Carine Biessy

Body size and breast cancer risk: Findings from the European prospective investigation into cancer and nutrition (EPIC)

The evidence for anthropometric factors influencing breast cancer risk is accumulating, but uncertainties remain concerning the role of fat distribution and potential effect modifiers. We used data from 73,542 premenopausal and 103,344 postmenopausal women from 9 European countries, taking part in the EPIC study. RRs from Cox regression models were calculated, using measured height, weight, BMI and waist and hip circumferences; categorized by cohort‐wide quintiles; and expressed as continuous variables, adjusted for study center, age and other risk factors. During 4.7 years of follow‐up, 1,879 incident invasive breast cancers were identified. In postmenopausal women, current HRT modified the body size–breast cancer association. Among nonusers, weight, BMI and hip circumference were positively associated with breast cancer risk (all ptrend ≤ 0.002); obese women (BMI > 30) had a 31% excess risk compared to women with BMI < 25. Among HRT users, body measures were inversely but nonsignificantly associated with breast cancer. Excess breast cancer risk with HRT was particularly evident among lean women. Pooled RRs per height increment of 5 cm were 1.05 (95% CI 1.00–1.16) in premenopausal and 1.10 (95% CI 1.05–1.16) in postmenopausal women. Among premenopausal women, hip circumference was the only other measure significantly related to breast cancer (ptrend = 0.03), after accounting for BMI. In postmenopausal women not taking exogenous hormones, general obesity is a significant predictor of breast cancer, while abdominal fat assessed as waist–hip ratio or waist circumference was not related to excess risk when adjusted for BMI. Among premenopausal women, weight and BMI showed nonsignificant inverse associations with breast cancer.

Obesity and colon cancer: Does leptin provide a link?

Obesity, a risk factor for colorectal cancer, is associated with elevated serum levels of leptin, the adipocyte‐derived hormone, and insulin. Experimental and epidemiologic studies have indicated a role for insulin in the pathogenesis of colon cancer, and recent experimental studies have suggested a similar role for leptin. In a case‐control study nested in the Janus Biobank, Norway, we measured serum levels of leptin and C‐peptide (a marker of pancreatic insulin secretion) in cryopreserved prediagnostic sera from men (median age, 45 years) who were diagnosed with cancer of the colon (n = 235) or rectum (n = 143) after blood collection (median time, 17 years), and among 378 controls matched for age and date of blood collection. Conditional logistic regression analyses showed an approximately 3‐fold increase in colon cancer risk with increasing concentrations of leptin up to an odds ratio (OR) of 2.72 (95% CI = 1.44–5.12) for top vs. bottom quartile (ptrend = 0.008). The corresponding OR for C‐peptide was 1.81 (95% CI = 0.67–4.86; ptrend = 0.19). The risk estimates remained unchanged after mutual adjustment. No association of hormone levels with rectal cancer risk was found. Reproducibility of hormone measurements assessed by intraclass coefficients (ICCs) for paired samples taken 1 year apart was high for leptin (ICC = 0.82) but lower for C‐peptide (ICC = 0.30). Our results suggest that leptin is a risk factor for colon cancer, and that leptin may provide a link between obesity and colon cancer. Leptin may be directly involved in colon tumorigenesis or it may serve as a sensitive and robust marker of an obesity‐induced adverse endocrine environment. Only weak support for an association of insulin with colon cancer was found.

Validation and calibration of food-frequency questionnaire measurements in the Northern Sweden Health and Disease cohort.

