Incidence variation of prostate and cervical cancer according to socioeconomic level in the Girona Health Region

Gemma Renart Vicens 0 Marc Saez Zafra 0 Judit Moreno-Crespi 2 Bernat C Serd Ferrer 1 Rafael Marcos-Gragera 2 0 Research Group on Statistics, Applied Economics and Health (GRECS), CIBER of Epidemiology and Public Health (CIBERESP), University of Girona, Campus de Montilivi , Girona 17071 , Spain 1 Departament d'Infermeria. Universitat de Girona (UdG), Girona Biomedical Research Institute , Girona , Spain 2 Epidemiology Unit and Girona Cancer Registry, Oncology Coordination Plan, Department of Health, Autonomous Government of Catalonia, Catalan Institute of Oncology, Girona Biomedical Research Institute , Girona , Spain Background: The main aim of this study, using a spatial-temporal model, is to analyse the link between a deprivation index and the incidence of prostate and cervical cancer in the Girona Health Region (GHR). Methods: This is a population-based study which includes all the inhabitants in the GHR in the period 1993-2006. In order to assess prostate/cervical cancer risk, Besag, York and Mollie (BYM)'s spatial-temporal version of the model was used and four random effects were introduced: (non-spatial) unstructured variability, spatial dependency, temporal dependency and spatial-temporal interaction. As an explanatory variable, a deprivation index was introduced at the census tract level. Furthermore, the percentage of the population between 45-64 years of age and over-65 was also considered as explanatory variables. Results: In the case of prostate cancer, all the variables which were introduced into the model showed a significant correlation with the relative risk, except for the second quintile of the deprivation index. Furthermore, as the index increased the correlation became negative and lower. Thus, the correlation between the relative risk and the two age bands proved to be lower, the higher the age was. In the case of cervical cancer, only the correlation between the over-65 age band and the relative risk was found to be statistically significant and positive. Conclusions: In the case of prostate cancer, the results obtained in the GHR are in line with similar analyses. However, in the case of cervical cancer, no significant relationship between incidences in this location or economic status was found. - Background The study of incidence and mortality in small areas and their relationship with different socioeconomic indicators has recently been attracting a growing interest in different countries [1-6]. Not only can individual factors explain the causes of the disease, but so too must the contextual factors of the area of residence be taken into account, particularly in small areas, as those characteristics may contribute to the socioeconomic and environmental differences in health. In the case of cancer, there are various studies which show how the contextual factors of place (i.e. area of residence) can have an effect not only the incidence of cancer, but also on mortality rates. It would appear that the most disadvantaged areas tend to have higher mortality rates [1,3,5-8]. This study focuses on this relationship for the particular cases of prostate cancer and cervical cancer. According to Ferlay et al., 2013 [9] when both sexes are combined prostate cancer is the fourth most common cancer and the second most frequently occurring cancer in men, while cervical cancer is the fourth most commonly occurring cancer in women and the seventh most frequent overall. Prostate cancer is the second most common cancer in European men and represents approximately 12.1% of all newly diagnosed cancer cases [9]. In Europe, incidence rates vary greatly. The highest rates were estimated in northern and western European countries (such as Norway and France) and the lowest in the central and eastern European countries (e.g. Republic of Moldova and Albania) [9]. In Spain prostate cancer, ahead of lung cancer, is the most common tumour found in men. Approximately 20,000 cases per year are diagnosed, which represents 21% of all tumours among men [9]. The estimated incidence rate for the Spanish population in 2012 is 96.8 cases per 100.000 males [9] and so is similar to other developed countries. In the case of the GHR, the incidence rate is estimated to be 97.6 cases per 100 000 males per year [10,11]. In the majority of cases, a diagnosis of prostate cancer occurs between 60 and 80 years of age, although there are a significant number of cases from 50 years of age onwards, with the average age being 69. In general, prostate cancer may be considered to be a tumour which is more typical in older men [12]. Since the introduction of the Prostate Specific Antigen screening in Spain, the rate of diagnosis has increased significantly but the specific mortality rate has in fact decreased [13-17]. Cervical cancer is the fourth most common neoplasia among women in the world today and represents a seventh of all neoplasias [9]. As in the case of prostate cancer, there are significant differences between more and less developed countries: while in the latter case it is, after breast cancer, the second most commonly occurring tumour, in developed countries its frequency has decreased significantly in recent decades thanks to prevention and early detection strategies and campaigns [18]. 83% of the cases of cervical cancer diagnosed each year occur in developing countries [19], and are, ahead of breast cancer, the most frequent cause of death from cancer in those countries. The estimated incidence for the Spanish population is 7.69 per 100 000 women [18]. The average age at diagnosis is 48 years old, although approximately 47% of women with cervical cancer are diagnosed before the age of 35, and only 10% are diagnosed in women over the age of 65 [10]. In Spain, approximately 2 100 cases are diagnosed annually; representing 3.3% of cancers in women and with 7.6 new cases/100 000 women/year the incidence of cervical cancer may be considered one of the lowest in the world [20]. The main aim of this study, using the spatialtemporal version of the Besag, York and Mollie model [21,22], is to analyse the variation in incidence of both neoplasias according to the area of residence and in relationship to socioeconomic deprivation in the Girona Health Region (GHR). Methods Data setting The present study was undertaken within the framework of the MEDEA project and one of the objectives was to estimate the relative risks associated with a deprivation index for various cancer locations in the Girona Health Region (GHR), (which basically coincides with the Province of Girona, in the north of Catalonia, Spain), and to ascertain whether this deprivation index could explain part of the spatial variability found in some of these locations [6,23]. All the residents in the GHR (which according to the 2006 municipal population register were 670 096 inhabitants of whom 339 839 were males and 330 257 females) were considered as a study population. The study took place from 1993 to 2006, b (...truncated)