The Chernobyl accident resulted in a number of cases of thyroid cancer in females under the age of 20 y. Many of these individuals were treated with surgical removal of the thyroid gland followed by 131I ablation of residual thyroid tissue. Epidemiologic evidence demonstrates that 131I treatment for thyroid cancer or hyperthyroidism in adult women confers negligible risk of breast cancer. However, comparable data for younger women do not exist. Studies of external radiation exposure indicate that, for radiation exposures of as low as 0.2-0.7 Gy, the risk of breast cancer is greater for infant and adolescent female breast tissues than for adult female breast tissues. METHODS: The effective half-time of 131I measured in athyrotic patients was used together with the OLINDA/EXM computer code to estimate doses to breast tissue in 10-y-old, 15-y-old, and young adult females from ablation treatment. RESULTS: The dose to pediatric and young adult female breast tissue associated with a 5.6-GBq (150 mCi) ablation treatment may range from 0.35 to 0.55 Gy, resulting in a lifetime risk of breast cancer ranging from 2-4 cases per 100 such individuals exposed and a lifetime risk of solid tumors ranging from 8 to 17 solid tumors per 100 such individuals exposed. Administration of multiple ablation treatments, as often occurs with metastases, could result in doses ranging from 0.7 to 1 Gy, with corresponding increases in the lifetime cancer risk. CONCLUSION: These estimates suggest the need for additional research and a possible need for surveillance of young Chernobyl thyroid cancer patients who received 131I ablation treatment.
It has been suggested that abortions leave the breast epithelium in a proliferative state with an increased susceptibility to carcinogenesis. Results from previous studies of induced or spontaneous abortions and risk of subsequent breast cancer are contradictory, probably due to methodological considerations. We investigated the relationship between abortions and subsequent breast cancer risk in a case-control study using prospectively recorded exposure information. The study population comprised women recorded in the population-based Swedish Medical Birth Register between 1973-91. Cases were defined by linkage of the birth register to the Swedish Cancer Register and controls were randomly selected from the birth register. From the subjects' antenatal care records we abstracted prospectively collected information on induced and spontaneous abortions, as well as a number of potential confounding factors. Relative risk of breast cancer was estimated by odds ratios (OR) with 95% confidence intervals (95% CI). A reduced risk of breast cancer was observed for women with a history of at least 1 compared to no abortions (adjusted OR = 0.84, 95% CI = 0.72-0.99). The adjusted OR decreases step-wise with number of abortions to 0.59 (95% CI = 0.34-1.03) for 3 or more compared to no abortions. The patterns are similar for induced and spontaneous abortions. In conclusion, neither a history of induced nor spontaneous abortions is associated with an increased risk of breast cancer. Our data suggest a protective effect of pregnancies regardless of outcome.
Comment In: Int J Cancer. 2004 May 10;109(6):945-6; author reply 947-815027130
More than one-third of the calories consumed by U.S. and European populations contain acrylamide, a substance classified as a "probable human carcinogen" based on laboratory data. Thus, it is a public health concern to evaluate whether intake of acrylamide at levels found in the food supply is an important cancer risk factor. Mean dietary intake of acrylamide in adults averages 0.5 microg/kg of body weight per day, whereas intake is higher among children. Several epidemiological studies examining the relationship between dietary intake of acrylamide and cancers of the colon, rectum, kidney, bladder, and breast have been undertaken. These studies found no association between intake of specific foods containing acrylamide and risk of these cancers. Moreover, there was no relationship between estimated acrylamide intake in the diet and cancer risk. Results of this research are compared with other epidemiological studies, and the findings are examined in the context of data from animal models. The importance of epidemiological studies to establish the public health risk associated with acrylamide in food is discussed, as are the limitations and future directions of such studies.
Four authoritative reviews of active smoking and breast cancer have been published since 2000, but only one considered data after 2002 and conclusions varied. Three reviews of secondhand smoke (SHS) and breast cancer (2004-2006) each came to different conclusions. With 30 new studies since 2002, further review was deemed desirable. An Expert Panel was convened by four Canadian agencies, the Ontario Tobacco Research Unit, the Public Health Agency of Canada, Physicians for a Smoke-Free Canada and the Canadian Partnership Against Cancer to comprehensively examine the weight of evidence from epidemiological and toxicological studies and understanding of biological mechanisms regarding the relationship between tobacco smoke and breast cancer. This article summarises the panel's full report (http://www.otru.org/pdf/special/expert_panel_tobacco_breast_cancer.pdf). There are 20 known or suspected mammary carcinogens in tobacco smoke, and recognised biological mechanisms that explain how exposure to these carcinogens could lead to breast cancer. Results from the nine cohort studies reporting exposure metrics more detailed than ever/never and ex/current smoker show that early age of smoking commencement, higher pack-years and longer duration of smoking increase breast cancer risk 15% to 40%. Three meta-analyses report 35% to 50% increases in breast cancer risk for long-term smokers with N-acetyltransferase 2 gene (NAT2) slow acetylation genotypes. The active smoking evidence bolsters support for three meta-analyses that each reported about a 65% increase in premenopausal breast cancer risk among never smokers exposed to SHS. The Panel concluded that: 1) the association between active smoking and breast cancer is consistent with causality and 2) the association between SHS and breast cancer among younger, primarily premenopausal women who have never smoked is consistent with causality.
A healthy Nordic dietary pattern has shown beneficial effects in relation to several chronic diseases. However, no study has evaluated the association between a healthy Nordic food index (HNFI) and risk of breast cancer.
