RESULTS OF A COLORECTAL SCREENING PROGRAMME BELOW THE FIT THRESHOLD OF 100 NG/ML (20UG/G)

Aims:

The CRC screening programmes based on the immunological FOBT/FIT (faecal occult blood test) among asymptomatic subjects between 50 – 69 years old have proved its efficacy in the reduction of CRC incidence and mortality. The threshold to consider a FIT positive in the Spanish CRC screening programme and therefore be invited to undergo colonoscopy is 100 ng/ml. Considering that values above 50 ng/mL are considered positive out of the screening programme, there is a % of asymptomatic subjects with values between 50 – 99 ng/mL that could have undetected lesions.

Aim:

TO ANALYSE THE ENDOSCOPIC FINDINGS IN PATIENTS WITH FIT RESULTS BETWEEN 50 – 99 NG/ML.

Tab. 1:

Comparative of endoscopic findings FIT50 – 99 vs. FIT> 100

	Screening group (FIT> 100)	FIT 50 – 99	p value
Adenomas: Total/Male/Female	879 (69.2%)/557 (74.9%)/322 (61.2%)	32 (45.7%)/17 (54.8%)/15 (38.5%)	0,00/0,13/0,05
High risk adenomas: Total/Male/Female	608 (47.9%)/426 (57.3%)/182 (34.6%)	14 (20%)/10 (32.3%)/4 (10.3%)	0,00/0,05/0,01
CRC: Total/Male/Female	105 (8.3%)/71 (9,3%)/34 (6,5%)	2 (2.9%)/1 (3.3%)/1 (2.6%)	0,074/0,212/0,285
Age (years)	65.27	65.47	0,705

Methods:

We analysed retrospectively FIT results (OC-SENSOR, Biogen) received in the laboratory of León's Hospital in the first round of CRC screening between 2014 – 2016. We selected those patients with FIT results between 50 – 99 that had undergone colonoscopy by their doctor's indication as screening. As a control group, we used subjects that undergone colonoscopy as part of the CRC screening programme (FIT ≥100).

Results:

A total of 989 subjects between 60 – 69 years old presented FIT results ranging from 50 to 99 ng/mL.70 (7%) of them underwent colonoscopy. We detected adenomas in 32 (45.7%), high risk adenomas in 14 (20%) and CRC in 2 (2,9%). In the indexed table, we present the results comparing with the control group.

Conclusions:

The FIT threshold established for the populational CRC screening in Spain is efficient, but it can increase the false negative (FN) situations. It is necessary to evaluate these results with larger series to find the risk factors associated to FN as well as allow us to propose evidence-based changes to the threshold or modifications to the screening interval.