[Some insufficiently recognized risk factors for breast cancer].

INTRODUCTION In the most developed countries female breast cancer is the main cause of death due to the most common malignancy in women [1]. Over the period 1975-1982 and 1982-1991 women in Serbia died most frequently of malignant tumours of the breast [2, 3]. A tendency to increase mortality rate of the disease was recorded in this period. The aim of this paper was to determine the importance of some insufficiently known breast cancer risk factors. MATERIAL AND METHODS The study was based on a case-control study conducted from July 1993 to March 1994. The patients were selected at the Department of Oncology in Nish, and included 106 female patients with histologically documented breast cancer (a two-year diagnosis). Controls were individually matched to patients by age (+/-3 years) and number of patients with mild injuries, hospitalized at the Clinical Centre in Nish. All the examined subjects, from both groups, were interviewed by the same doctor using a target and detailed questionnaire about different risk factors of breast cancer. McNemar test was used in the study. RESULTS The results are presented in Table 1. The results confirmed a significant positive association between breast cancer risk and psychological stressogenic events (RR = 4.40 95% CI = 2.30-8.40 p = 0.0000). With reference to a previous history of mastitis, a frequent positive history was found in the examined patients and it was statistically significant (RR = 7.50 95% CI = 2.99-18.83 p = 0.000). The risk of developing breast cancer was strongly related to alcohol consumption (RR = 4.11 95% CI = 2.05-8.24 p = 0.0001). Two environmental factors were significantly associated with breast cancer: occupational exposure to organic dust (RR = 3.80 95% CI = 1.41-10.20 p = 0.0066) and to pesticides (RR = 4.25 95% CI = 1.43-12.58 p = 0.0072). DISCUSSION In our patients stressful life-events were significantly frequent. Most of them reported death or a serious illness of the spouse or of a close family member, marital divorce, son's military service, etc., within the two years prior to the disease. The evidences related to the possible role of stressful life-events in mammary tumorigenesis are insufficient and controversial. Becker [4] suggested that separation from parents before fourteen, marital problems and death of the husband correlated positively with breast cancer risk. For et al. [5] observed that a cancer group had a higher proportion of women who experienced death of the spouse or of a close family member. In contrast, the results of one recent study [6] confirmed no clear evidence that death of the husband or marital divorce were associated with an increased risk of breast cancer. Further investigation of the role of stress in the onset of breast cancer should take into account not only the number of stressful life-events, but also the personality of an individual and effect on her ability to cope with stress [7]. As in many studies [8-11], but not in all [12-14], our results suggested a significant positive association between breast cancer risk and alcohol consumption. Studies have indicated that the increased risk is associated with the type of beverage used [15], the level of consumption [11], but not with the years of consumption [8, 11, 16]. Alcohol consumption at an early age [17] and at the late age [16] increase the risk of breast cancer. Although certain biologic mechanisms for this association have been suggested, such as interference with the cell membrane permeability in breast tissue, exposure to circulating cytotoxic products of ethanol and altered hepatic function, none is generally accepted [17]. The question remains as to whether the increased risk is attributable to alcohol or to some other characteristics in women who drink alcoholic beverages compared with those who do not. We observed a positive correlation among breast cancer risk related to a positive history of mastitis, occupational exposure to organic dust and to pesticides.