Find out more at www.faecal-immunochemical-test.co.uk 9 Using this FIT cut-off most ‘IBS’ patients and those with diminutive polyps will be spared, initially at least, investigation. But FIT will miss half of those with organic enteric disease, over half of those with significant polyps and, importantly, half of those with other non-enteric cancers. So clearly FIT is a game changer. But not perfect. If you apply FIT using 10 µg/g cut off [Figure 1], the proportion of missed CRC will double. But, the numbers will still be very small. Three patients in 1000 will be missed who would have been picked up using FIT for ‘detectable’ haemoglobin. But you will have reduced the number of FIT positive patients with IBS to a third. The total number of patients with a positive FIT will now be 140 patients. This then allows you to start to use healthcare resource much more efficiently. You have the starting potential to spare 860 patient investigations from the original 1000 patient cohort. That resource can be directed at other patient groups, such as those fulfilling NICE DG30. Our findings suggest that using the FIT ≥10µg/g cut off you get the optimal sensitivity (82%) and specificity (88%), with a high NPV (99%) and an acceptable PPV (27%). FIT NEGATIVE PATIENTS So I have made the presumption that FIT negative care begins when a high risk patient has one FIT <10 µg/g. In our putative population of 1000 patients we now have 860 such patients and within this group <1% will have CRC, 3% will have significant polyps and 3% non-CRC cancer. A significant number of patients with organic enteric disease will remain, but over 90% will have ‘IBS’. What do we do next? What if you repeat the FIT or add in a fCAL? If you repeat the FIT and you are looking solely for CRC you will want either of, rather than both, of the two FIT to be positive (to ‘rule in’ not ‘rule out’). In so doing we found that you could marginally increase the sensitivity and specificity of FIT, but not significantly. Furthermore the repeat FIT requires additional cost, time and may reduce patient compliance. We conclude that in symptomatic patients at high risk, a repeat FIT prior to referral would fail to detect CRC in those who were initially FIT negative. Perhaps their biology is different. Two FITs may prove useful for screening (it may offer cost savings) but not in the work up of symptomatic patients. Adding fCAL gives no diagnostic advantage because it reduces the PPV. Can you identify the FIT negative patients with CRC if you apply particular patient symptomatology? The short answer here is no. Symptoms are no less specific in FIT negative patients than they are in the unselected cohort. Neither are we currently able to improve the sensitivity and specificity of FIT based on symptomatology (although this may come). Currently for example FIT cannot be applied in the low risk population (DG30) where there is rectal bleeding. However we found no difference in those presenting with or without rectal bleeding. Managing FIT negative patients for the future In thinking about the negative FIT we need to leave the technology behind and return to the patient. Perhaps we need to look again at NICE CG27, the NICE guidance that pre-dated NG12. Here it states that ‘in patients with equivocal symptoms who are not unduly anxious, it is reasonable to use a period of ‘treat, watch and wait’ as a method of management’. Quite what this will mean in practice is as yet uncertain. But the majority of patients will have functional disease and some will settle with expectant management. As many as 90% of younger, low risk patients will respond to local supportive measures but it is uncertain how many will do so in this population. Perhaps 50%, optimistically. So the key question is whether we will give this disparate group of patients, time to declare themselves. Will we treat them expectantly or will they all be sent for abdominal-pelvic CT scans to find the non-enteric cancer in a newly defined suspected cancer pathway? Surely for FIT to be of any health economic benefit the clinician must be able both to apply clinical judgment if suspicious and so refer into a two week wait pathway, even if FIT negative, but also to treat symptomatically and review locally if judged appropriate. In this way patient care is central and FIT supports the efficient use of resource. And who is going to carry that risk? Will primary care carry this cohort of FIT negative patients in whom it is known that there is missed cancer and in whom referral would otherwise have taken place if NICE NG12 were applied? Should GPs refer all patients anyway, FIT positive or negative alike, but the former urgently and the latter routinely? Or perhaps GPs should both retain clinical suspicion and initial management decision; treating FIT negative patients symptomatically without automatic referral. Some would be referred urgently and others routinely should they remain symptomatic or early if suspicion was high. Would CT requesting from primary care become the norm? In my mind what is needed is for clinical suspicion to help safety-net the patient and this would be my preferred option. continued.... Figure 1: Applying FIT using a cut off of 10µg/g
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