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BACKGROUND: Mammographic density (MD), expressed as percentage of fibroglandular breast tissue, is an important risk factor for breast cancer. Our objective is to investigate the relationship between MD and residential proximity to pollutant industries in premenopausal Spanish women. METHODS: A cross-sectional study was carried out in a sample of 1225 women extracted from the DDM-Madrid study. Multiple linear regression models were used to assess the association of MD percentage (and their 95% confidence intervals (95%CIs)) and proximity (between 1 km and 3 km) to industries included in the European Pollutant Release and Transfer Register. RESULTS: Although no association was found between MD and distance to all industries as a whole, several industrial sectors showed significant association for some distances: "surface treatment of metals and plastic" (ß = 4.98, 95%CI = (0.85; 9.12) at =1.5 km, and ß = 3.00, 95%CI = (0.26; 5.73) at =2.5 km), "organic chemical industry" (ß = 6.73, 95%CI = (0.50; 12.97) at =1.5 km), "pharmaceutical products" (ß = 4.14, 95%CI = (0.58; 7.70) at =2 km; ß = 3.55, 95%CI = (0.49; 6.60) at =2.5 km; and ß = 3.11, 95%CI = (0.20; 6.01) at =3 km), and "urban waste-water treatment plants" (ß = 8.06, 95%CI = (0.82; 15.30) at =1 km; ß = 5.28; 95%CI = (0.49; 10.06) at =1.5 km; ß = 4.30, 95%CI = (0.03; 8.57) at =2 km; ß = 5.26, 95%CI = (1.83; 8.68) at =2.5 km; and ß = 3.19, 95%CI = (0.46; 5.92) at =3 km). Moreover, significant increased MD was observed in women close to industries releasing specific pollutants: ammonia (ß = 4.55, 95%CI = (0.26; 8.83) at =1.5 km; and ß = 3.81, 95%CI = (0.49; 7.14) at =2 km), dichloromethane (ß = 3.86, 95%CI = (0.00; 7.71) at =2 km), ethylbenzene (ß = 8.96, 95%CI = (0.57; 17.35) at =3 km), and phenols (ß = 2.60, 95%CI = (0.21; 5.00) at =2.5 km). CONCLUSIONS: Our results suggest no statistically significant relationship between MD and proximity to industries as a whole, although we detected associations with various industrial sectors and some specific pollutants, which suggests that MD could have a mediating role in breast carcinogenesis.

Experimental evidence indicates that exercise performed at different times of the day may affect circadian rhythms and circadian disruption has been linked to breast and prostate cancer. We examined in a population-based case-control study (MCC-Spain) if the time-of-day when physical activity is done affects prostate and breast cancer risk. Lifetime recreational and household physical activity was assessed by in-person interviews. Information on time-of-day of activity (assessed approximately 3 years after the assessment of lifetime physical activity and confounders) was available for 781 breast cancer cases, 865 population female controls, 504 prostate cases and 645 population male controls from 10 Spanish regions, 2008-2013. We estimated odds ratios (ORs) and 95% confidence intervals (95% CI) for different activity timings compared to inactive subjects using unconditional logistic regression adjusting for confounders. Early morning (8-10am) activity was associated with a protective effect compared to no physical activity for both breast (OR = 0.74, 95% CI = 0.48-1.15) and prostate cancer (OR = 0.73, 95% CI = 0.44-1.20); meta-OR for the two cancers combined 0.74 (95%CI = 0.53-1.02). There was no effect observed for breast or prostate cancer for late morning to afternoon activity while a protective effect was also observed for evening activity only for prostate cancer (OR = 0.75, 95% CI = 0.45-1.24). Protective effects of early morning activity were more pronounced for intermediate/evening chronotypes for both cancers. This is the first population-based investigation identifying a differential effect of timing of physical activity on cancer risk with more pronounced effects for morning hour activity. Our results, if confirmed, may improve current physical activity recommendations for cancer prevention.

