Parity and risk of stomach cancer by sub-site: a national Swedish study

We investigated stomach cancer risk by anatomic sub-site in relation to parity, as a marker for higher exposure to sex hormones, in a case-control study, nested within a cohort of 2,406,439 Swedish women born in 1925 or later and followed from 1970 or age 30 until emigration, death, any cancer diagnosis, or through 2004, whichever occurred first. We identified 286 cardia and 2498 non-cardia stomach cancer cases with five matched controls for each case. Cross-linkage with the Multi-Generation Register provided information about reproductive history. Using conditional logistic regression models for estimating odds ratios (ORs) and corresponding 95% confidence intervals (CIs), adjusted for education level and occupation, we found no association between any aspect of parity and non-cardia stomach cancer (OR=1.01, 95% CI 0.89-1.15, comparing parous with nulliparous women). However, a 30% risk reduction for postmenopausal cardia cancer (OR=0.7, 95% CI 0.4-1.0) was noted among parous relative to nulliparous women and the risk for premenopausal cardia cancer fell with increasing number of children (P for trend=0.04). Our results indicate that exposure to female sex hormones does not protect against non-cardia stomach cancer and does not explain male predominance. The observed moderate inverse relationship between parity and cardia cancer may be mediated by non-hormonal factors and warrants further study.     

Perfluorinated alkylated substances serum concentration and breast cancer risk: Evidence from a nested case-control study in the French E3N cohort

Endocrine-disrupting chemicals are proposed to increase breast cancer (BC) incidence. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), two perfluorinated alkylated substances (PFASs), are suspected to be ubiquitously present in the blood of human population worldwide. We investigated the associations between serum concentrations of these substances and BC risk. Etude Epidémiologique auprès de femmes de l'Education Nationale is a cohort of 98,995 French women born in 1925–1950 and followed up since 1990. We sampled 194 BC cases and 194 controls from women with available blood samples. Serum concentrations of PFASs were measured by liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). Adjusted conditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). All statistical tests were two sided. While PFASs concentrations were not associated with BC risk overall, we found positively linear associations between PFOS concentrations and the risk of ER+ (3rd quartile: OR = 2.22 [CI = 1.05–4.69]; 4th quartile: OR = 2.33 [CI = 1.11–4.90]); P_trend = 0.04) and PR+ tumors (3rd quartile: OR = 2.47 [CI = 1.07–5.65]; 4th quartile: OR = 2.76 [CI = 1.21–6.30]; P_trend = 0.02). When considering receptor-negative tumors, only the 2nd quartile of PFOS was associated with risk (ER−: OR = 15.40 [CI = 1.84–129.19]; PR−: OR = 3.47 [CI = 1.29–9.15]). While there was no association between PFOA and receptor-positive BC risk, the 2nd quartile of PFOA was positively associated with the risk of receptor-negative tumors (ER−: OR = 7.73 [CI = 1.46–41.08]; PR−: OR = 3.44 [CI = 1.30–9.10]). PFAS circulating levels were differentially associated with BC risk. While PFOS concentration was linearly associated with receptor-positive tumors, only low concentrations of PFOS and PFOA were associated with receptor-negative tumors. Our findings highlight the importance of considering exposure to PFASs as a potential risk factor for BC.     

Plasma folate and risk of colorectal cancer in a nested case-control study: the Japan Public Health Center-based prospective study

