Breast, colon, and prostate screening in the adult population of Croatia: does rural origin matter?

BACKGROUND. The aim of this study was to investigate the utilization of breast, colon and prostate cancer screening in the adult Croatian population during a period without implemented national cancer screening programme, with a special interest in the rural vs. urban respondent’s origin. METHODS. Self-reported screening utilization was investigated in the Croatian Adult Health Survey, which collected health related information from the representative sample of the adult Croatian population. Breast cancer screening was investigated in women aged over 40, while colon and prostate in respondents aged over 50. The data were analysed with binary logistic regression. RESULTS. One in five women reported a breast cancer screening uptake in the year preceding the survey (22.5%), while only 4.5% reported colon screening. A total of 6.1% men reported colon screening, while 13.7% of men reported having a prostate cancer screening. Respondents with rural origin reported all sites screening utilization less frequently than those with urban origin (breast 14.5% vs. 27.4%; prostate 9.6% vs. 16.3%; colon-men 5.7% vs. 6.3%; colon-women 3.6% vs. 5.1%; all rural vs. urban). Multivariable models indicated that people with higher socio-economic status more commonly reported breast and prostate cancer screening uptake. Access to health care was the only independent variable associated with colon cancer screening in men, and the strongest variable associated with colon cancer screening in women. Rural origin was associated only with lower odds of breast screening (adjusted odds ratio 0.60 [95% confidence interval 0.48-0.74]), while in the remaining models rural origin was not a significant predictor for cancer screening uptake. CONCLUSIONS. Opportunistic cancer screening uptake is low in Croatian adult population, with existing socio-economic differences in breast and prostate screening, and their absence in colon cancer screening. Rural origin was significantly associated with breast screening, even after adjustment to socioeconomic status and problems in access to health care. Lack of rural origin significance in the other screening sites could be related to small sample sizes of people who reported opportunistic utilization of these screening sites. Overall conclusion suggests that the access to health care is the strongest cancer screening predictor, and that it should


Introduction
Social disparities in cancer present an interesting challenge.
This research area has received much attention, but there are still some basic misconceptions, even in the case of the phrase 'cancer disparities' 1 .Summarized results of this research area suggest that social disparities in cancer remain serious and persistent, despite major advances in the extent, determinants, treatment and prevention of cancer 2 .In an attempt to further disentangle cancer development mechanisms, three large factor groups were identified: (i) cumulative economic deprivation; (ii) exposure, susceptibility and resistance across the life course; and (iii) gene expression, not just gene frequency 1 .
Screening is an important tool for early cancer detection and consecutive mortality reduction.Various countries have differing guidelines, and varying policy implications for cancer screening programs (in both screening frequency and the respondent's age).Despite these efforts, a number of studies have shown that socio-economic determinants have an important role in actual screening uptake.An association between higher socioeconomic status and more frequent screening utilization has been described in the cases of breast 3,4 , prostate [5][6][7] and colon cancer screening 4,8 .A study from California suggests that a decrease in colon and rectal cancer incidence may be related to wide-spread screening, especially among non-Hispanic white men and women who are considered to be the highest socio-economic group 9 .
Additionally, it seems that rural origin has an important effect on the breast cancer screening uptake 3 , even after adjustment to socioeconomic factors.
The aim of this study was to investigate social disparities in breast, colon and prostate cancer screening in a sample of the adult Croatian population, with a special interest in the rural versus urban respondent's origin.

Setting
We investigated breast, colon and prostate cancer screening in a sample of the adult Croatian population.Data from the Croatian Adult Health Survey 2003 were used.

Croatian Adult Health Survey
The Croatian Adult Health Survey (CAHS) was designed to be a periodic survey of the Croatian population, aiming to provide surveillance of various risk factors 12,13

Statistical analysis
Analysis was performed in SAS 8.0.2 (SAS; Carry, NC, USA), with bootstrapping variance estimation performed by the Bootvare_sas.v20 12 .All results were presented as weighted estimates for the entire Croatian population.

Coefficient of variation (CV) was used as a variation
indicator for the weighted screening estimates.The CV values of less than 16.6 were considered optimal; those between 16.6 and 33.3 were considered to reflect a greater extent of variation; while estimates over 33.  1).More frequent breast cancer screening uptake was reported by women in white-collar occupations and those from urban areas (Table 1).Similar results were recorded in prostate cancer screening in men, with less clear differences (Table 1).The oldest age group reported prostate screening most commonly, although a higher coefficient of variation was recorded for this estimate (Table 1).All differences in colon screening in both genders were less marked, sometimes without clear differences.The 60-69 years age group in both genders reported peak onset for colon screening (Table 1).Screening utilization was systematically less commonly reported by respondents with a rural origin, compared with those of urban origin (Table 1).
A multivariable model of the self-reported breast cancer screening indicated that most of the investigated variables were significantly associated with screening uptake, except for lower education and occupation classes (Table 2).The respondent's age, two classes of educational level, occupation and access to health care were significantly associated with prostate screening (Table 2).Access to health care was the only significant independent variable associated with colon screening in men (Table 3).Women coming from households with the highest incomes, and those who reported having no problems in access to health care most often reported having a colon screening within the last year (Table 3).