Background: Gastric cancer is the fifth most frequent tumor worldwide. In Spain, it presents a large geographic variability in incidence, suggesting a possible role of environmental factors in its etiology. Therefore, epidemiologic research focused on environmental exposures is necessary. Objectives: To assess the association between risk of gastric cancer (by histological type and tumor site) and residential proximity to industrial installations, according to categories of industrial groups and specific pollutants released, in the context of a population-based multicase-control study of incident cancer conducted in Spain (MCC-Spain). Methods: In this study, 2664 controls and 137 gastric cancer cases from 9 provinces, frequency matched by province of residence, age, and sex were included. Distances from the individuals' residences to the 106 industries located in the study areas were computed. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95%CIs) for categories of distance (from 1 km to 3 km) to industries, adjusting for matching variables and potential confounders. Results: Overall, no excess risk of gastric cancer was observed in people living close to the industrial installations, with ORs ranging from 0.73 (at

Background Some studies have reported an inverse association between type 2 diabetes mellitus (T2DM) and prostate cancer (PCa), but results on this issue are still inconsistent. In this study, we evaluate whether this heterogeneity might be related to differences in this relationship by tumour or by individual genetic susceptibility to PCa. Methods We studied 1047 incident PCa cases and 1379 randomly selected controls, recruited in 7 Spanish provinces for the population-based MCC-Spain case-control. Tumour were classified by aggressiveness according to the International Society of Urological Pathology (ISUP), and we constructed a PCa polygenic risk score (PRS) as proxy for genetic susceptibility. The epidemiological questionnaire collected detailed self-reported data on T2DM diagnosis and treatment. The association between T2DM status and PCa was studied by fitting mixed logistic regression models, and, for its association by aggressiveness of PCa, with multinomial logistic regression models. To evaluate the possible modulator role of PRS in this relationship, we included the corresponding interaction term in the model, and repeated the analysis stratified by PRS tertiles. Results Globally, our results showed an inverse association between T2DM and overall PCa limited to grade 1 tumours (ORISUP = 1: 0.72; 95% CI: 0.53-0.98), which could be compatible with a detection bias. However, PCa risk also varied with duration of diabetes treatment -inversely to metformin and positively with insulin-, without differences by aggressiveness. When we considered genetic susceptibility, T2DM was more strongly associated with lower PCa risk in those with lower PRS (ORtertile 1: 0.31; 95% CI: 0.11-0.87), independently of ISUP grade. Conclusions Our findings reinforce the need to include aggressiveness and susceptibility of PCa, and T2DM treatments in the study of the relationship between both diseases.

Background: The role of fatty acids (FAs) on mammographic density (MD) is unclear, and available studies are based on self-reported dietary intake. Objectives: This study assessed the association between specific serum phospholipid fatty acids (PLFAs) and MD in premenopausal women. Methods: The cross-sectional study DDM-Madrid recruited 1392 Spanish premenopausal women, aged 39-50 y, who attended a screening in a breast radiodiagnosis unit of Madrid City Council. Women completed lifestyle questionnaires and FFQs. Percentage MD was estimated using a validated computer tool (DM-Scan), and serum PLFA percentages were measured by GC-MS. Multivariable linear regression models were used to quantify the association of FA tertiles with MD. Models were adjusted for age, education, BMI, waist circumference, parity, oral contraceptive use, previous breast biopsies, and energy intake, and they were corrected for multiple testing. Results: Women in the third tertile of SFAs showed significantly higher MD compared with those in the first tertile (beta(T3vsT1) = 7.53; 95% CI: 5.44, 9.61). Elevated relative concentrations of palmitoleic (beta(T3vsT1) = 3.12; 95% CI: 0.99, 5.25) and gondoic (beta(T3vsT1) = 2.67; 95% CI: 0.57, 4.77) MUFAs, as well as high relative concentrations of palmitelaidic (beta(T3vsT1) = 5.22; 95% CI: 3.15, 7.29) and elaidic (beta(T3vsT1) = 2.69; 95% CI: 0.59, 4.79) trans FAs, were also associated with higher MD. On the contrary, women with elevated relative concentrations of n-6 (omega-6) linoleic (beta(T3vsT1) = -5.49; 95% CI; -7.62, -3.35) and arachidonic (beta(T3vsT1) = -4.68; 95% CI: -6.79, -2.58) PUFAs showed lower MD. Regarding desaturation indices, an elevated palmitoleic to palmitic ratio and a low ratio of oleic to steric and arachidonic to dihomo. gamma-linolenic acids were associated with higher MD. Conclusions: Spanish premenopausal women with high relative concentrations of most SFAs and some MUFAs and trans FAs showed an increased MD, whereas those with high relative concentrations of some n-6 PUFAs presented lower density. These results, which should be confirmed in further studies, underscore the importance of analyzing serum FAs individually.

