Hereditary breast cancer in 19 females and 2 males: Kindred, P.G. 1940

Correlation between nutritional biomarkers and breast cancer: a case-control study

A case-control study to explore associations between retinoids, tocopherols, total and beta-carotenes and breast cancer was conducted by analysing concentrations of these biomarkers in adipose tissue, cheek cells and plasma. A total of 414 French-Canadians in Montreal with new diagnoses of breast cancer were age-matched to 429 population-based controls. Subjects were interviewed using a questionnaire, and biological samples from 287 cases and 112 controls were collected within 3 months of the diagnosis. Mean beta carotene concentrations in cheek cells were significantly lower among controls. Odds ratios (ORs) from logistic regression analysis were used to compare higher and lower tercile concentrations. Significant positive associations were observed in adipose tissue for retinoid [OR=2.11; 95% CI (1.09-4.08)] and beta carotene [OR=3.18; 95% CI (1.70-5.93)]; in cheek cells for beta carotene [OR=2.22; 95% CI (1.21-4.50)] and for total carotenes [OR=2.94; 95% CI (1.59-5.42)] and in plasma for beta carotene [OR=1.53; 95% CI (0.80-2.93)] and total carotenes [OR=1.04; 95% CI (0.53-2.05)]. Among the control groups, significant Pearson correlations were observed between cheek cells and adipose tissue for total carotenes (r=0.27; p=0.01) and cheek cells and plasma (r=0.22; p=0.04). In contrast to previous works, this study shows that high concentrations of retinoids and carotenes in adipose tissue and cheek cells are associated with increased risk of breast cancer. However, all these studies are limited by small sample size. Although our study tested a limited number of controls, important associations were observed. These results suggest that the effect of disease on biomarkers is fundamental to the interpretation of epidemiological data. We suggest either that the high levels of these biomarkers found in cancer patients in this study may be due to the disease process that affects the pharmacokinetics of the biomarker or that the disease causes a change in dietary habits. In addition, in studies involving the application of biomarkers to cancer epidemiology it is imperative that a typical biomarker concentration is not associated with breast cancer risk before further examination of the methodological limitations of epidemiological studies investigating this relationship. Therefore, sample size, selection bias, information bias, and confounding should be considered in the design of studies investigating the aetiological relationship between biomarkers and breast cancer.

Epidemiology of breast cancer among BRCA mutation carriers: an overview

Mutations in BRCA1 and BRCA2 have been associated with an increased lifetime risk of breast and ovarian cancers. Many of the well-recognized risk factors and risk modifiers in other women appear to operate similarly in BRCA mutation carriers. However, current evidence suggests that BRCA-related breast cancer risk is positively associated with pregnancy and parity, while smoking may reduce the risk. The incidence of BRCA1-related breast cancer is high before the age of 35 years and oral contraceptive use for 5 or more years is associated with increased risk of this disease among women carrying BRCA1 mutations.

Sociodemographic characteristics, smoking, medical and family history, and breast cancer

The relationship between sociodemographic characteristics, lifestyle, family history of cancer, medical history, and reproductive factors and breast cancer was investigated in a population-based case-control study of French Canadians in Montreal. In this study, a total of 414 French-Canadian cases and 429 age- and language-matched population controls were interviewed. Ever-married women showed significantly lower risk (OR: 0.64 [0.45-0.92]) for breast cancer, as did smokers (OR: 0.73 [0.55-0.98]), particularly of nonfilter cigarettes (OR: 0.36 [0.17-0.72]). Weight history, both for the year before the diagnosis of breast cancer and 10 years previously, was associated with risk for the disease. A strong inverse relationship was found between the number of full-term pregnancies (OR: 0.48 [0.28-0.82]) and the risk of breast cancer, while the p trend for late age at first pregnancy (p = 0.02) and menopause (p = 0.004) was statistically significant. A history of breast problems (OR: 1.87 [1.34-2.60]) and a history of breast cancer in relatives (OR: 2.95 [1.63-5.34]) were strongly associated with risk. This study confirms the risk factors of late age at first full-term pregnancy, nulliparity, late age at menopause, and positive family history of breast cancer in the etiology of this disease. Perhaps the protective effect of smoking against breast cancer could be due to its antiestrogenic influence.

A large multisite cancer family is linked to BRCA2

We identified a large French-Canadian family with 21 cases of breast cancer, including two affected brothers. Segregation of markers from chromosome 13q in this family showed linkage to the BRCA2 gene locus (lod = 3.67 at D13S289). A number of cancers of other types occurred in this family, including three cases of prostate cancer and two cases of lymphoma. The penetrance of breast cancer among BRCA2 carriers is estimated to be 75% to the age of 70.