Apolipoproteins,lipids and risk of cancer

The epidemiological evidence for an obesity‐cancer association is solid, whereas the association between obesity‐associated lipoprotein levels and cancer is less evident. We investigated circulating levels of Apolipoprotein A1 (ApoA1), Apolipoprotein B (ApoB), LDL‐cholesterol (LDL‐C) and HDL‐cholesterol (HDL‐C) and association to risk of overall cancer and common cancer forms. The Malmö Diet and Cancer Study, a population‐based prospective cohort study, enrolled 17,035 women and 11,063 men (1991–1996). Incident cancer cases were ascertained by record linkage with the Swedish Cancer Registry until end of follow‐up, January 1, 2012. Baseline serum levels of ApoA1 and ApoB were analyzed for the entire cohort and HDL‐C and LDL‐C levels in 5,281 participants. Hazard ratios, with 95% confidence interval, were calculated using Cox's proportional hazards analysis. In the entire cohort, none of the exposures were related to overall cancer risk (HR_adj ApoA1 = 0.98, 95%CI: 0.95,1.01; HR_adj ApoB = 1.01, 95%CI: 0.98–1.04). Among men, ApoB was positively associated with cancer risk (HR_adj ApoB = 1.06, 95%CI: 1.01,1.10). Female breast cancer risk was inversely associated with ApoB (HR_adj = 0.92, 95%CI: 0.86,0.99). Among both genders, ApoA1 was inversely associated with lung cancer risk (HR_adj = 0.88, 95%CI: 0.80,0.97), whereas high ApoB increased lung cancer risk (HR_adj = 1.08, 95%CI: 0.99,1.18). Colorectal cancer risk was increased with high ApoB (HR_adj = 1.08, 95%CI: 1.01,1.16) among both genders. Apolipoprotein levels were not associated with prostate cancer incidence. Circulating levels of apolipoproteins are associated with overall cancer risk in men and across both genders with breast, lung and colorectal cancer risk. Validation of these findings may facilitate future primary prevention strategies for cancer.     

Contraceptive methods and ovarian cancer risk among Chinese women: A report from the Shanghai Women's Health Study

Oral contraceptive use is associated with reduced ovarian cancer risk; however, associations with other contraceptive methods, such as intrauterine device (IUD) and tubal ligation, are less clear. Women in China differ from western women in regard to mechanisms and duration of use of contraception. This study was undertaken to evaluate associations between contraceptive methods and ovarian cancer risk using data from the prospective Shanghai Women's Health Study. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated by Cox proportional hazards regression. A total of 174 epithelial ovarian cancer cases were found to occur among 70,259 women who were followed‐up for a total of 888,258 person‐years. The majority of women had ever used any contraception (77.0%), including IUD (55.6%), oral contraceptive (20.4%), tubal ligation (14.7%) or contraceptive shots (2.6%). Ever use of any contraception was associated with a nonsignificant reduction in ovarian cancer risk (HR: 0.86, 95% CI: 0.60–1.24). Longer duration of IUD use was associated with lower ovarian cancer risk (p‐value for trend = 0.04). Compared with never users, women with durations of IUD use longer than the median (20 years) were 38% less likely to develop ovarian cancer (HR: 0.62, 95% CI: 0.40–0.97). Based on the high prevalence and long duration of IUD use among Chinese women, we estimate a preventive fraction of 9.3%, corresponding to approximately 16 ovarian cancer cases. High prevalence of long‐term IUD use may, therefore, contribute to the low incidence of ovarian cancer observed in China.     

Oral contraceptive and IUD use and endometrial cancer: a population-based case-control study in Shanghai, China

Oral contraceptive (OC) and intrauterine device (IUD) use have been shown to be protective factors for endometrial cancer in several epidemiological studies; however, few studies have been conducted in Chinese populations. We evaluated the association between OC and IUD use and endometrial cancer risk in a population-based case-control study among Chinese women in Shanghai, China. The study included 1,204 newly diagnosed endometrial cancer cases and 1,212 age frequency-matched healthy controls. Logistic regression models were used to estimate adjusted odds ratios (OR) and their 95% confidence intervals (95% CI). In our study population, 18.5% cases and 24.9% controls reported having ever used OCs with an OR of 0.75 (95% CI, 0.60-0.93), after adjusting for known risk or protective factors for endometrial cancer. The risk of endometrial cancer decreased with long-term use of OCs with the OR for more than 72 months of use being 0.50 (95% CI, 0.30-0.85). The effect of OC use remained 25 or more years after cessation of use; the associated OR was 0.57 (95% CI = 0.42-0.78) as compared to nonusers. Similarly, fewer cases than controls had ever used IUD, with the multivariable adjusted OR being 0.53 (95% CI = 0.43-0.65). A reduction in risk was observed regardless the duration of use or age at first and last use. These results suggest that OC and IUD use may confer long-term protection against endometrial cancer.     