Modifying behavior towards healthier lifestyles could prevent a significant number of malignant tumors. We evaluated the prevalence of healthy habits against cancer in Spanish women free of this disease, taking as a reference the recommendations for cancer prevention included in the European Code Against Cancer (ECAC), and we explored the characteristics associated with it. Our population comprised 3,584 women recruited in a population-based cross-sectional study carried out in 7 breast cancer screening programs. Information was directly surveyed and used to calculate a score based on ECAC recommendations referred to bodyweight, physical activity, diet, breastfeeding, tobacco, alcohol and hormone replacement therapy use. The degree of adherence was estimated with a score that evaluated null (0 points), partial (0.5 points) and full adherence (1 point) of each specific recommendation. Associations were explored using binary and ordinal logistic regression models. The median score was 5.7 out of 9 points. Recommendations with lower adherence were those related to intake of red/processed meat and foods high in salt (23% of total adherence), physical activity (24%) and body weight (29%), and recommendations with greater adherence where those related to hormone replacement therapy use (91%), vegetable intake (84%), alcohol (83%) and tobacco (61%). Overall adherence was better among older women, parous women, and in those living in rural areas, and worse among women with higher caloric intake. These recommendations should be evaluated periodically. Screening programs can be an appropriate place to disseminate this information.

Purpose: We explored the association of the previously described Western, prudent and Mediterranean dietary patterns with prostate cancer risk by tumor aggressiveness and extension. Materials and Methods: MCC-Spain (Multicase-Control Study on Common Tumors in Spain) is a population based, multicase-control study that was done in 7 Spanish provinces between September 2008 and December 2013. It collected anthropometric, epidemiological and dietary information on 754 histologically confirmed incident cases of prostate cancer and 1,277 controls 38 to 85 years old. Three previously identified dietary patterns, including Western, prudent and Mediterranean, were reconstructed using MCC-Spain data. The association of each pattern with prostate cancer risk was assessed by logistic regression models with random, province specific intercepts. Risk according to tumor aggressiveness (Gleason score 6 vs greater than 6) and extension (cT1-cT2a vs cT2b-cT4) was evaluated by multinomial regression models. Results: High adherence to a Mediterranean dietary pattern rich not only in fruits and vegetables but also in fish, legumes and olive oil was specifically associated with a lower risk of Gleason score greater than 6 prostate cancer (quartile 3 vs 1 relative RR 0.66, 95% CI 0.46-0.96 and quartile 4 vs 1 relative RR 0.68, 95% CI 0.46-1.01, p-trend = 0.023) or with higher clinical stage (cT2b-T4 quartile 4 vs 1 relative RR 0.49, 95% CI 0.25-0.96, p-trend = 0.024). This association was not observed with the prudent pattern, which combines vegetables and fruits with low fat dairy products, whole grains and juices. The Western pattern did not show any association with prostate cancer risk. Conclusions: Nutritional recommendations for prostate cancer prevention should consider whole dietary patterns instead of individual foods. We found important differences between the Mediterranean dietary pattern, which was associated with a lower risk of aggressive prostate cancer, and Western and prudent dietary patterns, which had no relationship with prostate cancer risk.

