Attributable risks for breast cancer in Italy: Education, family history and reproductive and hormonal factors

Abstract

The percent population attributable risk (AR) for breast cancer was estimated in relation to education, family history of the disease and some reproductive and hormonal factors, using data from a case-control study conducted between June 1991 and February 1994 in 6 Italian centres on 2,569 histologically confirmed incident breast cancer cases and 2,588 controls, admitted to hospital for a wide range of acute, nonneoplastic, non-hormone-related diseases. On the basis of multivariate odds ratios, a high level of education accounted for 20% of cases, elevated age at first birth and nulliparity for 38% and a family history of breast cancer in first-degree relatives for 7%. Education and nulliparity and age at first birth together explained 47% of all breast cancer cases, and the combination of these 2 factors plus a family history of the disease explained 50% of cases. In pre-menopausal women a high level of education accounted for 31% of all breast cancer cases, older age at first birth for 44% and the combination of the 2 factors for 49%. In post-menopausal women the corresponding values were 13%, 31% and 42%; further addition of risk associated with family history of the disease explained 52% of pre-menopausal cases. In post-menopausal women older age at menopause and the use of hormone replacement therapy accounted for 15% and 2% of breast cancer cases, respectively. The combination of risks associated with a high level of education, old age at first birth and nulliparity and older age at menopause accounted for 51% of cases; further inclusion of risk associated with use of hormone replacement therapy explained 52%, and the AR resulting from these 4 risk factors combined plus a family history of breast cancer was 56%. Thus, a few selected and well-identified risk factors explain about one-half the breast cancer cases in this Italian population. Int. J. Cancer, 70:159-163, 1997.r 1997 Wiley-Liss, Inc.Breast cancer is the most common neoplasm in women in developed countries, though its rates vary considerably across different populations (Harris et al., 1992;Ewertz and Duffy, 1994;Levi et al., 1994;Lipworth, 1995). A role of several hormonal factors in terms of relative risks has been consistently reported (Henderson, 1993;Kelsey et al., 1993;Lipworth, 1995), and although the strength of the associations for each risk factor or their combinations is not very elevated, their variation may well at least partly explain the national differences in breast cancer incidence and mortality (La Vecchia and Pampallona, 1986;Harris et al., 1992).Since attributable risks (AR) are a function of both odds ratios (OR) and prevalence of risk factors in the population, they tend to vary in different countries (Harris et al., 1992). A prospective study of the American Cancer Society (ACS) (Seidman et al., 1982) found that 21% of cancers diagnosed at ages 30-54 years and 29% of those diagnosed at ages 55-84 years could be attributed to one or more selected risk factors simply divided as ''low'' and ''high'' risk. An American case-c...

Flavonoids and Breast Cancer Risk in Italy

“…The well recognized risk factors for breast cancer (including age at menarche, age at menopause, parity, family history, alcohol drinking, body mass index, etc.) were consistently observed in the present data (47,48). Among the strengths of this study are the uniquely large dataset, the high intake of fruit and vegetables in the population, the satisfactory reproducibility and validity of the food frequency questionnaire (34,35), and the ability to control for total energy intake and major potential confounding factors.…”

Modulatory effects of neonatal exposure to TCDD, or a mixture of PCBs, p,p'-DDT, and p-p'-DDE, on methylnitrosourea-induced mammary tumor development in the rat.

“…d Analyzed concentrations indicate the actual congener concentrations in the 1,000× dosing solution, measured in a blind test by Wellington Laboratories (Guelph, Ontario, Canada). e Amounts given to the neonates when gavaged with 5.18 mL/kg of the 1,000× mixture at day 1 (a cumulative dose equal to 1,000 times human baby intake at day 0, 1, 2, 3, 4), day 5 (a cumulative dose for day 5,6,7,8,9), day 10 (a cumulative dose for day 10,11,12,13,14), day 15 (a cumulative dose for day 15,16,17,18,19), and day 20 of age (a cumulative dose for day 20,21,22,23,24). f PCB congeners are separated according to the position of the chlorine substitution.…”

“…The acknowledged risk factors for breast cancer are genetic predispositions (3)(4)(5)(6) and reproductive factors (7,8). These risk factors account for only 30-50% of the cases (5,(9)(10)(11)(12); thus, environmental factors (exposure to manmade and natural chemicals, dietary habits, lifestyle) are hypothesized to account for the remaining cases.…”

Some Hormonal Contraceptives, Hormone-Related Reproductive Breast Cancer Risk Factors Among Women in Port Harcourt: A Case-Control Study.

“…Age at first full-term pregnancy has been considered important to the risk of developing breast cancer by previous studies (Tavani et al, 1997;Kuru et al, 2002). In this study, the odds of developing breast cancer were found to be 0.39 times among women less than 18 years old at first pregnancy.…”

“…Hence, women with two or more deliveries were less likely to develop breast cancer compared to women who never has any delivery, although, the relationship was not statistically significant (P>0.005). Similarly, Tavani et al (1997) and Ebrahimi et al (2002) reported that breast cancer risk decreases with high parity. However, some studies of meta-analysis in Nordic countries and study conducted in Nigeria (Ewertz et al, 1990; Adebamowo and Adekunle, 1999), reported that no association was reported between risk of developing breast cancer and number of past deliveries among women studied.…”