Reproductive factors,hormone use and gastric cancer risk: The Singapore Chinese Health Study

Gastric cancer incidence varies greatly worldwide, but is consistently twice as high in men than in women. The hormone‐related factors hypothesized to be associated with lower risk of gastric cancer in women have not been fully explored in populations with a high background risk of gastric cancer. The Singapore Chinese Health Study (SCHS) is a prospective cohort study in which 34,022 of the participants enrolled between 1993 and 1998 were women between 45 and 74 years of age. Information on reproductive histories, hormone replacement therapy (HRT) and oral contraceptive (OC) use was collected through in‐person interviews at baseline. As of December 31, 2013, 269 incident gastric cancer cases were identified. Multivariable‐adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to evaluate gastric cancer risk associations. Older age at natural menopause (≥55 versus <45 years: HR = 0.50, 95% CI: 0.25–0.99), type of menopause (other versus natural: HR = 0.48, 95% CI: 0.27–0.87) and greater years of menstrual cycling (fourth versus first quartile: HR = 0.67, 95% CI: 0.46–0.96) were associated with a decreased risk of gastric cancer. Ever use of OCs and HRT was also associated with reduced risk of gastric cancer; the multivariable‐adjusted HRs (95% CIs) were 0.40 (0.17–0.90) for use of HRT >3 years and 0.67 (0.47–0.94) for ever use of OCs, compared with never use. Reproductive factors associated with a longer window of fertility and the use of exogenous hormones were shown to reduce gastric cancer development in a cohort of Chinese women with a high background risk of gastric cancer.     

Hormonal factors and pancreatic cancer risk in women: The Malmö Diet and Cancer Study

The incidence of pancreatic cancer is leveling between sexes. Smoking, high age and heredity are established risk factors, but evidence regarding the influence of hormonal factors is unclear. In this study, we investigated the associations of reproductive factors, use of oral contraceptives (OC) and hormone replacement therapy (HRT) with pancreatic cancer risk in the Malmö Diet and Cancer Study, a prospective, population‐based cohort encompassing 17,035 women. Up until 31 December 2015, 110 women were identified with incident pancreatic cancer through the Swedish Cancer Registry. Higher age at menarche was significantly associated with pancreatic cancer risk (age‐adjusted [hazard ratio] HR = 1.17; 95% confidence interval [CI] 1.04–1.32, and fully adjusted HR = 1.17; 95% CI 1.04–1.32). Ever use of OC was not significantly associated with pancreatic cancer risk but ever use of HRT was significantly associated with a decreased risk of pancreatic cancer (age‐adjusted HR = 0.47, 95% CI 0.23–0.97, and fully adjusted HR = 0.48, 95% CI 0.23–1.00), in particular use of estrogen‐only regimen (age‐adjusted HR = 0.21; 95% CI 0.05–0.87 and fully adjusted HR = 0.22; 95% CI 0.05–0.90). Age at menopause or first childbirth, parity and breastfeeding history were not significantly associated with pancreatic cancer risk. Collectively, these findings suggest a protective role of female hormones against pancreatic cancer. Further studies are needed, and potential modifying genetic factors and indirect hazardous effects of smoking should also be considered.     

Association between metformin use after surgery for colorectal cancer and oncological outcomes: A nationwide register‐based study

Colorectal cancer is one of the most common malignancies in the Western world, and even after surgical removal, there is a high recurrence rate. Metformin treatment has been associated with a reduced risk of developing cancer, but whether metformin influences the risk of recurrence is unknown. The aim of our study was to examine the association between treatment with metformin and recurrence‐free, disease‐free survival and all‐cause mortality after surgery for colorectal cancer. The study was an observational register‐based study and included 25,785 patients, of which 1,116 had medically treated diabetes and 966 started metformin treatment at some point postoperatively. Diabetes was not associated with neither disease‐free (HR_adjusted = 1.09, 95% CI 0.97–1.21, p = 0.15) nor recurrence‐free survival (HR_adjusted = 1.13, 95% CI 0.95–1.35, p = 0.17). The study found no difference in regards to disease‐free or recurrence‐free survival between the metformin treated group (HR_RFS = 1.06, 95% CI 0.87–1.15, p = 0.57, HR_DFS = 1.01, 95% CI 0.89–1.15, p = 0.85) and non‐diabetic patients. Patients with diabetes had increased all‐cause mortality (HR_adjusted = 1.29, 95% CI 1.16–1.45, p < 0.0001). Metformin treatment did not affect all‐cause mortality (HR = 1.07, 95% CI 0.94–1.22, p = 0.33) compared to non‐diabetic patients. In conclusion, our study did not find an association between diabetes or metformin treatment and recurrence‐free or disease‐free survival after surgery for colorectal cancer. However, diagnosis of diabetes is associated with increased all‐cause mortality.     

