What does the use of FIT in screening for bowel cancer mean

for me and my patients?

Dr Steve SmithConsultant Clinical Biochemist

Director, Midlands & NW BCSP Hub

Faecal Immunochemical Test (FIT) in Screening

• Same test as used in symptomatic patients

• Used very differently

Analytical Ability to Detect Blood in Faeces

Manufacturer's quoted sensitivityfor gFOBT 600µgHb/g

Screening officer's sensitivity 250µgHb/g

Proposed sensitivity for FIT at implementation 120 µg Hb/g faeces

0 µg Hb/gfaeces

Limit of detection for FIT assays

SYMPTOMATICVery sensitive assays

ASYMPTOMATICBalance that is sensitive enough to detect cancers but manageable and appropriate

FIT IN SCREENING vs. SYMPTOMATIC (ENGLAND)

FIT: Probable WorkflowNHSD

HUB

Supplier

PDF list of people to be invited

Kits labelledand prepared for posting

Participants

Returned kits openedand logged

Kits tested

Invite GenerationBCSS

Logging of kitsBCSS

Episode Result BCSS

Middleware

Abnormals SSP Helpline

Result to GP

Participation in Screening

• Increased participation:

- FIT pilot showed a overall increase of 7% in uptake to 66%.

- Previous non-responders almost double uptake from 13% to 24%.*

• Role of primary care crucial in capitalising on these benefits of FIT

- Continue with initiatives to improve participation

*Moss S, et al., Gut ; 2017, 66,1631

Length of Screening Round

• Screening rounds are likely to be shorter

- Peak time taken to return a kit reduces from 14 days to 7 or 8 days.*

• Current test requires 2 samples from 3 motions. FIT only requires 1 sample.

• Less people will require more than one kit as simpler screening process with no unclear results.

• *FIT pilot data

Quicker and Simpler0

.05

.1.1

5

7 14 21 28 35 42 50 7 14 21 28 35 42 50

gFOBt FIT

Den

sity

time to resultGraphs by fit

Quicker and Simpler• Only one sample required

• Sample collection device simpler

FIT Collection Devices

Sample Stability

• Time from sample collection to analysis critical.

• Very important that participants:

- Put sample collection date on tubes

- Post back to the Hub as quickly as possible after collection

• Repeat sampling devices sent out when:

- Sample collection to receipt in lab is >10days

- No date on sample and it was sent to participant >10 days prior to receipt in the Hub.

FIT Collection Devices

Less Repeat Tests• FIT tests are specific for human haemoglobin.

• Dietary interference eliminated.

Current test detects the presence of haematin which is the same in all mammals

FIT detects the protein chains which are species specific.

Current Screening Algorithm

Retest

NormalRECALL

in 2 Years up to age 74

COLONOSCOPY

UNCLEAR ABNORMALNORMAL

Retest

Normal Abnormal

Abnormal

Screening Algorithm FIT

Normal Abnormal

Rescreen in 2 Years

SSP & Colonoscopy

Impact

• More participants

• More abnormal results

• More cancers and adenomas detected

Impact of FIT Moss S, et al., Gut ; 2017, 66,1631

Impact: Age and Sex Moss S, et al., Gut ; 2017, 66,1631

7.9%

1.7% 1.56%

At this threshold FIT will yield approximately 1.5 to 2 abnormal results where the

current test gave 1

Moss S, et al., Gut ; 2017, 66,1631

Cancer Detection by FIT Threshold*Moss S, et al., Gut ; 2017, 66,1631

%

CCooper JA, et al. Br J Cancer 2018 118 285

False Negatives• At any threshold there will still be FALSE NEGATIVES

• Result letter will still advise people about symptoms

and seeking help.

• A normal screening result DOES NOT exclude bowel cancer it only reduces the risk of it being present.

• Really important that anyone with symptoms but an earlier NORMAL screening result is properly investigated.• Patient with previous Normal screen now meets NICE

criteria for symptomatic FIT should get a FIT test.

False Negatives: Why?

• Sampling• Stools are not homogeneous

• Haemoglobin degradation in vivo • Screening does not appear to detect proximal tumours

as well as distal ones.

• Anaemia?• Person may be bleeding but insufficient haemoglobin

• Are lesions bleeding continuously?

Future Developments

• Reduce the FIT threshold• Increase cancer and adenoma detection BUT increase

colonoscopy and pathology demands

• Refine the use of FIT• Simple adjustments to result calculation

• Adjust for gender

• Females appear to have less blood in faeces

• Adjust for age

• Older people appear to have more blood in faeces

Future Developments

• More Complex Adjustments using neural networks/artificial intelligence

• Previous screening result

• Difference between results

• Trend

• IMD

• Less affluent at greater risk for colorectal cancer

Future Developments

CCooper JA, et al. Br J Cancer 2018 118 285

Future Developments

• Reduction in screening age to add the 50 to 59 year olds:• When?

• How?

• Continuation of BowelScope?

Resources:

• Cancer Research UK Health Professional webpage bowel screening evidence and FIT test.

https://www.cancerresearchuk.org/health-professional/screening/bowel-screening-evidence-and-resources/faecal-immunochemical-test-fit

• Contact a CRUK Health Professional Facilitator to arrange a practice visit.

https://www.cancerresearchuk.org/health-professional/learning-and-support/tailored-help-for-gp-practice

• Bowel screening resources/GP good practice guideshttps://www.cancerresearchuk.org/health-professional/screening/bowel-screening-evidence-and-resources/bowel-screening-resources