Objective There is some evidence that folate may prevent colorectal cancer by stabilizing DNA sufficiently and methylating DNA appropriately. Plasma folate is a good marker to assess folate status in the body, but it has not been adequately examined in prospective epidemiologic studies. We investigated the association between plasma folate and the risk of colorectal cancer in a nested case-control study. Methods During a 11.5-year follow-up, 375 newly diagnosed colorectal cancers were identified in a cohort of 38,373 adults who had returned their baseline questionnaires and provided blood samples. Two controls for each case were selected from the cohort. The odds ratios (OR) and 95% confidence intervals (CI) of colorectal cancer for plasma folate was estimated using the conditional logistic regression model adjusted for potential confounding factors. Results Plasma folate was not associated with the risk of colorectal cancer in either men or women, although a small reduction of OR in men was observed in the second (OR, 0.70; 95% CI, 0.37–1.3), the third (OR, 0.72; 95% CI, 0.38–1.3), and the highest quartiles (OR, 0.86; 95% CI, 0.45–1.6) without a dose–response relationship (P for trend 0.88). A similar association was observed in the risk of colon or rectal cancer. No statistical interaction with the risk of colorectal cancer was observed between plasma folate and alcohol consumption. Conclusion Our results did not support the hypothesis that a folate-rich status may prevent colorectal cancer, though that finding may be due to an insufficient number of folate-deficient subjects in our study population.     

Thyroid cancer risk after thyroid examination with 131I: a population-based cohort study in Sweden

Ionizing radiation is the only established cause of thyroid cancer, though the effect of diagnostic administration of (131)I on thyroid cancer risk appears minimal. The annual number of thyroid examinations using radioiodine is currently 5 per 1,000 individuals worldwide, so this issue is of public health importance. Our objective was to evaluate the excess risk of thyroid cancer following a range of known doses of (131)I administered for diagnostic purposes. We conducted a nationwide, population-based cohort study in Sweden including all 36,792 individuals who received (131)I for diagnostic purposes during 1952-1969 and were alive and free of thyroid cancer 2 years after exposure. Accrual of person-time at risk commenced 2 years after the first (131)I administration. Follow-up for cancer was to the end of 1998. Standardized incidence ratios (SIRs) were calculated as the ratio between the observed and expected numbers of thyroid cancers. Estimates were stratified by previous exposure to external radiation therapy to the neck, reason for thyroid examination, (131)I dose, sex, age at exposure and time since exposure. Thyroid cancers (n = 129) were diagnosed during 886,618 person-years at risk. Excess thyroid cancers were observed only among the 1,767 patients who reported previous external radiation therapy to the neck [SIR = 9.8, 95% confidence interval (CI) 6.3-14.6] and among those originally referred due to suspicion of a thyroid tumor (SIR = 3.5, 95% CI 2.7-4.4 for 11,015 patients without previous external radiation therapy). The 24,010 patients without previous exposure to external radiation therapy to the neck who were referred for a reason other than suspicion of a thyroid tumor received an estimated dose to the thyroid of 0.94 Gy. Among these patients, 36 thyroid cancers were observed compared to 39.5 expected (SIR = 0.91, 95% CI 0.64-1.26). We found no evidence that administration of (131)I for diagnostic purposes increases risk of thyroid cancer. However, our study included few patients under age 20, so the results apply primarily to exposure among adults. Our data suggest that protraction of dose may result in a lower risk than brief X-ray exposure of the same total dose.     

