Screening programs for colorectal cancer in Greece: Results of two pilot studies conducted in March 2008 and 2009

Abstract

Background: Detection of occult blood in stools is an established method for the early detection of colorectal cancer in asymptomatic individuals of average risk. The aim of this study was to present the results derived from the application of the test in a cohort of Greek population of average risk. Subjects and Methods: We conducted two pilot studies in March 2008 and 2009 respectively. The first was conducted only in the greater area of Athens while the second one included two more major cities in the North and South part of the country (Salonika and Iraklion, Crete). In both campaigns all residents, aged between 55 and 72 years were asked through relevant television spots, articles in newspapers, radio spots and press conferences to participate in both studies (March 2008 and March 2009), by submitting a stool sample in the nearest "Biomedicine" Laboratory. For the detection of haemoglobin in stools LINEAR immunochemical FOBT was applied. This test is a qualitative, lateral flow immunoassay for the detection of human hemoglobin in stools. In order to include in the statistical analysis more than 90% of all examined individuals, we divided the number of subjects participating in the 2009 trial into three groups aged 55-60, 61-66, and 67-72 years. Moreover, in order to be able to calculate the odds ratios, these groups were transformed from numerical to nominal ones. Statistical analysis was performed using Pearson chi square test. Results: 1st trial, March 2008: The total number of individuals examined was 4,010. The rate of positivity was 9.83% (394 out of 4,010 individuals examined). Among the positive samples 30.2% corresponded to subjects aged 55- 60 years, 35.3% to subjects aged 61-65 years and 34.5% to subjects aged 65-70 years. 2nd trial, March 2009: The total number of individuals tested was 7,079 with 3,131(44.2%) being men and 3948(55.8%) being women. The participation rate was: Athens 5,037 (71.1%), Salonika 1,407 (19.9%) and Iraklion 635 subjects (9.0%). The positivity rate was 11.1% (786 out of 7,079 subjects). The positivity rate among men (11.9%) (373/3,131) was higher compared to women (10.5%) (413/3,948) although this difference did not reach statistical significance (P=0.057). Mean age of the positive subjects was statistically significantly higher compared to negative ones (62.4 vs 61.9yrs, P=0.01). Significant differences existed between group 1 (55-60 years) vs group 3 (67-72 years). So, the probability of a positive test in the age of 67-72 was 1.36 times higher than at the age of 55-60 and the probability of a positive test in the age of 67-72 was 1.26 times higher than at the age of 61-66. Statistically significant difference in the positivity rate of the test between the three areas was noticed. So, residence was responsible for the variation in positive rate of FOBT by 6.9% (Eta statistics). Conclusion:The rate of positivity of iFOBT in Greece is in accordance with that reported in the relevant international literature and remains steady, at least during the years 2008 and 2009. However, it seems to be lower in areas adopting the so called Mediterranean diet (Iraklion, Crete). Taking into account the number of inhabitants of the country over the age of 55, we can assume that the compliance of the Greek population in colorectal cancer screening programs is relatively low. In the forthcoming years, screening programs in Greece must be adopted by the health authorities of the country in order to cover a larger part of the population. The experience derived from our studies could result in more successive and productive future programs.