Hadjisavvas et al. BMC Cancer 2010, 10:447 http://www.biomedcentral.com/1471-2407/10/447 emphasized the importance of genetic factors, but it is currently believed that environmental factors are of greater significance [10]. Cyprus is the third largest island in the Mediterranean Sea with a Greek-Cypriot population of 749,200 as recorded in July 2004, by the statistical service of the Republic of Cyprus. Data from the National Cancer Reg- istry established in 1998 by the Ministry of Health show an average incidence of 400 female breast cancer cases per year [11]. This corresponds to an age-standardized incidence rate of breast cancer of 60 per 100,000 popu- lation [11] which is comparable to the rates seen in other Southern European countries, a region where a moderate breast cancer risk is usually recorded [6]. Cyprus is a member of the European Union since 2004, and has a long history of practicing a Mediterranean lifestyle. However the lifestyle is rapidly changing towards a western type of life, so it is of interest to study the pattern as well as the influence of breast cancer risk factors in our population. Indeed, there are no data as yet available about breast cancer risk factors in the Cypriot female population. The main aims of this report are (a) to describe the background levels of established and recognized breast cancer risk factors among Cypriot women and (b) to assess the strength of their association with breast can- cer risk. In order to achieve this we carried out a case- control study, involving a breast cancer patient group and a control group of healthy Cypriot women attending mammography clinics as part of the National screening programme. A number of risk factors that modulate breast cancer such as socioeconomic status, reproduc- tive events, family history and lifestyle factors were investigated. Interestingly, previous published work by our group has shown that the Cypriot population exhibits some unique genetic features as revealed by the identification of novel mutations in the BRCA1 and BRCA2 genes [12,13]. Moreover, this is the first study into breast can- cer epidemiology among the Cypriot female population and will function as a baseline, of future efforts into combining person-based data, with the molecular/ genetic data in order to study gene-environment interac- tions in our population. Methods Study participants and data collection The sample size was determined using power calcula- tions in order to ensure at least 90% power to detect a magnitude of association at the odds ratio scale of 1.5 at 5% statistical significance for an exposure that occurs among 10% of the controls. The cases consisted of 1109 women, between 40-70 years of age who had a histologi- cally confirmed diagnosis of primary breast cancer Page 2 of 10 between January 1999 and December of 2005. Younger cases were excluded since in addition to the fact that early-onset breast cancer may share a different aetiology, the source of the controls (i.e. mammography screening users) only effectively covers women in this age range. During the study period (January 2004 - December 2006), breast cancer cases that fulfilled the above criteria were approached while waiting for their oncologist appointment and were given an introductory letter out- lining the goals of the study. Those who agreed to parti- cipate in the study subsequently underwent a personal interview with a trained interviewer. The majority of cases were ascertained from the Bank of Cyprus Oncol- ogy Centre, which operates as a referral centre and offers treatment and follow-up for up to 90% of all breast cancer cases diagnosed in Cyprus. The rest of the patients, were recruited at the Oncology Departments of the Nicosia, Limassol, Larnaca and Paphos district hospitals. The control group consisted of 1177 Cypriot women from the general population, who were invited to parti- cipate in the National programme for breast cancer screening with the use of mammography and received a negative result. Volunteers were enrolled in the study during the same calendar period as the cases, from the 5-district mammography screening centers that operate in Cyprus. Due to the narrow age span of women invited for screening (ages 50-69) younger and older women were underrepresented. Nevertheless, between the ages of 50-65, the observed age distribution roughly matched the age structure of the island’s female popula- tion. Women were approached while waiting for their mammography appointment and were given an intro- ductory letter outlining the goals of the study. Those who agreed to participate in the study subsequently underwent a personal interview with a well trained interviewer. Demographic and risk factor data were collected from both cases and controls with the use of a specially designed questionnaire, through a standardized inter- view. The questionnaire used in the present study was primarily based on a similar questionnaire used in the East Anglia breast cancer study [14]. The study was approved by the Cyprus National Bioethics Committee. Each participant gave written consent and the data were anonymised and coded into an MS ACCESS database. The questionnaire included information on age, marital status, level of education, current BMI, exercise status, smoking status (i.e. never, past, current smokers), family history of breast cancer (i.e. first degree relatives), use of hormone replacement therapy and a range of reproduc- tive characteristics such as age at menarche, any preg- nancy, gestation period, parity, overall duration of breastfeeding, use of oral contraceptives, age at first and