Alcoholism and cancer risk: a population-based cohort study

The incidence of cancer was studied in a population-based cohort of 9,353 individuals (8,340 men and 1,013 women) with a discharge diagnosis of alcoholism in 1965–83, followed up for 19 years (mean 7.7). After exclusion of cancers in the first year of follow-up, 491 cancers were observed cf 343.2 expected through 1984 (standardized incidence ratio [SIR] = 1.4,95 percent confidence interval [CI] = 1.3–1.6). A similar excess risk of cancer was seen among men (SIR = 1.4, CI = 1.3–1.6) and among women (SIR = 1.5, CI = 1.1–2.0). We observed the established associations with cancers of the oral cavity and pharynx (SIR = 4.1, CI = 2.9–5.7), esophagus (SIR = 6.8, CI = 4.5–9.9), larynx (SIR = 3.3, CI = 1.7–6.0), and lung (SIR = 2.1, CI = 1.7–2.6), although confounding by smoking likely increased these risk estimates. While there was evidence of increased risk for pancreatic cancer (SIR = 1.5, CI = 0.9–2.3), alcoholism did not elevate the incidence of cancer of the stomach (SIR = 0.9, CI = 6–1.4), large bowel (SIR = 1.1, CI = 0.8–1.5), prostate (SIR = 1.0, CI = 0.8–1.3), urinary bladder (SIR = 1.0, CI = 0.6–1.5), or of malignant melanoma (SIR = 0.9, CI = 0.3–1.9). Among women, the number of breast cancers observed was close to expected (SIR = 1.2, CI = 0.6–2.2), although a significant excess number of cervical cancers occurred (SIR = 4.2, CI = 1.5–9.1). The results of this study, one of the first to evaluate the incidence of cancer in a population-based cohort of alcoholics of both sexes, are consistent with smaller previous studies, which were usually limited to cancer mortality and of short follow-up.Dr Adami is with the Cancer Epidemiology Unit, University Hospital, Uppsala, Sweden. Drs McLaughlin and Hsing are with the Biostatistics Branch, National Cancer Institute, Bethesda, MD, USA. Dr Wolk is with the Cancer Epidemiology Unit, University Hospital, Uppsala, Sweden. Dr Ekbom is with the Department of Surgery and with the Cancer Epidemiology Unit, University Hospital, Uppsala, Sweden. Dr Persson is with the Department of Obstetrics and Gynaecology and with the Cancer Epidemiology Unit, University Hospital, Uppsala, Sweden. Address correspondence to Dr Adami, Cancer Epidemiology Unit, University Hospital, S-751 85 Uppsala, Sweden. The work was performed at the Cancer Epidemiology Unit, Uppsala University, Sweden; the research was supported by grants from the Swedish Cancer Society.     

Radiotherapy did not increase thyroid cancer risk among women with breast cancer: A nationwide population‐based cohort study

The aim of this study was to evaluate whether an increased risk of thyroid cancer exists among women with breast cancer in Taiwan, particularly among those receiving RT. We used data from the National Health Insurance system of Taiwan for the investigation. The breast cancer cohort contained 55,318 women (including 28,187 who received RT and 27,131 who received no RT), each of whom was randomly frequency matched according to age and index year with three women without breast cancer from the general population. Cox's proportion hazards regression analysis was conducted to estimate the effects of breast cancer with or without RT treatment on subsequent thyroid cancer risk. We found that women with breast cancer exhibited a significantly higher risk of subsequent thyroid cancer (adjusted hazard ratio [aHR] = 1.98, 95% confidence interval [CI] = 1.60–2.44). The two groups (with or without RT) in the breast cancer cohort exhibited significantly increased risks. However, in the breast cancer cohort, the risk of thyroid cancer among women who received RT was not significantly higher than that of women who received no RT (aHR = 1.28, 95% CI = 0.90–1.83). Stratified analysis according to age revealed that only younger women with breast cancer (20–54 y) had a significantly higher risk of developing thyroid cancer. This study determined that Taiwanese women with breast cancer had a higher risk of developing thyroid cancer; however, RT seems to not play a crucial role in this possible relationship.     

Longchain serum fatty acids and risk of thyroid cancer: A population-based case-control study in Norway

Epidemiologic studies have shown an association between seafood consumption and risk of thyroid cancer. Fish meals increase the serum concentrations of the longchain fatty acids, eicosapentaenoic acid (205,n-3) (EPA) and docosahexaenoic acid (226,n-3) (DHA), for days. The hypothesis that serum concentrations of fatty acids may be associated with thyroid cancer risk therefore was tested in a population-based case-control study with 74 cases and 221 matched controls. Seventy-three cases with sera in the Norwegian serum bank (JANUS) were identified in the Norwegian Cancer Registry and matched with three controls, also in JANUS, on age, gender, place of residence, and time of blood sampling. Each case was matched with two controls. Serum concentrations of 11 longchain fatty acids were determined blindly by gas chromatography for all subjects. Controls were divided into three groups with increasing serum fatty acid concentrations, and odds ratios between cases and controls were estimated relative to the group with lowest serum level by univariate and multivariate analyses. The main finding was a significant inverse relation between the sum of arachidonic acid (204,n-6) (AA) and DHA serum concentrations and thyroid cancer risk. The significance of this association was weakened when the analyses were restricted to the papillary type of thyroid carcinoma. It was of the same order of magnitude whether the period between blood sampling and diagnosis was greater than eight years, or eight or less years. High EPA/AA ratio, indicating consumption of fish fat, was not associated significantly with increased thyroid-cancer risk. These data indicate that the association between seafood ingestion and increased thyroid-cancer risk may not be caused by the marine fatty acids.     