OBJECTIVES To evaluate the reproducibility of, and to compare and calibrate, diet measures by the Northern Sweden 84-item food-frequency questionnaire (FFQ) with measures from 24-hour diet recalls (24-HDR). DESIGN Randomly selected respondents from the EPIC (diet-cancer) and MONICA (diet-cardiovascular disease) study cohort in Northern Sweden were invited to answer the FFQ twice over a one-year interval (FFQ1 and FFQ2), and to complete ten 24-hour recalls (reference method) in the months between. Plasma beta-carotene concentrations were determined from a subset of 47 participants. SETTING Västerbotten and Norrbotten, Northern Sweden. PARTICIPANTS Ninety-six men and 99 women, who completed the study. RESULTS The reproducibility of the FFQ was high in terms of both mean energy and nutrient intakes and relative ranking of participants by intake levels (median Pearson correlation of 0.68). Moderately higher food intake frequencies were recorded by FFQ1 compared with 24-hour recalls for dairy products, bread/cereals, vegetables, fruits and potato/rice/pasta, whereas meat, fish, sweet snacks and alcoholic beverage intakes were lower. The median Spearman coefficient of correlation between FFQ1 and the average of ten 24-HDR measurements was 0.50. Daily energy and nutrient intakes were similar for FFQ1 and 24-HDR measurements, except for fibre, vitamin C, beta-carotene and retinol (FFQ1>24-HDR) and sucrose and cholesterol Pearson coefficients of correlation between FFQ1 and 24-HDR corrected for attenuation due to residual day-to-day variation in the 24-HDR measurements ranged from 0.36 to 0.79 (median 0.54). Adjustment for energy had only very moderate effects on the correlation estimates. Calibration coefficients estimated by linear regression of the 24-HDR on the FFQ1 measurements varied between 0.30 and 0.59 for all nutrients except alcohol, which had calibration coefficients close to 1.0. These low calibration coefficients indicate that relative risk estimates corresponding to an absolute difference in dietary intake levels measured by the FFQ will generally be biased towards 1.0. Plasma beta-carotene levels had a Pearson coefficient of correlation of 0.47 with the 24-HDR measurements, and of 0.23 with FFQ1 measurements. CONCLUSIONS The Northern Sweden FFQ measurements have good reproducibility and an estimated level of validity similar to that of FFQ measurements in other prospective cohort studies. The results from this study will form the basis for the correction of attenuation and regression dilution biases in relative risk estimates, in future studies relating FFQ measurements to disease outcomes.

Prospective study of IGF-I, IGF-binding proteins, and breast cancer risk, in northern and southern Sweden.

Objective: To examine the possible relationships of breast cancer risk to prediagnostic plasma levels of insulin; insulin-like growth factor-I (IGF-I); and IGF-binding proteins -1, -2, and -3. Methods: Within two prospective cohorts in Umeå and Malmö we measured plasma concentrations of insulin, IGF-I, and IGFBPs for a total of 513 incident breast cancer cases and 987 matched controls. Results: Globally, risk was unassociated with levels of IGF-I, IGFBP-3, or IGF-I adjusted for IGFBP-3. When breaking down the analysis by subgroups of age at blood donation, an increase in risk was observed for increasing levels of IGF-I in women aged 55 or older, in the Umeå cohort only (odds ratios of 1.00, 1.73, 1.76, 1.90; ptrend = 0.05). This effect weakened, however, when the analysis was restricted to subjects who did not use exogenous hormones for the treatment of menopausal symptoms. Levels of IGF-I and IGFBP-3 were not related to risk in younger women, recruited before age 50, contrary to observations from previous studies. In a subcohort where blood samples had been collected after at least four hours of fasting, breast cancer risk showed no clear associations with levels of insulin, IGFBP-1, or IGFBP-2. Conclusions: Our results do not confirm earlier findings of an association of plasma IGF-I levels with breast cancer risk especially in young women, but suggest a possible association with postmenopausal breast cancer risk, possibly among ERT/HRT users only. Our results do not support the hypothesis that elevated plasma insulin levels, and reduced levels of IGFBP-1 and IGFBP-2, are associated with increased breast cancer risk.

Plasma insulin-like growth factor 1, insulin-like growth factor binding protein 3, and risk of colorectal cancer: a prospective study in northern Sweden

Background: Insulin-like growth factor 1 (IGF-1) has antiapoptotic and mitogenic effects on various cell types, and raised IGF-1 levels are increasingly being implicated as potential risk factors for cancer. Aims: To examine the relationship between IGF-1 and its major plasma binding protein, IGF binding protein 3 (IGFBP-3), and the risk of colorectal cancer. Methods: We conducted a case-control study nested within the Northern Sweden Health and Disease Cohort. IGF-1 and IGFBP-3 were measured in prediagnostic plasma samples from 168 men and women who developed cancers of the colon (n=110) or rectum (n=58), and from 336 matched controls. Results: Conditional logistic regression analyses showed an increase in colon cancer risk with increasing levels of IGF-1 (odds ratios (ORs) 1.00, 1.89, 2.30, 2.66; ptrend=0.03) and IGFBP-3 (ORs 1.00, 0.91, 1.80, 1.93; ptrend=0.02). Rectal cancer risk was inversely related to levels of IGF-1 (ORs 1.00, 0.45, 0.33, 0.33; ptrend=0.09) and IGFBP-3 (ORs 1.00, 0.75, 0.66, 0.49; ptrend=0.21). Mutual adjustments between IGF-1 and IGFBP-3 did not materially alter these relationships. Conclusions: These results support earlier findings of increased risk of colon cancer in subjects with elevated plasma IGF-1. Our results however do not support the hypothesis that the risk of rectal cancer could also be directly related to IGF-1 levels.

