Determinants of non-participation in a mass screening program for colorectal cancer in Finland.

BACKGROUND: For an effective colorectal cancer (CRC) screening program, high participation rate is essential. However, non-participation in CRC screening program has increased in Finland. MATERIAL AND METHODS: The study was based on a population-based nationwide cohort of persons invited for CRC screening in 2004-2011. Information on the first round of the CRC screening participation and related background factors was obtained from the Finnish Cancer Registry, and information about health behavior factors from the Health Behavior Survey (HBS) in 1978-1999. Non-participation in CRC screening was analyzed with Poisson regression as incidence rate ratios (IRR) with 95% confidence intervals (95% CI). RESULTS: Of all persons invited for CRC screening (79 871 men and 80 891 women) 35% of men and 21% of women refused. Of those invited for screening, 2456 men (3.1%) and 2507 women (3.1%) were also invited to the HBS. Persons, who declined HBS, were also more likely to refuse CRC screening (men IRR 1.40, 95% CI 1.26-1.56, women 1.75, 1.52-2.02) compared to HBS participants. Never married persons had about a 75% higher risk for refusing than married ones. The youngest age group (60 years) was more likely to refuse screening than the older age groups (62 or >64 years). Smoking was associated with non-participation in screening (current smokers, men: IRR 1.32, 95% CI 1.05-1.67, women: 2.10, 1.61-2.73). CONCLUSIONS: Participation in CRC screening was affected by gender, age, and marital status. Persons, who refused the HBS, were also more likely to refuse CRC screening. Smoking was a risk factor for non-participation in CRC screening.

Effectiveness of screening for colorectal cancer with a faecal occult-blood test, in Finland.

BACKGROUND: Screening for colorectal cancer (CRC) with guaiac-based faecal occult-blood test (FOBT) has been reported to reduce CRC mortality in randomised trials in the 1990s, but not in routine screening, so far. In Finland, a large randomised study on biennial FOB screening for CRC was gradually nested as part of the routine health services from 2004. We evaluate the effectiveness of screening as a public health policy in the largest population so far reported. METHODS: We randomly allocated (1:1) men and women aged 60-69 years to those invited for screening and those not invited (controls), between 2004 and 2012. This resulted in 180 210 subjects in the screening arm and 180 282 in the control arm. In 2012, the programme covered 43% of the target age population in Finland. RESULTS: The median follow-up time was 4.5 years (maximum 8.3 years), with a total of 1.6 million person-years. The CRC incidence rate ratio between the screening and control arm was 1.11 (95% CI 1.01 to 1.23). The mortality rate ratio from CRC between the screening and control arm was 1.04 (0.84 to 1.28), respectively. The CRC mortality risk ratio was 0.88 (0.66 to 1.16) and 1.33 (0.94 to 1.87) in males and females, respectively. CONCLUSIONS: We did not find any effect in a randomised health services study of FOBT screening on CRC mortality. The substantial effect difference between males and females is inconsistent with the evidence from randomised clinical trials and with the recommendations of several international organisations. Even if our findings are still inconclusive, they highlight the importance of randomised evaluation when new health policies are implemented. TRIAL REGISTRATION: 002_2010_august.

Overdiagnosis due to breast cancer screening: updated estimates of the Helsinki service study in Finland.

BACKGROUND: Overdiagnosis is the most important adverse event of breast cancer screening with the estimates ranging from 0% to 40-50% depending on invitational age and methods. We updated the estimates of overdiagnosis in Helsinki service screening study in Finland by comparing the observed and expected cumulative incidence of all breast carcinomas and invasive breast carcinomas. METHODS: Women aged 50-59 years have been invited to Helsinki service screening since 1986. The incidence of breast carcinoma in the first invited birth cohorts born in 1935-1939 was compared with older, non-invited cohorts. The minimum follow-up time of the invitees after the last screening round was 14 years. Expected cumulative incidence rates were estimated with two alternative approaches. RESULTS: For both any breast carcinoma and invasive breast carcinoma, the estimates of overdiagnosis varied from 5% (95% CI=-1, 11%) to 7% (95% CI=1, 13%) depending on the approach. CONCLUSIONS: Our estimates of overdiagnosis are of the same magnitude than other plausible estimates in Europe. Both alternative approaches produced similar estimates for the expected cumulative incidence, which increased the confidence in the estimates of overdiagnosis.