吸烟与原发性肝癌关系的巢式病例对照研究

目的 分析吸烟与上海市区中老年男性原发性肝癌的关系.方法 应用巢式病例对照研究方法,对一个18 244名男性队列随访11年,以队列中213例新发肝癌患者作为病例组,按照患者年龄、采样日期、同居住区等配对条件,从队列中随机抽取1094名健康人作为对照组.使用配对Logistic回归分析,调整可能的混杂因素,估计吸烟对肝癌发生的危险度和95%可信区间(CI).结果 调整肝炎、肝硬化、胆石症或其他胆囊病史及乙型肝炎病毒感染等可能的混杂因素后,男性吸烟者患肝痛的危险性是不吸烟者的1.91倍(95%CI为1.28～2.86),日随着每天吸烟量、吸烟年限和吸烟包年数的增加而增加.每天吸烟≥20支者、吸烟≥40年者和吸烟37包年者患肝癌的相对危险度分别为2.16(95%CI为1.37～3.40)、2.14(95%CI为1.18～3.87)和2.12(95%CI为1.21～3.74).吸烟开始年龄越小,危险性越大,吸烟开始年龄<20岁者患肝癌的危险性为2.57(95%CI为1.50～4.40).结论 吸烟是上海市区男性原发性肝癌的危险因素.     

Soluble Fas level and cancer mortality: findings from a nested case-control study within a large-scale prospective study

Soluble Fas (sFas) is known to play an important role in the development of cancers of various sites. To confirm whether or not the serum sFas level can be a predictor of cancer, we conducted a nested case-control study within a large-scale population-based cohort study in Japan. Serum samples were collected from 39,242 participants (13,839 men and 25,403 women) at baseline, all of whom were followed until 1997 for mortality and until 1994 for cancer incidence. Three controls were randomly selected and matched to each cancer case for gender, age and residential area. Serum values of sFas were measured by enzyme-linked immuno-adsorbent assay, using commercially available kits. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated using conditional logistic models, based on 798 total cancer mortality cases and their 2,353 matched controls. The risk of total cancer mortality was increased according to sFas levels, and the OR of the highest quartile compared with that of the lowest was 1.81 (95% CI; 1.40-2.34) after adjusting for smoking and drinking status, and body mass index. This positive association remained unaltered when cases were divided into 2 groups according to the observation period. Our results suggest that serum sFas has a possibility to detect people at high risk for cancer prior to diagnosis, since it increased before cancer diagnosis in those apparently healthy people.     