Circulating levels of sex steroid hormones and risk of endometrial cancer in postmenopausal women

Experimental and epidemiological data support a role for sex steroid hormones in the pathogenesis of endometrial cancer. The associations of pre‐diagnostic blood concentrations of estradiol, estrone, testosterone, androstenedione, DHEAS and SHBG with endometrial cancer risk were investigated. A case‐control study was nested within 3 cohorts in New York (USA), Umeå (Sweden) and Milan (Italy). Cases were 124 postmenopausal women with invasive endometrial cancer. For each case, 2 controls were selected, matching the case on cohort, age and date of recruitment. Only postmenopausal women who did not use exogenous hormones at the time of blood donation were included. Odds ratios (OR) and their 95% confidence intervals (CI) were estimated by conditional logistic regression. ORs (95% CI) for endometrial cancer for quartiles with the highest hormone levels, relative to the lowest were as follows: 4.13 (1.76–9.72), ptrend = 0.0008 for estradiol, 3.67 (1.71–7.88), ptrend = 0.0007 for estrone, 2.15 (1.05–4.40), ptrend = 0.04 for androstenedione, 1.74 (0.88–3.46), ptrend = 0.06 for testosterone, 2.90 (1.42–5.90), ptrend = 0.002 for DHEAS and 0.46 (0.20–1.05), ptrend = 0.01 for SHBG after adjustment for body mass index, use of oral contraceptives and hormone replacement therapy. The results of our multicenter prospective study showed a strong direct association of circulating estrogens, androgens and an inverse association of SHBG levels with endometrial cancer in postmenopausal women. The effect of elevated androstenedione and testosterone levels on disease risk seems to be mediated mainly through their conversion to estrogens, although an independent effect of androgens on tumor growth cannot be ruled out, in particular in the years close to diagnosis.

Serum levels of IGF-I, IGFBP-3 and colorectal cancer risk: results from the EPIC cohort, plus a meta-analysis of prospective studies.

Several prospective studies have shown a moderate positive association between increasing circulating insulin‐like growth factor‐I (IGF‐I) levels and colorectal cancer risk. However, the associations were often statistically nonsignificant, and the relationship of cancer risk with IGF‐Is major binding protein, IGFBP‐3, showed major discrepancies between studies. We investigated the association of colorectal cancer risk with serum IGF‐I, total and intact IGFBP‐3, in a case‐control study nested within the EPIC cohort (1,121 cases of colorectal cancer and 1,121 matched controls). Conditional logistic regression was used to adjust for possible confounders. Our present study results were combined in a meta‐analysis with those from 9 previous prospective studies to examine the overall evidence for a relationship of prediagnostic serum IGF‐I with colorectal cancer risk. In the EPIC study, serum concentrations of IGF‐I and IGFBP‐3 showed no associations with risk of colorectal cancer overall. Only in subgroup analyses did our study show moderate positive associations of IGF‐I levels with risk, either among younger participants only (and only for colon cancer) or among participants whose milk intakes were in the lowest tertile of the population distribution (RR for an increase of 100 ng/ml = 1.43 [95% CI = 1.13–1.93]). Nevertheless, in the meta‐analysis a modest positive association remained between serum IGF‐I and colorectal cancer risk overall (RR = 1.07 [1.01–1.14] for 1 standard deviation increase in IGF‐I). Overall, data from our present study and previous prospective studies combined indicate a relatively modest association of colorectal cancer risk with serum IGF‐I.

Plasma phospholipid fatty acid profiles and their association with food intakes: results from a cross-sectional study within the European Prospective Investigation into Cancer and Nutrition

