settings. Crucially, the consumer uptake of each of the three major programmes e breast, colon and cervix e is in decline, especially in deprived areas. The impact of coronavirus disease (COVID-19) has been severe and services are only just beginning to clear the huge backlog generated.2

The future

     New technology such as the microanalysis of circulating DNA e so-called liquid biopsy e could radically change the situation. Future changes in cancer screening will lead to profound ethical, educational, commercial and medical challenges. Completion of the Human Genome Project, the ability to handle large volumes of sequence data, and rapid and inexpensive assays for mutations using gene-chip technology will transform the assessment of cancer risk. Commercial pressures have caused the major pharmaceutical companies to invest heavily in genomics, and their interest will lead to the discovery of new drugs and more specific tailoring of therapies to individual patients. It is likely that groups of individuals with no family history of cancer will be identified as being at significantly increased risk of developing cancer. Devising optimal screening schedules for such groups will be a major challenge.

     The biggest problem of all is motivating the customers. The compliance rate varies enormously across the world, driven by education, socioeconomic factors and deprivation.5 The educated worried well are likely to go for every free test offered by the health system. The socially excluded residents of the neighbouring poorer districts on the wrong side of the tracks will not visit the doctor until they have advanced stage 4 cancer. And yet private clinics offer top of the range health screening for >£۳۰۰۰ of scans and tests to the gullible wealthy with no evidence of benefit. To save lives most effectively, we must target the poor.