幽门螺杆菌感染与贲门癌发生风险的巢式病例对照研究

目的 探讨幽门螺杆菌(Hp)感染与贲门癌的关系.方法 采用非配比前瞻性巢式病例对照研究设计.1985年收集河南省林县研究队列(29 584人)的血液标本.随访至2001年,共诊断贲门癌1089例,从中随机抽取196例作为病例组.在能够代表整体人群的亚队列中,随机抽取185人作为对照组.用ELISA法检测血清标本中的Hp IgG抗体.计算Hp感染对贲门癌发生的总体OR值,并根据性别、采血时年龄和诊断时间分层,分析Hp感染对贲门癌发生的风险.结果 病例组与对照组Hp血清阳性率分别为82.1%和71.4%.Hp感染对贲门癌发生的总体OR为2.00(95%CI为1.21～3.31).在男性人群中,Hp感染OR为1.36,95%CI为0.71～2.60;女性人群中,Hp感染OR为4.19,95%CI为1.73～10.17.按照年龄进行分层分析显示,在≤50岁的人群中,Hp感染OR为3.45,95%CI为1.41～8.45;在51～60岁的人群中,Hp感染OR为1.56,95%CI为0.69～3.54;在>60岁的人群中,Hp感染OR为1.11,95%CI为0.37～3.33.按照诊断时间进行分层分析显示,在≤5年的人群中,Hp感染OR为1.78,95%CI为0.88～3.60;在6～10年的人群中,Hp感染OR为1.66,95%CI为0.80～3.44;在>10年的人群中,Hp感染OR为2.23,95%CI为1.05～4.74.结论 Hp感染增加河南省林县人群患贲门癌的风险,尤其在女性、年龄≤50岁、诊断时间>10年的人群中,Hp感染可使贲门癌发生的风险显著增加.     

Occupational magnetic field exposure and site-specific cancer incidence: a Swedish cohort study

Objective: Based on 1,596,959 men and 806,278 women, site-specific cancer incidence during 1971 through 1984 was analyzed in relation to occupational magnetic field exposure. The objective was to explore potential associations for cancer diseases beyond those extensively studied before (leukemia and brain tumors).Methods: Exposure was assessed from Census information on occupations that were linked to a job exposure matrix based on measurements. In a basic analysis, three levels of exposure were used. In addition, subjects with a more definite low exposure were compared with an aggregate of occupations with more definite exposures.Results: Observed associations were weak and there were no evident exposure–response relationships. For all cancer, an approximate 10% increase in risk was seen in the medium and high exposure groups. Several types of cancer were associated with exposure among men, including cancer of the colon, biliary passages and liver, larynx and lung, testis, kidney, urinary organs, malignant melanoma, non-melanoma skin cancer, astrocytoma III–IV. For women, associations were seen for cancer of the lung, breast, corpus uteri, malignant melanoma and chronic lymphocytic leukemia.Conclusions: In the analysis of occupations with a more definite exposure, the most notable finding for men was an increased risk of testicular cancer in young workers, and for women a clear association emerged for cancer of the corpus uteri. The outcome suggests an interaction with the endocrine/immune system.     

Diet and the risk of papillary and follicular thyroid carcinoma: a population-based case-control study in Sweden and Norway

A population-based case-control study was conducted in two regions ofSweden and Norway to investigate the association between dietary habits andthe risk of thyroid cancer. The consumption of selected foods was reported ina self-completed food-frequency questionnaire by 246 cases withhistologically confirmed papillary (n = 209) and follicular (n = 37) thyroidcarcinoma, and 440 age- and gender-matched controls. Odds ratios (OR) andtheir 95 percent confidence interval (CI) were calculated as estimates of therelative risk using conditional logistic regression. High consumption ofbutter (OR = 1.6, CI = 1.1-2.5) and cheese (OR = 1.5, CI = 1.0-2.4) wasassociated with increased risks. Residence in areas of endemic goiter inSweden was associated with an elevated risk, especially among women (OR =2.5, CI = 1.3-4.9). High consumption of cruciferous vegetables was associatedwith increased risk only in persons who ever lived in such areas. A decreasedrisk was associated with consumption of iodized salt in northern Norway, andwith use of iodized salt during adolescence among women (OR = 0.6, CI =0.6-1.0). The results of this study suggest a role of diet and environment inthe risk of thyroid cancer.     