Objectives The association between occupational exposures and mammographic density (MD), a marker of breast cancer risk, has not been previously explored. Our objective was to investigate the influence of occupational exposure to chemical, physical and microbiological agents on MD in adult women. Methods This is a population-based cross-sectional study based on 1476 female workers aged 45-65 years from seven Spanish breast cancer screening programmes. Occupational history was surveyed by trained staff. Exposure to occupational agents was assessed using the Spanish job-exposure matrix MatEmESp. Percentage of MD was measured by two radiologists using a semiautomatic computer tool. The association was estimated using mixed log-linear regression models adjusting for age, education, body mass index, menopausal status, parity, smoking, alcohol intake, type of mammography, family history of breast cancer and hormonal therapy use, and including screening centre and professional reader as random effects terms. Results Although no association was found with most of the agents, women occupationally exposed to perchloroethylene (e(beta)=1.51; 95% CI 1.04 to 2.19), ionising radiation (e(beta)=1.23; 95% CI 0.99 to 1.52) and mould spores (e(beta)=1.44; 95% CI 1.01 to 2.04) tended to have higher MD. The percentage of density increased 12% for every 5 years exposure to perchloroethylene or mould spores, 11% for every 5 years exposure to aliphatic/alicyclic hydrocarbon solvents and 3% for each 5 years exposure to ionising radiation. Conclusions Exposure to perchloroethylene, ionising radiation, mould spores or aliphatic/alicyclic hydrocarbon solvents in occupational settings could be associated with higher MD. Further studies are needed to clarify the accuracy and the reasons for these findings.

Breast cancer is the most frequent tumor in women worldwide, although well-established risk factors account for 53%-55% of cases. Therefore, other risk factors, including environmental exposures, may explain the remaining variation. Our objective was to assess the relationship between risk of breast cancer and residential proximity to industries, according to categories of industrial groups and specific pollutants released, in the context of a population-based multicase-control study of incident cancer carried out in Spain (MCC-Spain). Using the current residence of cases and controls, this study was restricted to small administrative divisions, including both breast cancer cases (452) and controls (1511) in the 10 geographical areas recruiting breast cancer cases. Distances were calculated from the respective woman's residences to the 116 industries located in the study area. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (95%CIs) for categories of distance (between 1 km and 3 km) to industrial plants, adjusting for matching variables and other confounders. Excess risk (OR; 95%CI) of breast cancer was found near industries overall (1.30; 1.00-1.69 at 3 km), particularly organic chemical industry (2.12; 1.20-3.76 at 2.5 km), food/beverage sector (1.87; 1.26-2.78 at 3 km), ceramic (4.71; 1.62-13.66 at 1.5 km), surface treatment with organic solvents (2.00; 1.23-3.24 at 3 km), and surface treatment of plastic and metals (1.51; 1.06-2.14 at 3 km). By pollutants, the excess risk (OR; 95% CI) was detected near industries releasing pesticides (2.09; 1.14-3.82 at 2 km), and dichloromethane (2.09; 1.28-3.40 at 3 km). Our results suggest a possible increased risk of breast cancer in women living near specific industrial plants and support the need for more detailed exposure assessment of certain agents released by these plants. (C) 2018 Elsevier Ltd. All rights reserved.

