Different menopausal hormone regimens and risk of breast cancer.

Background: There are considerable knowledge gaps concerning different estrogen and progestin formulations, regimens, and modes of administration of menopausal hormone therapy (HT) and the risk of breast cancer. Our objective was to assess the different treatment options for menopausal HT and the risk of breast cancer. Patients and methods: This Swedish prospective nationwide cohort study included all women who received ≥1 HT prescription during the study period 2005-2012 (290 186 ever-users), group-level matched (1 : 3) to 870 165 never-users; respectively, 6376 (2.2%) and 18 754 (2.2%) developed breast cancer. HT, ascertained from the Swedish Prescribed Drug Register, was subdivided by estrogen and progestogen formulation types, regimens (continuous versus sequential) and modes of administration (oral versus transdermal). The risk of invasive breast cancer was presented as adjusted odds ratios (OR) and 95% confidence intervals. Results: Current use of estrogen-only therapy was associated with a slight excess breast cancer risk [odds ratio (OR) = 1.08 (1.02-1.14)]. The risk for current estrogen plus progestogen therapy was higher [OR = 1.77 (1.69-1.85)] and increased with higher age at initiation [OR = 3.59 (3.30-3.91) in women 70+ years]. In contrast, past use was associated with reduced breast cancer risk. Current continuous estrogen/progestin use was associated with higher risk [OR = 2.18 (1.99-2.40) for progesterone-derived; OR = 2.66 (2.49-2.84) for testosterone-derived] than sequential use [OR = 1.37 (0.97-1.92) for progesterone-derived; OR = 1.12 (0.96-1.30) for testosterone-derived]. The OR for current use was 1.12 (1.04-1.20) for estradiol, 0.76 (0.69-0.84) for estriol, 4.47 (2.67-7.48) for conjugated estrogens, and 1.68 (1.51-1.87) for tibolone. Oral and cutaneous HT showed similar associations. Conclusion: Different HT regimens have profoundly different effects on breast cancer risk. Because of registry limitations some confounders could not be assessed. This knowledge may guide clinical decision-making when HT is considered.

Infectious mononucleosis and risk of breast cancer in a prospective study of women.

PURPOSE: The association between infectious mononucleosis (IM) and risk of breast cancer is unclear; no prospective studies have examined this relationship. We examined self-reported history and age at IM in relation to risk of invasive breast cancer. METHODS: Self-reported history and age at IM were examined in relation to risk of invasive breast cancer in a large cohort of women, the Nurses' Health Study II (81,807 women followed from 1989 to 2007). Through questionnaires, women were asked whether they ever had IM and if so, at what age. During follow-up, 2,349 cases of invasive breast cancer were documented. Cox proportional hazards regression was used to estimate relative risks (RR) and 95 % confidence intervals (CI) for the association of IM with breast cancer. RESULTS: The multivariable-adjusted RR for history of IM and risk of invasive breast cancer was 1.00 (95 % CI: 0.90-1.11). Similar null results were obtained when estrogen receptor/progesterone receptor positive and negative tumors were considered separately. There were no clear patterns of association between age at IM and risk of breast cancer: compared to women with no history of IM, those who were ≤15 years old when they had IM were at lower risk (RR: 0.77; 95 % CI: 0.60, 0.97), but there was no association for women who had IM at ages 16-19, 20-24, or 30+. However, an increased RR (1.45; 95 % CI: 1.02-2.04) was observed for women who had IM at ages 25-29. CONCLUSION: Results of this large prospective study do not support a clear association between history of clinical IM and risk of invasive breast cancer.

NeuroD2 and neuroD3: distinct expression patterns and transcriptional activation potentials within the neuroD gene family.

