On the age-dependent association between cancer of the breast and of the endometrium. A nationwide cohort study

Abstract

Summary The association between breast and endometrial cancer was investigated in a cohort consisting of 60,065 subjects (99% of all women in whom a first breast cancer was diagnosed in Sweden in 1960-63 and 1968-81 (Dunn, 1975;Cole & Cramer, 1977;Howe et al., 1984;Henderson et al., 1982;Willett & MacMahon, 1984). Descriptive epidemiologic studies have revealed high correlations between breast and endometrial cancer with regard to incidence and mortality rates. Such observations have been reported from international investigations in both low-and high-risk countries and in migrant populations (Dunn, 1975) and also from different parts of high-risk countries such as Canada (Howe et al., 1984) and the United States (Hoover et al., 1975;Winkelstein et al., 1977).The possibility that these demographic correlations reflect common genetic or environmental aetiologic factors has gained some support from cohort studies in which an increased risk of endometrial cancer has been found in breast cancer patients (Schoenberg et al., 1969) and vice versa (Schottenfeld & Berg, 1971;Bailar, 1963;MacMahon & Austin, 1969). The knowledge that can be derived from these analytic studies is generally uncertain, however, because of small numbers of cases, contradictory findings in blacks and whites (Newell et al., 1974), and limited information as to the possible dependence of an association between breast and endometrial cancer on age at diagnosis of the first primary (Bailar, 1963;MacMahon & Austin, 1969). The aim of this investigation was to confirm and extend in a larger cohort our recent finding that the association between breast and endometrial cancer is seemingly restricted to older women (Adami et al., 1984). The availability of a national cancer registry, reliable incidence figures for the studied population and opportunities for complete long-term follow-up facilitated our analysis. The overall frequency of underreporting has been shown to be -5% (Mattsson, 1977) and the completeness of registration of breast and endometrial cancer has been assessed from death certificates to be 98 and 95% respectively (Mattsson & Wallgren, 1984).The cohort was based on all women reported as having a first breast cancer diagnosed in 1960 through 1963 and 1968 through 1981. The four-year period of our previous study (Adami et al., 1984), 1964 through 1967, was excluded, since one major aim was to rule out the possibility that the excess risk previously found was due to chance (type I error) i.e. to a random high relative risk among the large number of tumour sites and subgroups that were analysed. Patients were included irrespective of whether they had had any other malignant disease reported prior to the breast cancer.A total of 61,341 women with breast cancer were notified to the Cancer Registry during the period of study. We excluded 583 women with an incomplete national registration number (a number which permits exclusive identification), precluding computerized linkages and followup in the Cancer Registry and other registers. The b...

Dietary inflammatory index and risk of epithelial ovarian cancer in African American women

“…It is unclear as to why a stronger association between the E‐DII and EOC risk was observed mainly among older women. It is possible that these findings are consistent with the observation that environmental or lifestyle factors, such as the E‐DII, may be stronger determinants of hormonally sensitive cancers diagnosed in older women compared to cancers diagnosed in younger women, which are more genetically determined . In addition, our findings may reflect a cumulative effect of consumption of pro‐inflammatory foods over the life‐course.…”

“…It is possible that these findings are consistent with the observation that environmental or lifestyle factors, such as the E-DII, may be stronger determinants of hormonally sensitive cancers diagnosed in older women compared to cancers diagnosed in younger women, which are more genetically determined. 41 In addition, our findings may reflect a cumulative effect of consumption of pro-inflammatory foods over the life-course. Another explanation could also be related to variations in insulin with aging as insulin resistance is associated with both older ages 42 and increases in inflammation.…”

Gynecologic effects of tamoxifen and the association with endometrial carcinoma

“…Among non-tamoxifen patients, breast cancer and endometrial cancer naturally share common risk factors, such as obesity and high endogenous estrogen levels [50,51]. A Swedish national study [52] documented that breast cancer patients had a relative risk (RR) of 1.72 of developing a uterine malignancy. Furthermore this risk was agedependent and rose to 2.4 if the patient was above 70 years of age.…”

Case Reports

“…The relationship between different hormone-dependent tumors and the implications of hormone therapy as treatment for breast cancer or for other reasons (tamoxifen, THS, gonadotropins, etc.) make gynecologic follow-up obligatory (2,19,20). This is also necessary because uterine metastases may develop in patients with breast cancer.…”