Objectives: Mammographic density (MD) is a strong risk factor for breast cancer. The present study evaluates the association between relative caloric intake and MD in Spanish women. Study design: We conducted a cross-sectional study in which 3517 women were recruited from seven breast cancer screening centers. MD was measured by an experienced radiologist using craniocaudal mammography and Boyd's semi-quantitative scale. Information was collected through an epidemiological survey. Predicted calories were calculated using linear regression models, including the basal metabolic rate and physical activity as explanatory variables. Overeating and caloric restriction were defined taking into account the 99% confidence interval of the predicted value. Odds ratios (OR) and 95% confidence intervals (95%CI) were estimated using center-specific mixed ordinal logistic regression models, adjusted for age, menopausal status, body mass index, parity, tobacco use, family history of breast cancer, previous biopsies, age at menarche and adherence to a Western diet. Main outcome measure: Mammographic density. Results: Those women with an excessive caloric intake ( > 40% above predicted) presented higher MD (OR = 1.41, 95%CI = 0.97-2.03; p = 0.070). For every 20% increase in relative caloric consumption the probability of having higher MD increased by 5% (OR = 1.05, 95%CI = 0.98-1.14; p = 0.178), not observing differences between the categories of explanatory variables. Caloric restriction was not associated with MD in our study. Conclusions: This is the first study exploring the association between MD and the effect of caloric deficit or excessive caloric consumption according to the energy requirements of each woman. Although caloric restriction does not seem to affect breast density, a caloric intake above predicted levels seems to increase this phenotype.

Objectives: The association between breast cancer (BC) and thyroid disorders has been widely explored with unclear results. Mammographic density (MD) is one of the strongest risk factor for BC. This study explores the relationship between thyroid diseases and MD in Spanish women. Materials & methods: This cross-sectional study covered 2883 women aged 47-71 years participating in 7 BC screening programs in 2010. They allowed access to their mammograms, had anthropometrical-measures taken, and answered a telephonic epidemiological interview which included specific questions on thyroid diseases. Percentage of MD was assessed with a semiautomatic-computer tool (DM-scan) by two trained radiologists. We calculated the geometric mean of MD percentages (mean MD). Multivariable mixed linear regression models with random screening-center-specific intercepts were fitted, using log-transformed percentage of MD as dependent variable and adjusting for age, body mass index, menopausal status and other confounders. e(beta) represents the relative increase of mean MD. Results: 13.9% of the participants reported personal history of thyroid disease. MD was not associated to hyperthyroidism (e(beta): 1.05, 95%CI: 0.82-1.36), hypothyroidism (e(beta):1.02, 95%CI: 0.75-1.38), thyroid nodules (e(beta):1.01, 95%CI: 0.85-1.19) or thyroid cancer (e(beta):1.03, 95%CI: 0.56-1.92). However, women with goiter had lower MD (mean MDno-goiter: 13.4% vs mean MDgoiter: 10.6%; e(beta):0.79, 95%CI: 0.64-0.98) and those with Hashimoto thyroiditis had higher MD (mean MDno-thyroiditis: 13.3% vs mean MDthyroidits: 25.8%; e(beta) 95%CI: 1.00-3.77). Conclusion: Functional thyroid disorders were not related to MD. However, MD was lower in women with goiter and higher in those reporting Hashimoto's thyroiditis. These relationships should be confirmed in future studies. (C) 2017 Elsevier Ltd. All rights reserved.

Background: Night-shift work (NSW) has been suggested as a possible cause of breast cancer, and its association with mammographic density (MD), one of the strongest risk factors for breast cancer, has been scarcely addressed. This study examined NSW and MD in Spanish women. Methods: The study covered 2,752 women aged 45-68 years recruited in 2007-2008 in 7 population-based public breast cancer screening centers, which included 243 women who had performed NSW for at least one year. Occupational data and information on potential confounders were collected by personal interview. Two trained radiologist estimated the percentage of MD assisted by a validated semiautomatic computer tool (DM-scan). Multivariable mixed linear regression models with random screening center-specific intercepts were fitted using log-transformed percentage of MD as the dependent variable and adjusting by known confounding variables. Results: Having ever worked in NSW was not associated with MD [e(beta):0.96; 95% confidence interval (CI), 0.86-1.06]. However, the adjusted geometric mean of the percentage of MD in women with NSW for more than 15 years was 25% higher than that of those without NSW history (MD>15 (years):20.7% vs. MDnever:16.5%; e(beta):1.25; 95% CI, 1.01-1.54). This association was mainly observed in postmenopausal participants (e(beta):1.28; 95% CI, 1.00-1.64). Among NSW-exposed women, those with

