Screening Programmes

Colorectal cancer (CRC) screening using faecal tests reduces disease-specific mortality. To investigate mortality and its association with sex, rates in women and men, and in different age ranges, were examined, before and after screening began in Scotland. CRC mortality fell during 1990–2020, but the decline differed markedly between sexes, indicating a larger beneficial effect of screening on CRC mortality in men compared to women: use of different thresholds for the sexes might lead to equality.

In symptomatic, suspect lower GI cancer patients qFIT is a useful adjunct for prioritising patients and can be used to determine the urgency of colorectal investigations.

Adenomas may be rarely the cause of a positive FIT result. An alternative explanation as to why these are detected using FIT is required. In addition, a negative colonoscopy for a positive FIT result does not rule out the finding of significant neoplastic pathology in the next round.

We observed age and sex disparities in polyp types and prevalence in this outpatient colonoscopy population.  SSLs were most prevalent in females aged < 50 years, suggesting a potential increased susceptibility of young females to SSLs and CRC. Our findings may have implications for the design of CRC screening programs.

In a population-based CRC screening programme, smart use of number of FITs and positivity threshold can increase population invited and CRC detection without increasing the number of colonoscopies and pathological examinations needed.

Both these factors are important considerations for laboratories when considering setting up a bowel cancer screening programme, especially if transitioning from gFOBT to FIT. Our data also support previous evidence of males having a higher f-Hb than females and demonstrate that after adjusting for sex, age and screening hub, neither index of multiple deprivation nor screening episode significantly affected f-Hb.

A paper from the Scottish Bowel Screening Programme on the transition from guaiac based Faecal Occult Blood tests (gFOBT) to faecal immunochemical testing (FIT) in the Screening population. The authors conclude; “Transition to FIT from FOBT produced higher uptake and positivity with lower PPV for CRC and higher PPV for adenoma”.

An entry by Prof. Fraser on the Scottish Cancer Prevention Network (SCPN) blog regarding patient sampling and the possible implications of this on both screening and symptomatic assessment.

Markedly improved participation rates were achieved in a mature gFOBt-based national screening programme and disparities between men and women were reduced. High positivity rates, particularly in men and previous non-respondents, challenge the available colonoscopy resource, but improvements in neoplasia detection are still achievable within this limited resource.

Randomised controlled trial (ISRCTN20086618) within a population-based colorectal cancer (CRC) screening programme. Subjects eligible for invitation in the Umbria Region (Italy) programme were randomised (ratio 1:1) to be screened using one of the FIT systems. Our results suggest that acceptability and diagnostic performance of HM-JACKarc and of OC-Sensor systems are similar in a screening setting.

At this point we could find no evidence of overdiagnosis of CRC. While there has been a 13% increase in CRC incidence in the 60-64 age band, consistent with the first (prevalent) screening round there has been no sustained increase in the older age bands offered screening. Of note there has been an increase in incidence of rectal cancer in women under age 60.

Occult blood in faeces may be telling us about health beyond the colorectum. However, it seems likely that what it tells us about non-CRC risk might be gleaned also from other pieces of information about a patient. Future research avenues, including those proposed by Libby et al,1 will help clarify the implications of the current study. For now, I believe that our enthusiasm for the established CRC screening methods should not be affected, and that the focus after an abnormal faecal occult blood test should be to ensure prompt delivery of a follow-up colonoscopy.

This study provides detailed outcomes in men and women of different ages at a range of f-Hb cut-offs. We found differences in positivity rates, neoplasia detection rate, number needed to screen, and interval cancers in men and women and in younger and older groups. However, there are factors other than sex and age to consider when consideration is given to setting the f-Hb cut-off.

Fecal immunochemical tests (FIT) have superior adherence, usability, and accuracy as compared to gFOBT. Advantage of the use of quantitative FITs in CRC screening programs is the cut-off level that can be adjusted. […]FIT is therefore at present regarded as the preferred method of non-invasive CRC screening. This chapter will review the current status of fecal test-based CRC screening.

There was investigation related morbidity but no mortality and little to support overdiagnosis bias. The group returning falsely negative tests had a better outcome compared with the whole control group. There is a negative side to any screening programme but mortality reduction in this and other trials suggests that a national programme of colorectal cancer screening should be given consideration.