A Case-Control Study on Breast Cancer Risk Factors in a Southern European Population

Abstract

A case-control study has been carried out among women attending a screening service in Palermo (Sicily) from 1974 through 1983 to ascertain the distribution of the most frequently investigated risk factors for breast cancer in a southern European population. Information has been obtained from the archives of the screening service. The analysis was separately conducted for pre- and post-menopausal cases and non-cases. Risk factors for pre-menopausal women are: nulliparity (nulliparous versus parous: OR 2.17, 95% CI 1.41-3.32); age at first birth (25-29 versus less than 20: OR 2.16, 95% CI 1.17-4.00); interval between menarche and first birth (greater than 20 years versus less than 6: OR 5.34, 95% CI 2.08-13.66); number of births (greater than 4 versus 1-2: OR 1.98, 95% CI 1.10-3.50). Risk factors for post-menopausal women are: nulliparity (nulliparous versus parous: OR 2.18, 95% CI 1.59-2.99); age at first birth (greater than 29 versus less than 20: OR 1.84, 95% CI 1.13-2.99); interval between menarche and first birth (16-20 years versus less than 6: OR 2.15, 95% CI 1.20-3.85). Age at menarche, age at menopause, breast feeding and family history were not found to be risk factors for breast cancer in the investigated population. The existence of influencing differences between northern and southern populations has been postulated.

Absence of association between reproductive variables and the risk of breast cancer in young women in Sweden and Norway

“…Our data did not support either the hypothesis of a cross-over effect of parity (Janerich & Hoff, 1982;Pathak et al, 1986;Negri et al, 1988) -with increased relative risks at younger ages and a protective effect in older women -or the finding of a rising risk with increasing number of births in premenopausal women (Brignone et al, 1987). Moreover, recent claims that induced abortions (Pike et al, 1981;Hadjimichael et al, 1986;Ewertz & Duffy, 1988), a long interval between menarche and first birth (Brignone et al, 1987), and a last pregnancy at a high age (La Vecchia et al, 1987) entail an increased risk was given no support. The absence of an association between abortions and breast cancer in this investigation is thus in accordance with results recently reported by others (Vessey et al, 1982;Brinton et al, 1983;Helmrich et al, 1983;La Vecchia et al, 1987;Rosenberg et al, 1988).…”

“…The results of several studies have pointed to interactions between parity and age (Janerich & Hoff, 1982;Pathak et al, 1986;Negri et al, 1988) or differences between the risk factors operative in pre-and postmenopausal women (Paffenbarger et al, 1980;Helmrich et al, 1983;Lipnick et al, 1984;Byers et al, 1985;McTierman & Thomas, 1986;Brignone et al, 1987;Layde et al, 1989). But there is no agreement as to the details.…”

Age at first full-term pregnancy, lactation and parity and risk of breast cancer: A case-control study in Spain

“…Previous studies have found a protective effect of lactation on breast cancer [3,13,18,24], however in our study lactation was not related to breast cancer risk while findings by MacMahon et al [14] and Brignone et al [2].…”

A case-control study of lactation and cancer of the breast

“…However, a small protective effect of breastfeeding among premenopausal parous women could be discerned. (Kalache et al, 1980;MacMahon et al, 1982;Brinton et al, 1983;Duffy et al, 1983;Brignone et al, 1987;London et al, 1990), as well as the only prospective study to date (Kvale and Heuch, 1987), has failed to establish an association between breastfeeding and breast cancer risk. London et al (1990), through retrospective assessment of lactation in the Nurses' Health Study, reported that in comparison to never breastfeeding, the relative risk was 0.95 for less than 7 months lactation, 0.87 for 7-11 months, 0.94 for 12-23 months and 0.98 for 24 months or longer.…”