We have identified two new genes, neuroD2 and neuroD3, on the basis of their similarity to the neurogenic basic-helix-loop-helix (bHLH) gene neuroD. The predicted amino acid sequence of neuroD2 shows a high degree of homology to neuroD and MATH-2/NEX-1 in the bHLH region, whereas neuroD3 is a more distantly related family member. neuroD3 is expressed transiently during embryonic development, with the highest levels of expression between days 10 and 12. neuroD2 is initially expressed at embryonic day 11, with persistent expression in the adult nervous system. In situ and Northern (RNA) analyses demonstrate that different regions of the adult nervous system have different relative amounts of neuroD and neuroD2 RNA. Similar to neuroD, expression of neuroD2 in developing Xenopus laevis embryos results in ectopic neurogenesis, indicating that neuroD2 mediates neuronal differentiation. Transfection of vectors expressing neuroD and neuroD2 into P19 cells shows that both can activate expression through simple E-box-driven reporter constructs and can activate a reporter driven by the neuroD2 promoter region, but the GAP-43 promoter is preferentially activated by neuroD2. The noncongruent expression pattern and target gene specificity of these highly related neurogenic bHLH proteins make them candidates for conferring specific aspects of the neuronal phenotype.

Diet during pregnancy in relation to maternal weight gain and birth size.

OBJECTIVE: Maternal weight gain has been consistently linked to birth weight but, beyond maternal energy intake, no macronutrient has been associated with either of them. We have examined whether maternal energy-adjusted intake of macronutrients is associated with either maternal weight gain or birth-size parameters. DESIGN: Cohort study. SETTING: University hospital in Boston, USA. SUBJECTS: A total of 224 pregnant women coming for their first routine prenatal visit. The women were followed through delivery. INTERVENTIONS: None. Pregnant women's dietary intake during the second trimester was ascertained at the 27th week of pregnancy through a food frequency questionnaire. RESULTS: Intake of neither energy nor any of the energy-generating nutrients was significantly associated with birth size. In contrast, maternal weight gain by the end of the second trimester of pregnancy was significantly associated with energy intake (+0.9 kg/s.d. of intake; P approximately 0.006) as well as energy-adjusted intake of protein (+3.1 kg/s.d. of intake; P<10(-4)), lipids of animal origin (+2.6 kg/s.d. of intake; P<10(-4)) and carbohydrates (-5.2 kg/s.d. of intake; P<10(-4)). CONCLUSIONS: Although maternal weight gain is strongly associated with birth size, the indicated nutritional associations with weight gain are not reflected in similar associations with birth-size parameters. The pattern is reminiscent of the sequence linking diet to coronary heart disease (CHD) through cholesterol: diet has been conclusively linked to blood cholesterol levels and cholesterol levels are conclusively linked to this disease, even though the association of diet with CHD has been inconclusive and controversial.

The role of gene-environment interaction in the aetiology of human cancer: examples from cancers of the large bowel, lung and breast.

It has become increasingly clear that cancer can be considered neither purely genetic nor purely environmental. A relatively new area of cancer research has focused on the interaction between genes and environment in the same causal mechanism. Primary candidates for gene-environment interaction studies have been genes that encode enzymes involved in the metabolism of established cancer risk factors. There are common variant forms of these genes (polymorphisms), which may alter metabolism and increase or decrease exposure to carcinogens, thus impacting the risk of cancer. We present an overview of enzymes involved in carcinogen metabolism, present epidemiological tools to evaluate gene-environment interactions, and provide examples from cancers of the breast, lung and large bowel.

Prospects for chemoprevention of cancer.

The recent progress in molecular biology and pharmacology has increased the likelihood that cancer prevention will rely increasingly on interventions collectively termed 'chemoprevention'. Cancer chemoprevention is the use of agents to inhibit, delay or reverse carcinogenesis. A number of potential targets for chemoprevention have recently been identified. Many classes of agents including antioestrogens, anti-inflammatories, antioxidants and other diet-derived agents have shown a great deal of promise. In this review, we will begin by describing the general classes of chemopreventive agents and the mechanisms by which these agents act. We will then describe the opportunities that presently exist for chemoprevention of specific cancers.

NEUROD2 and NEUROD3 genes map to human chromosomes 17q12 and 5q23-q31 and mouse chromosomes 11 and 13, respectively.

NEUROD2 and NEUROD3 are transcription factors involved in neurogenesis that are related to the basic helix-loop-helix protein NEUROD. NEUROD2 maps to human chromosome 17q12 and mouse chromosome 11. NEUROD3 maps to human chromosome 5q23-q31 and mouse chromosome 13.