Norwegian case-control study testing the hypothesis that seafood increases the risk of thyroid cancer

The hypothesis that consumption of seafood increases the risk of thyroid cancer has been tested by means of a matched case-control study. Linking the file of the National Health Screening Service (NHSS) containing dietary information about 60,000 Norwegians with the 1955–89 thyroid-cancer file of the Cancer Registry, by means of the 11-digit person-number, resulted in 92 cases—each of whom was matched with five controls with regard to age, gender, and place of residence. Forty-eight cases had answered questions on diet before diagnosis; 44 did so after diagnosis. Exposure data on seafood and seafood-related vitamins were recovered from the NHSS files for all 552 subjects. Odds ratios (OR) were computed by means of conditional logistic regression analysis. Univariate analysis of the 48 sets in which the case had answered the dietary questionnaire prior to the thyroid cancer diagnosis, as well as of all 92 sets, indicate that regular users of cod-liver oil, fish liver, or fish sandwich-spread run a higher risk of thyroid cancer than irregular and nonusers, and people eating more fish dinners per week also run a higher risk of thyroid cancer. Stepwise regression analysis corroborates the study hypothesis by showing that these two seafood variables increase the risk of thyroid cancer significantly. On the other hand, the results of a simultaneous regression analysis of these two seafood variables and a dietary vitamin-D index-variable tend to reduce the tenability of the above-mentioned conclusion since none of the OR estimates (all greater than one) reached significance in this part of the statistical analysis.Dr Glattre and Mr Haldorsen are with the Cancer Registry of Norway, Oslo, Norway. Dr Berg is with The Norwegian Radium Hospital, Oslo, Norway, and the Norwegian Cancer Society. Ms Stensvold is with the National Health Screening Service, Oslo, Norway. Ms Solvoll is with the Section for Dietary Research, University of Oslo, Norway. Correspondence should be addressed to Dr Glattre, Cancer Registry of Norway, Montebello, 0310 Oslo, Norway.     

Dietary factors and risk of prostate cancer: a case-control study in Ontario,Canada

The relationship between risk of prostate cancer and dietary intake of energy, fat, vitamin A, and other nutrients was investigated in a case-control study conducted in Ontario, Canada. Cases were men with a recent, histologically confirmed diagnosis of adenocarcinoma of the prostate notified to the Ontario Cancer Registry between April 1990 and April 1992. Controls were selected randomly from assessment lists maintained by the Ontario Ministry of Revenue, and were frequency-matched to the cases on age. The study included 207 cases (51.4 percent of those eligible) and 207 controls (39.4 percent of those eligible), and information on dietary intake was collected from them by means of a quantitative diet history. There was a positive association between energy intake and risk of prostate cancer, such that men at the uppermost quartile level of energy intake had a 75 percent increase in risk. In contrast, there was no clear association between the non-energy effects of total fat and monounsaturated fat intake and prostate cancer risk. There was some evidence for an inverse association with saturated fat intake, although the dose-response pattern was irregular. There was a weak (statistically nonsignificant) positive association between polyunsaturated fat intake and risk of prostate cancer. Relatively high levels of retinol intake were associated with reduced risk, but there was essentially no association between dietary -carotene intake and risk. There was no alteration in risk in association with dietary fiber, cholesterol, and vitamins C and E. Although these patterns were evident both overall and within age-strata, and persisted after adjustment for a number of potential confounding factors, they could reflect (in particular) the effect of nonrespondent bias.     

Parity and the risk of pancreatic cancer: A nested case-control study

Smoking is the only generally accepted risk factor for pancreatic cancer. Reproductive history has in recent studies been associated with pancreatic cancer, but with contradictory results. In order to evaluate a possible association between age at first birth and the number of births and pancreatic cancer, we conducted a nested case-control study by linking 2 Swedish nationwide registries: the Cancer Registry and The Fertility Registry. Among women born between 1925 and 1970, 1,015 patients with pancreatic cancer were compared with 5,073 age-matched controls. No association between pancreatic cancer and number of births was found. Age at first birth was inversely related with the risk of pancreatic cancer (OR per 5 years = 0.90; 95% CI 0.83<0R>–<0B>0.97; p<0B> = 0.01), an association mainly confined to women with a diagnosis of pancreatic cancer before 50 years of age (OR per 5 years = 0.85; 95% CI 0.73<0R>–<0B>1.00; p<0B> = 0.04). This trend remained after adjustment for parity, but was less prominent. Young age at first birth and high parity in Sweden are, however, associated with an increased frequency of smoking, thus at least some of the increased risk for pancreatic cancer in women with young age at first birth is likely to be explained by smoking acting as a confounder. Int. J. Cancer 77:224–227, 1998. © 1998 Wiley-Liss, Inc.     