OBJECTIVE: To examine the association between two dietary patterns (Western and Mediterranean), previously linked to breast cancer risk, and mammographic density. METHODS: This cross-sectional study included 3,584 women attending population-based breast cancer screening programs and recruited between October 7, 2007, and July 14, 2008 (participation rate 74.5%). Collected data included anthropometric measurements; demographic, obstetric, and gynecologic characteristics; family and personal health history; and diet in the preceding year. Mammographic density was blindly assessed by a single radiologist and classified into four categories: less than 10%, 10-25%, 25-50%, and greater than 50%. The association between adherence to either a Western or a Mediterranean dietary pattern and mammographic density was explored using multivariable ordinal logistic regression models with random center-specific intercepts. Models were adjusted for age, body mass index, parity, menopause, smoking, family history, hormonal treatment, and calorie and alcohol intake. Differences according to women's characteristics were tested including interaction terms. RESULTS: Women with a higher adherence to the Western dietary pattern were more likely to have high mammographic density (n=242 [27%]) than women with low adherence (n=169 [19%]) with a fully adjusted odds ratio (ORQ4vsQ1) of 1.25 (95% confidence interval [CI] 1.03-1.52). This association was confined to over-weight-obese women (adjusted ORQ4vsQ1 [95% CI] 1.41 [1.13-1.76]). No association between Mediterranean dietary pattern and mammographic density was observed. CONCLUSION: The Western dietary pattern was associated with increased mammographic density among overweight-obese women. Our results might inform specific dietary recommendations for women with high mammographic density.

Background Diet is a key modifiable risk for many chronic diseases, but it remains unclear whether dietary patterns from one study sample are generalizable to other independent populations. Objective The primary objective of this study was to assess whether data-driven dietary patterns from one study sample are applicable to other populations. The secondary objective was to assess the validity of two criteria of pattern similarity. Methods Six dietary patterns-Western (n = 3), Mediterranean, Prudent, and Healthyfrom three published studies on breast cancer were reconstructed in a case-control study of 973 breast cancer patients and 973 controls. Three more internal patterns (Western, Prudent, and Mediterranean) were derived from this case-control study's own data. Statistical analysis Applicability was assessed by comparing the six reconstructed patterns with the three internal dietary patterns, using the congruence coefficient (CC) between pattern loadings. In cases where any pair met either of two commonly used criteria for declaring patterns similar (CC >= 0.85 or a statistically significant [P< 0.05] Pearson correlation), then the true similarity of those two dietary patterns was doublechecked by comparing their associations to risk for breast cancer, to assess whether those two criteria of similarity are actually reliable. Results Five of the six reconstructed dietary patterns showed high congruence (CC > 0.9) to their corresponding dietary pattern derived from the case-control study's data. Similar associations with risk for breast cancer were found in all pairs of dietary patterns that had high CC but not in all pairs of dietary patterns with statistically significant correlations. Conclusions Similar dietary patterns can be found in independent samples. The P value of a correlation coefficient is less reliable than the CC as a criterion for declaring two dietary patterns similar. This study shows that diet scores based on a particular study are generalizable to other populations.

