Pathology
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Colorectal cancer (CRC), the second most common cause of cancer-related mortality worldwide, is preventable with effective screening and removal of precursor lesions. Yet, screening efforts have been hampered by low participation rates and by performance limitations of the screening tools themselves. Stool DNA testing has emerged as a biologically rational and user-friendly strategy for the non-invasive detection of both CRC and critical precursor lesions. ⋯ Based on recent studies, advanced multi-marker stool DNA tests including methylated markers, mutation markers and an assessment of faecal haemoglobin have been shown to detect CRC at sensitivities of 85% and higher and adenomas >1 cm at 60% and higher in a case-control environment. If the high accuracy of multi-marker stool tests is corroborated in multicentre screening studies on average-risk persons currently underway, then these stool tests could influence our CRC screening paradigm. This review discusses the biological basis, key technical advances, and recent clinical performance validation of stool DNA testing.
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The high global prevalence of iodine deficiency and autoimmune thyroid disorders and the mental and physical consequences of these disorders creates a huge human and economic burden that can be prevented, in large part, by early detection and appropriate preventative or therapeutic measures. The availability of sophisticated, sensitive and accurate laboratory testing procedures provides an efficient and effective platform for the application of screening for these disorders. Measurement of urine iodine concentration (UIC) in school children or pregnant women is the recommended indicator for screening populations for iodine deficiency. ⋯ Because of the limitations of targeted case detection in women at risk of subclinical hypothyroidism, there has been a gradual shift in opinion to universal TSH screening of all women as soon as practicable in pregnancy. While a positive association exists between the presence of anti-thyroid antibodies and increased pregnancy loss, universal screening of all pregnant women for underlying autoimmune thyroid disease is difficult to justify until there is evidence of beneficial outcomes from randomised controlled trials. Vigorous and liberal targeted case detection remains the recommended strategy to address this problem.
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Prostate cancer is a slowly progressing but potentially lethal disease. In order to cure it we must detect it while it remains organ confined. Because of the slow course of the disease, prostate cancer screening trials take a long time to show any benefit and in that time the measurement and interpretation of prostate specific antigen (PSA) concentrations have changed, and biopsy and treatment protocols have also developed. ⋯ Improvements in the specificity of PSA include age-related PSA reference limits, free to total PSA ratio and PSA dynamics such as doubling time. Improvements in sensitivity have progressed to defining that we should focus on the 50% of men with PSA concentrations above their population median, as men with PSA below the median are very unlikely to develop or suffer from prostate cancer. Like any medical procedure, men should be informed of the risks and benefits but this should ideally be done in a manner that encourages informed choice based on their own understanding and feelings, rather than informed compliance based on the views of others.