Liver cancer risk, coffee, and hepatitis C virus infection: a nested case-control study in Japan

We examined hepatocellular carcinoma mortality in relation to coffee consumption and anti-hepatitis C virus (HCV) antibody seropositivity in a nested case-control study involving 96 cases. The multivariate-adjusted odds ratios (95% confidence interval) for daily coffee drinkers vs non-drinkers were 0.49 (0.25-0.96), 0.31 (0.11-0.85), and 0.75 (0.29-1.92) in all cases, in HCV-positive and in HCV-negative individuals, respectively.     

Dietary glycemic index and glycemic load, and breast cancer risk: A case-control study

Background:Certain types of carbohydrates increase glucoseand insulin levels to a greater extent than others. In turn, insulin mayraise levels of insulin-like growth factors, which may influence breastcancer risk. We analyzed the effect of type and amount of carbohydrateson breast cancer risk, using the glycemic index and the glycemic loadmeasures in a large case-control study conducted in Italy. Patients and methods:Cases were 2569 women with incident,histologically-confirmed breast cancer interviewed between 1991 and1994. Controls were 2588 women admitted to the same hospital network fora variety of acute, non-neoplastic conditions. Average daily glycemicindex and glycemic load were calculated from a validated 78-item foodfrequency questionnaire. Results:Direct associationswith breast cancer risk emerged for glycemic index (odds ratio, OR forhighest vs. lowest quintile = 1.4; Pfor trend <0.01) andglycemic load (OR = 1.3; P< 0.01). High glycemic indexfoods, such as white bread, increased the risk of breast cancer (OR= 1.3) while the intake of pasta, a medium glycemic index food, seemedto have no influence (OR = 1.0). Findings were consistent acrossdifferent strata of menopausal status, alcohol intake, and physicalactivity level. Conclusions:This study supports thehypothesis of moderate, direct associations between glycemic index orglycemic load and breast cancer risk and, consequently, a possible roleof hyperinsulinemia/insulin resistance in breast cancer development.     

Cholecystectomy,gallstones, tonsillectomy,and pancreatic cancer risk: a population-based case-control study in minnesota

Background:

Associations between medical conditions and pancreatic cancer risk are controversial and are thus evaluated in a study conducted during 1994–1998 in Minnesota.

Methods:

Cases (n=215) were ascertained from hospitals in the metropolitan area of the Twin Cities and the Mayo Clinic. Controls (n=676) were randomly selected from the general population and frequency matched to cases by age and sex. The history of medical conditions was gathered with a questionnaire during in-person interviews. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression.

Results:

After adjustment for confounders, subjects who had cholecystectomy or gallstones experienced a significantly higher risk of pancreatic cancer than those who did not (OR (95% CI): 2.11 (1.32–3.35) for cholecystectomy and 1.97 (1.23–3.12) for gallstones), whereas opposite results were observed for tonsillectomy (0.67 (0.48–0.94)). Increased risk associated with cholecystectomy was the greatest when it occurred ⩽2 years before the cancer diagnosis (5.93 (2.36–15.7)) but remained statistically significant when that interval was ⩾20 years (2.27 (1.16–4.32)).

Conclusions:

Cholecystectomy, gallstones, and tonsillectomy were associated with an altered risk of pancreatic cancer. Our study suggests that cholecystectomy increased risk but reverse causality may partially account for high risk associated with recent cholecystectomy.