Objective: The use of some forms of hormone therapy (HT) is associated with an increase in mammographic density-a major risk factor for breast cancer. The role of isoflavones, however, is unclear. Here, we quantify the prevalence of HT and isoflavone use among postmenopausal Spanish women, determine associated risk factors, and explore the relationship between these therapies and mammographic density. Methods: This cross-sectional study included 2,754 postmenopausal women who underwent breast cancer screening in seven geographical areas. Mammographic density was evaluated using Boyd's semiquantitative scale. Multinomial logistic regression models were adjusted to assess risk factors associated with both therapies. Ordinal regression models were fitted to study the association between HT and isoflavone consumption with mammographic density. Results: The prevalence of ever-use of HT was 12%, whereas that of the current use was 2.3%. Isoflavone lifetime prevalence was 3.7%, and current use was 1.7%. The most common HT types were tibolone and estrogens. Surgical menopause, oral contraceptive use, educational level, population density, and years since menopause were positively associated with HT, whereas body mass index and parity were inversely associated. Mammographic density was not associated with current or past HT use. However, women who reported having consumed isoflavones in the past and those who started their use after menopause had a higher mammographic density when compared with never-users (odds ratio 1.98, 95% CI 1.21-3.25, P = 0.007; and odds ratio 1.60, 95% CI 1.01-2.53, P = 0.045 respectively). Conclusions: Our results show a low prevalence of HT and isoflavone use in postmenopausal Spanish women. In this population, HT use was not associated with mammographic density, whereas some categories of isoflavone users had higher density.

High mammographic density (MD) is a phenotype risk marker for breast cancer. Body mass index (BMI) is inversely associated with MD, with the breast being a fat storage site. We investigated the influence of abdominal fat distribution and adult weight gain on MD, taking age, BMI and other confounders into account. Because visceral adiposity and BMI are associated with breast cancer only after menopause, differences in pre- and post-menopausal women were also explored. We recruited 3,584 women aged 45-68 years within the Spanish breast cancer screening network. Demographic, reproductive, family and personal history data were collected by purpose-trained staff, who measured current weight, height, waist and hip circumferences under the same protocol and with the same tools. MD was assessed in the left craniocaudal view using Boyd's Semiquantitative Scale. Association between waist-to-hip ratio, adult weight gain (difference between current weight and self-reported weight at 18 years) and MD was quantified by ordinal logistic regression, with random center-specific intercepts. Models were adjusted for age, BMI, breast size, time since menopause, parity, family history of breast cancer and hormonal replacement therapy use. Natural splines were used to describe the shape of the relationship between these two variables and MD. Waist-to-hip ratio was inversely associated with MD, and the effect was more pronounced in pre-menopausal (OR = 0.53 per 0.1 units; 95 % CI = 0.42-0.66) than in post-menopausal women (OR = 0.73; 95 % CI = 0.65-0.82) (P of heterogeneity = 0.010). In contrast, adult weight gain displayed a positive association with MD, which was similar in both groups (OR = 1.17 per 6 kg; 95 % CI = 1.11-1.23). Women who had gained more than 24 kg displayed higher MD (OR = 2.05; 95 % CI = 1.53-2.73). MD was also evaluated using Wolfe's and Tabar's classifications, with similar results being obtained. Once BMI, fat distribution and other confounders were considered, our results showed a clear dose-response gradient between the number of kg gained during adulthood and the proportion of dense tissue in the breast.

High mammographic density (MD) is used as a phenotype risk marker for developing breast cancer. During pregnancy and lactation the breast attains full development, with a cellular-proliferation followed by a lobular-differentiation stage. This study investigates the influence of obstetric factors on MD among pre- and post-menopausal women. We enrolled 3,574 women aged 45-68 years who were participating in breast cancer screening programmes in seven screening centers. To measure MD, blind anonymous readings were taken by an experienced radiologist, using craniocaudal mammography and Boyd's semiquantitative scale. Demographic and reproductive data were directly surveyed by purpose-trained staff at the date of screening. The association between MD and obstetric variables was quantified by ordinal logistic regression, with screening centre introduced as a random effect term. We adjusted for age, number of children and body mass index, and stratified by menopausal status. Parity was inversely associated with density, the probability of having high MD decreased by 16% for each new birth (P value < 0.001). Among parous women, a positive association was detected with duration of lactation [> 9 months: odds ratio (OR) = 1.33; 95% confidence interval (CI) = 1.02-1.72] and weight of first child (> 3,500 g: OR = 1.32; 95% CI = 1.12-1.54). Age at first birth showed a different effect in pre- and post-menopausal women (P value for interaction = 0.030). No association was found among pre-menopausal women. However, in post-menopausal women the probability of having high MD increased in women who had their first child after the age of 30 (OR = 1.53; 95% CI = 1.17-2.00). A higher risk associated with birth of twins was also mainly observed in post-menopausal women (OR = 2.02; 95% CI = 1.18-3.46). Our study shows a greater prevalence of high MD in mothers of advanced age at first birth, those who had twins, those who have breastfed for longer periods, and mothers whose first child had an elevated birth weight. These results suggest the influence of hormones and growth factors over the proliferative activity of the mammary gland.