Discussion
The Social disparities in breast cancer screening have been extensively described, usually reporting the worst indices among women from lower socioeconomic classes 3 .These women are less likely to respond to a screening invitation 14,15 , and they are at an increased risk of late-stage breast cancer diagnosis 16 .Interestingly, disparities in breast cancer screening remained even in a setting with continuity of health care 17 .Rural origin is a factor that has been associated with lesser probabilities of breast screening uptake 3 , although this finding does not seem to be universal 18 .The results of another study suggest that rural origin is not, of itself, a crucial negative breast cancer screening predictor, but an element of a much finer interplay of various factors 19 .The results of the present study contradict such a finding, because a lesser incidence of breast screening in rural women remained even after controlling for the most obvious confounding factors, general lower socio-economic status, older age of rural women, and difficulties in accessing the healthcare facilities.Access to health care was a significant predictor of breast cancer screening in the present study, supporting some previous findings 20 .It has been implied that this is one of the most important factors for breast screening in limitedresource settings 21 .However, other studies suggest that, even in settings with the same access to mammography, women from lower socioeconomic classes were less likely to use this screening 22 .Overall findings from the present study supported clear socioeconomic differences in self-reported breast cancer screening uptake, suggesting that women from higher socioeconomic classes in Croatia are most likely to receive opportunistic breast screening.In contrast to breast cancer screening, the overall effectiveness of prostate screening is far less convincing.

Screening type
There is still no consensus as to whether prostate screening is effective 23 , with some studies suggesting that screening for prostate cancer cannot be justified in low-risk populations 24 .
Nevertheless, more frequent screening utilization among men of higher socioeconomic status has been implied in a number of studies 5,6 , even suggesting that when ethnic differences were diluted the socioeconomic differences persisted 25 .The current study also supports more frequent screening utilization among men from higher socioeconomic classes, but with less clear differences than those for breast cancer screening in women.It is worth noting that respondents of rural origin had lower odds ratio of prostate screening in the multivariable analysis, but that these differences were not statistically significant.for people over 50 years 27 .
The shortcomings of this study include the use of selfreported survey data, and the use of broad and unspecified questions.The use of targeted questions (on types of screening) supplemented with medical records would produce more precise estimates, and reduce the possibility of reporting diagnostic and therapeutic examinations as screening.There is an additional problem in colon cancer screening models, because some studies suggest that in systems with universal access to health care, approximately two-thirds of colonoscopies were performed due to known symptoms, while only one-third were performed as screening 28 .

Conclusions
This study reports an unsatisfactory cancer screening uptake among the adult population of Croatia.While we may speculate whether this situation occurred as a consequence of the war or health system transition, the increasing trend in cancer incidence and mortality continues.People with higher socioeconomic status more often reported breast and prostate screening; however, no association of socioeconomic status with colon cancer screening was detected.Rural origin was negatively associated with breast screening uptake, while the results from the other screening sites were less convincing.
Overall results suggest that ensuring easier access to screening could increase the frequency of screening services utilization, with a final goal of cancer burden reduction.
white-or blue-collar occupations).Rural versus urban origin was assessed by the respondent's permanent address, according to the rural versus urban location classification from the Central Bureau of Statistics and the Governmental classification of the rural and urban settlements.Additionally, subjective healthcare access estimates were calculated.Respondents had the opportunity to score the accessibility of their general practitioner, polyclinic and hospital from 1 to 3 (1 = no problems; 2 = moderate; and 3 = a substantial problem in healthcare access).Respondents who scored at least 6 points when all three variables were summed were considered to have a healthcare access problem.Health insurance was not included as an independent variable because there is almost complete obligatory health insurance coverage in Croatia.
results of this study indicate infrequent utilization of cancer related screening in the adult Croatian population.The effects of post-war health system transition or the lack of national screening programs may have contributed to the current situation.There are, however, some preventive local actions (such as 'breast cancer awareness day'), or nonsystematic screening efforts (such as the 'mobile mammography project', which aims to reach population fractions who have difficulty in accessing health care).In this situation, the effects of socio-economic determinants and a respondent's urban origin could hypothetically be even more pronounced than in other countries that have implemented systematic screening programs, because people have more individual responsibility in screening services utilization (combined with recommendations from their physicians).

Table 2 : Logistic regression models of breast and prostate screenings during the year preceding the survey, from the Croatian Adult Health Survey 2003 sample Kn
, Croatian currency: Kuna; OR, odds ratio; Ref, referent group.