BACKGROUND Plasma phospholipid fatty acids have been correlated with food intakes in populations with homogeneous dietary patterns. However, few data are available on populations with heterogeneous dietary patterns. OBJECTIVE The objective was to investigate whether plasma phospholipid fatty acids are suitable biomarkers of dietary intakes across populations involved in a large European multicenter study. DESIGN A cross-sectional study design nested to the European Prospective Investigation into Cancer and Nutrition (EPIC) was conducted to determine plasma fatty acid profiles in >3,000 subjects from 16 centers, who had also completed 24-h dietary recalls and dietary questionnaires. Plasma fatty acids were assessed by capillary gas chromatography. Ecological and individual correlations were calculated between fatty acids and select food groups. RESULTS The most important determinant of plasma fatty acids was region, which suggests that the variations across regions are largely due to different food intakes. Strong ecological correlations were observed between fish intake and long-chain n-3 polyunsaturated fatty acids (r = 0.78, P < 0.01), olive oil and oleic acid (r = 0.73, P < 0.01), and margarine and elaidic acid (r = 0.76, P < 0.01). Individual correlations varied across the regions, particularly between olive oil and oleic acid and between alcohol and the saturation index, as an indicator of stearoyl CoA desaturase activity. CONCLUSIONS These findings indicate that specific plasma phospholipid fatty acids are suitable biomarkers of some food intakes in the EPIC Study. Moreover, these findings suggest complex interactions between alcohol intake and fatty acid metabolism, which warrants further attention in epidemiologic studies relating dietary fatty acids to alcohol-related cancers and other chronic diseases.

Prediagnostic levels of C-peptide, IGF-I, IGFBP -1, -2 and -3 and risk of endometrial cancer†

Conditions related to chronic hyperinsulinemia, such as obesity, noninsulin dependent diabetes mellitus and polycystic ovary syndrome, are associated with an increased risk of endometrial cancer. Elevated plasma IGF‐I and decreased levels of IGF‐binding proteins have been shown to be associated with increased risk of several cancer types that are frequent in affluent societies. We investigated for the first time in a prospective study the association of pre‐diagnostic blood concentrations of C‐peptide (a marker of pancreatic insulin production), IGF‐I, IGFBP‐1, ‐2 and ‐3 with endometrial cancer risk. A case‐control study was nested within 3 cohorts in New York (USA), Umeå (Sweden) and Milan (Italy). It included 166 women with primary invasive endometrial cancer and 315 matched controls, of which 44 case and 78 control subjects were premenopausal at recruitment. Endometrial cancer risk increased with increasing levels of C‐peptide (ptrend = 0.0002), up to an odds ratio (OR) of 4.76 [95% confidence interval (CI) = 1.91–11.8] for the highest quintile. This association remained after adjustment for BMI and other confounders [OR for the top quintile = 4.40 (1.65–11.7)]. IGFBP‐1 levels were inversely related to endometrial cancer [ptrend = 0.002; OR in the upper quintile = 0.30 (0.15–0.62)], but the association was weakened and lost statistical significance after adjustment for confounders [ptrend = 0.06; OR in the upper quintile = 0.49 (0.22–1.07)]. Risk was unrelated to levels of IGF‐I, IGFBP‐2 and IGFBP‐3. Chronic hyperinsulinemia, as reflected by increased circulating C‐peptide, is associated with increased endometrial cancer risk. Decrease in the prevalence of chronic hyperinsulinemia, through changes in lifestyle or medication, is expected to prevent endometrial cancer.

Serum C-peptide, IGFBP-1 and IGFBP-2 and risk of colon and rectal cancers in the European Prospective Investigation into Cancer and Nutrition

Western style diets and lifestyles are associated with increasing rates of obesity, diabetes and insulin resistance. Higher circulating insulin levels may modulate cell proliferation and apoptosis either directly or indirectly by increasing the bioactivity of IGF‐I and decreasing the bioactivity of some of its binding proteins. The objective of this study was to determine the association of increasing levels of serum C‐peptide, a biomarker of pancreatic insulin secretion, and IGF binding proteins (IGFBP) ‐1 and ‐2 with colorectal cancer risk in a case–control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC), a large cohort involving 10 Western European countries. A total of 1,078 colorectal cancer cases were matched (age, date of blood donation, fasting status, gender, study center) to an equal number of control subjects. Relative cancer risks were estimated using conditional logistic regression models. Serum C‐peptide concentration was positively associated with an increased colorectal cancer risk for the highest versus the lowest quintile (OR = 1.56, 95% CI = 1.16–2.09, ptrend < 0.01), which was slightly attenuated after adjustment for BMI and physical activity (OR = 1.37, 95% CI = 1.00–1.88, ptrend = 0.10). When stratified by anatomical site, the cancer risk was stronger in the colon (OR = 1.67, 95% CI = 1.14–2.46, ptrend < 0.01) than in the rectum (OR = 1.42, 95% CI = 0.90–2.25, ptrend = 0.35). The cancer risk estimates were not heterogeneous by gender or fasting status. No clear colorectal cancer risk associations were observed for IGFBP‐1 or ‐2. This large prospective study confirms that hyperinsulinemia, as determined by C‐peptide levels, is associated with an increased colorectal cancer risk.