Breast cancer mortality with varying invitational policies in organised mammography.

We examined the effect of different invitational policies on the reduction of breast cancer mortality at 60-79 years of age within the Finnish mammography programme in 1992-2003, which varied in its coverage at 60-69 years of age. The data from 260 municipalities were grouped into three categories: regular invitations at 50-59 years of age only, regular invitations at 50-69 years of age, and regular invitations at 50-59 years of age with irregular invitations at 60-69 years of age. Observed deaths from breast cancer were compared to those expected without screening among all women and among the screened and non-screened women. Observed deaths were obtained from population data and from a cohort follow-up in 1992-2003. Expected deaths were derived by modelling breast cancer mortality at population level in 1974-1985 and 1992-2003. The reduction in breast cancer mortality was strongest, 28% (0.72, 0.51-0.97), in municipalities with regular invitations at 50-69 years of age. No overall effect at 60-79 years of age was observed with regular invitations at 50-59 years of age. The study confirms a reduction by screening of breast cancer mortality in Finland. Uniform extension of invitations to 60-69 years of age would increase the number of prevented breast cancer deaths among the elderly.

Validity of process indicators of screening for breast cancer to predict mortality reduction.

The aim of the study was to empirically assess the acceptable levels of process indicators as described in the European Community Guidelines using materials from the mammography service screening programmes. The Finnish programme was evaluated for effectiveness with a prior estimate of 0.74 for RR in Finland and 0.81 in Helsinki. Hence, the Finnish programme was likely to be somewhat less effective in terms of reduction in mortality than implied on the basis of early randomized trials, but probably approaching the same level of effectiveness. Finland therefore provides background data on the applicability of the process indicators that are indicators of performance and surrogates for effectiveness. The performance data on 10 Finnish screening centres at subsequent screens were used. These centres invited 687,000 women aged 50-64 years in 1991-2000. The mean compliance was 93% and the corresponding recall rate was 2.3%. The benign to malignant biopsy ratio was 0.43:1. The average breast cancer detection rate was 0.36%, 2.1 compared with the background incidence. The proportion of screen-detected stage II+ cancers was 26%. Most, but not all, of these process indicators met the desirable reference values of the European Community. The specific criteria of the European Community on stage distribution, rates of screen-detected cancers by stage and detection rate to background incidence may need reconsideration.

Process indicators from ten centres in the Finnish breast cancer screening programme from 1991 to 2000.

The aim of this study was to evaluate the quality of the Finnish mammography programme by assessing process indicators from 10 screening centres using data from the first and subsequent screens. We compared these screen-specific indicators with European standards and results from countries with similar screening protocols. Ten Finnish centres invited approximately 1,000,000 women from 1991-2000. Women were mainly 50-64 years old. Mean compliance amongst this age group was 90% at the first and 93% at subsequent screens. The corresponding recall rates were 4.6% and 2.3%, respectively. The average breast cancer detection rates were 0.44% and 0.36%, respectively. The positive predictive values (PPVs) of mammography at the first and subsequent screens were 10% (range 7-20%) and 16% (range 12-31%), and the corresponding benign to malignant (B:M) biopsy ratios were 1:1 (range 0.5-1.8:1) and 0.4:1 (range 0.3-0.8:1). The PPV of mammography increased significantly during the study period, and the average process indicators fulfilled the criteria of the European community for the most part. However, the variation in PPVs was wide, as has been seen for other European mammography programmes, indicating meaningful differences in diagnostic criteria and potential adverse effects.