Growth and development factors could contribute to the development of breast cancer associated with an increase in mammographic density. This study examines the influence of certain childhood-related, socio-demographic and anthropometric variables on mammographic density in adult woman. The study covered 3574 women aged 45-68 years, participating in breast cancer-screening programmes in seven Spanish cities. Based on a craniocaudal mammogram, blind, anonymous measurement of mammographic density was made by a single radiologist, using Boyd's semiquantitative scale. Data associated with the early stages of life were obtained from a direct survey. Ordinal logistic regression and generalised linear models were employed to estimate the association between mammographic density and the variables covered by the questionnaire. Screening programme was introduced as a random effects term. Age, number of children, body mass index (BMI) and other childhood-related variables were used as adjustment variables, and stratified by menopausal status. A total of 811 women (23%) presented mammographic density of over 50%, and 5% of densities exceeded 75%. Our results show a greater prevalence of high mammographic density in women with low prepubertal weight (OR: 1.18; 95% CI: 1.02-1.36); marked prepubertal height (OR: 1.25; 95% CI: 0.97-1.60) and advanced age of their mothers at their birth (> 39 years: OR: 1.28; 95% CI: 1.03-1.60); and a lower prevalence of high mammographic density in women with higher prepubertal weight, low birth weight and earlier menarche. The influence of these early-life factors may be explained by greater exposure to hormones and growth factors during the development of the breast gland, when breast tissue would be particularly susceptible to proliferative and carcinogenic stimulus.

Se estima que actualmente se diagnostican en España unos 162.000 casos de cáncer al año (sin contar el cáncer de piel no-melanoma) de los que 25.600 corresponden a carcinomas colorrectales, que es el tumor más frecuente de todos en términos absolutos. El siguiente tumor en frecuencia es el cáncer de pulmón con 18.800 casos nuevos, seguido del cáncer de mama en mujeres con 15.979 casos. Cuando se compara la incidencia de cáncer con la de los países de nuestro entorno, en hombres España presenta unas tasas ajustadas superiores a las del promedio de la UE, ocupando el 5º lugar. Sin embargo, en mujeres, España muestra las tasas de incidencia más bajas junto con Grecia. Para el cáncer de vejiga en hombres, España ocupa el primer lugar, con tasas bastante superiores a las del resto de países. Es importante constatar el incremento que está sufriendo la incidencia de cáncer en España y el contraste que supone frente a la evolución de la mortalidad. Para muchas localizaciones tumorales importantes (pulmón, estómago, vejiga), los registros poblacionales no cubren las provincias con una mayor mortalidad. It is estimated that at present in Spain around 162,000 cases of cancer are diagnosed each year (without including non-melanoma skin cancer), of which 25,600 correspond to colorectal carcinomas, which is the most frequent of all tumours in absolute terms. The next tumour in terms of frequency is lung cancer with 18,800 new cases, followed by breast cancer in women with 15,979 cases. When the incidence of cancer is compared with that in neighbouring countries, Spain shows adjusted rates in men higher than those of the average for the EU, occupying the 5th place. However, in women, Spain shows the lowest rates together with Greece. Spain occupies the first place for cancer of the bladder in men, with rates that are considerably higher than those of the rest of the countries. It is important to verify the increase underway in the incidence of cancer in Spain and the contrast that this represents facing the evolution of mortality. For many important tumoral localisations (lung, stomach, bladder), the population registers do not cover the provinces where there is a greater mortality.