We conducted a prospective cohort study including 44,296 women, aged 29-49 at baseline in 1991-1992, who completed a food frequency questionnaire at baseline, and have been followed up ever since, through the Swedish Cancer Registry and Cause of Death Registry. Each woman was assigned a HNFI score ranging from 0 to 6. We calculated multivariable relative risks (RRs) and 95% confidence intervals (CIs) using Poisson regression models with attained age as the underlying timescale. The association between the HNFI and risk of breast cancer was assessed both overall, by menopausal status and by hormone receptor status.
A total of 1,464 breast cancer cases were diagnosed during a median follow-up time of 20 years. A higher adherence to the HNFI was not associated with a lower risk of breast cancer overall, nor of varied hormone receptor status, or when we examining premenopausal and postmenopausal women separately. The multivariable RRs (95% CI) for breast cancer per 1-point increment in the HNFI were 1.02 (95% CI 0.98-1.06) for all women, 1.01 (95% CI 0.95-1.08) for premenopausal women, and 1.02 (95% CI 0.97-1.07) for postmenopausal women.
Adherence to a HNFI was not associated with breast cancer incidence in this cohort of relatively young women, regardless of menopausal status or hormone receptor status.
The World Cancer Research Fund/American Association for Cancer Research (WCRF/AICR) has published eight nutrition-related recommendations for the prevention of cancer. However, few prospective studies have examined these recommendations by breast cancer hormone receptor subtype and only one case-control study has included the dietary supplements recommendation in their evaluation. We investigated whether adherence to the WCRF/AICR cancer prevention recommendations was associated with breast cancer incidence, overall and by hormone receptor subtype, in the Swedish Mammography Cohort. Among 31,514 primarily postmenopausal women diet and lifestyle factors were assessed with a self-administered food frequency questionnaire. A score was constructed based on adherence to the recommendations for body fatness, physical activity, energy density, plant foods, animal foods, alcoholic drinks and dietary supplements (score range 0-7). Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (95% CIs). During 15 years of follow-up 1,388 cases of breast cancer were identified. Women who met six to seven recommendations had a 51% decreased risk of breast cancer compared to women meeting only zero to two recommendations (95% CI = 0.35-0.70). The association between each additional recommendation met and breast cancer risk was strongest for the ER-positive/PR-positive subtype (HR = 0.86; 95% CI = 0.79-0.94), while for the ER-negative/PR-negative subtype the individual recommendations regarding plant and animal foods were most strongly associated with reduced risk. Our findings support that adherence to the WCRF/AICR recommendations reduces breast cancer risk in a population of primarily postmenopausal women. Promoting these recommendations to the public could help reduce breast cancer incidence.
OBJECTIVE: Exposure to environmental organochlorines has been examined as a potential risk factor for human breast cancer with mixed results. Our purpose was to examine associations between organochlorines and the development of breast cancer in a large prospective study using stored adipose tissue. METHODS: We conducted a nested case-control study of 409 postmenopausal women who developed breast cancer and 409 controls selected from the 29,875 women enrolled in the Danish Diet, Cancer, and Health cohort between 1993 and 1997. We measured concentrations of 14 pesticides and 18 polychlorinated biphenyls in adipose tissue, collected upon enrollment, and estimated relative risk (RR) of breast cancer using conditional logistic regression. RESULTS: The results showed no higher risk of breast cancer among women with higher levels of any pesticides or polychlorinated biphenyls; the RR associated with the upper quartile of 1,1-dichloro-2, 2-bis(p-chlorophenyl)ethylene concentration was 0.7 [95% confidence interval (95% CI), 0.5-1.2] contrasting the lower quartile, and for the sum of polychlorinated biphenyls the similar risk was 1.1 (95% CI, 0.7-1.7). We observed a pattern of substantially lower risk of estrogen receptor-negative breast cancer in association with higher levels of most of the pesticides and polychlorinated biphenyls; the RR for the higher quartile of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene was 0.1 (95% CI, 0.0-0.5) and for the sum of polychlorinated biphenyls it was 0.3 (95% CI, 0.1-0.9). CONCLUSION: The results do not support that higher organochlorine body levels increase the risk of breast cancer in postmenopausal women. The interpretation of the inverse association for estrogen receptor-negative breast cancer is currently unclear.
A longitudinal population study of 1462 women, aged 38-60 years, was carried out in Gothenburg, Sweden, in 1968-69. In univariate analysis anthropometric variables indicating centrally localized adipose tissue (waist circumference, the ratio of waist to hip circumference and the subscapular skinfold) showed significant age-standardized positive associations with the occurrence (prevalence + incidence data) of endometrial carcinoma. Incidence data suggested that measurements of centrally localized adipose tissue might be of predictive value for this malignancy as well as for ovarian carcinoma. In contrast, measurements of generalized obesity (body weight or body mass index) or peripherally localized adipose tissue (triceps skinfold) showed no associations to these malignancies. No relationship was observed between the anthropometric variables studied and breast carcinoma. The association observed between endometrial and ovarian carcinomas with central adipose tissue did, however, not remain in multivariate analysis when generalized obesity was taken into account. Centrally localized adipose tissue is known to be associated with endocrine abberations including irregular ovulation and menstruation, re-emphasizing the importance of endocrine factors for the pathogenesis of endometrial and ovarian carcinomas. No positive association was found between development of the carcinomas and initial measurements of blood glucose, serum lipids or blood pressure, found to be elevated in cross-sectional studies. An increase in these variables therefore probably are parallel phenomena rather than predictors. The women with endometrial or breast carcinomas smoked more than the remaining women. Although the number of end-points observed was limited these results suggest that measurements of adipose tissue distribution might be a valuable addition to the predictors of endometrial and ovarian carcinomas.(ABSTRACT TRUNCATED AT 250 WORDS)