The prognostic impact of COX‐2 expression in breast cancer depends on oral contraceptive history,preoperative NSAID use,and tumor size

The association between tumor cyclooxygenase 2 (COX‐2) expression and breast cancer prognosis has been inconsistent. The purpose of this study was to evaluate the prognostic significance of COX‐2 tumor expression according to adjuvant treatment, and potential effect modifications of non‐steroid anti‐inflammatory drug (NSAID) use, and other tumor and lifestyle factors. A prospective cohort of 1,116 patients with primary breast cancer in Lund, Sweden, included 2002‐2012 was followed until June 2014 (median 5 years). Tumor‐specific COX‐2 expression was evaluated on tissue microarrays using immunohistochemistry. Associations between COX‐2 intensity (negative, weak‐moderate, high) and patient and tumor characteristics as well as prognosis were analyzed. Tumor‐specific COX‐2 expression was available for 911 patients and was significantly associated with higher age at diagnosis and less aggressive tumor characteristics. Higher COX‐2 expression was associated with lower risk for breast cancer events during the first five years of follow‐up, _adjHR 0.60 (95%CI: 0.37‐0.97), per category. The association between COX‐2 expression and prognosis was significantly modified by oral contraceptive (OC) use (P_interaction = 0.048), preoperative NSAID use (P_interaction = 0.009), and tumor size (P_interaction = 0.039). COX‐2 negativity was associated with increased risk for events during the first five years in ever OC users, _adjHR 1.94 (1.01‐3.72) and during the 11‐year follow‐up in preoperative NSAID users, _adjHR 4.51 (1.18‐11.44) as well as in patients with large tumors, _adjHR 2.57 (1.28‐5.15). In conclusion, this study, one of the largest evaluating COX‐2 expression in breast cancer, indicates that the prognostic impact of COX‐2 expression depends on host factors and tumor characteristics.     

Adolescent and mid‐life diet and subsequent risk of thyroid cancer in the NIH‐AARP diet and health study

Although thyroid cancer is suspected to have a nutritional etiology, prospective studies examining the relationship between diet and thyroid cancer are lacking. During 1996–1997, NIH‐AARP Diet and Health Study participants, ages 51–72 years, completed a 37‐item food frequency questionnaire about diet at ages 12–13 years (adolescence) and 10 years before baseline (mid‐life). Over a median 10 years of follow‐up, 325 individuals (143 men and 182 women) were diagnosed with thyroid cancer. Multivariable‐adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for intakes of foods and food groups comparing the highest to the lowest quartiles. Adolescent intakes of chicken/turkey (HR = 1.59, 95% CI: 0.97–2.60; p_trend < 0.01) and sweet baked goods (HR = 1.59, 95% CI: 1.09–2.34; p_trend = 0.04) were positively associated with thyroid cancer risk, while intake of butter/margarine was inversely associated with risk (HR = 0.64, 95% CI: 0.44–0.91; p_trend < 0.02). Similar to adolescent diet, mid‐life intake of sweet baked goods was nonsignificantly associated with an increased risk of thyroid cancer (HR = 1.39, 95% CI: 0.96–2.00; p_trend = 0.11), but intake of butter/margarine was inversely associated with risk (HR = 0.66, 95% CI: 0.46–0.95; p_trend = 0.03). Among men, higher adolescent consumption of canned tuna was positively associated with risk of thyroid cancer (HR = 1.69, 95% CI: 1.01–2.83; p_trend = 0.03), and greater mid‐life intake of broccoli was associated with a twofold increased risk (HR = 2.13, 95% CI: 1.13–3.99; p_trend < 0.01). This large prospective study suggests that several components of the adolescent and mid‐life diet, including iodine‐rich foods and goitrogens, may influence thyroid cancer risk.     

Association of breast cancer risk loci with breast cancer survival

The survival of breast cancer patients is largely influenced by tumor characteristics, such as TNM stage, tumor grade and hormone receptor status. However, there is growing evidence that inherited genetic variation might affect the disease prognosis and response to treatment. Several lines of evidence suggest that alleles influencing breast cancer risk might also be associated with breast cancer survival. We examined the associations between 35 breast cancer susceptibility loci and the disease over‐all survival (OS) in 10,255 breast cancer patients from the National Cancer Institute Breast and Prostate Cancer Cohort Consortium (BPC3) of which 1,379 died, including 754 of breast cancer. We also conducted a meta‐analysis of almost 35,000 patients and 5,000 deaths, combining results from BPC3 and the Breast Cancer Association Consortium (BCAC) and performed in silico analyses of SNPs with significant associations. In BPC3, the C allele of LSP1‐rs3817198 was significantly associated with improved OS (HR_per‐allele=0.70; 95% CI: 0.58–0.85; p_trend = 2.84 × 10^?4; HR_{heterozygotes} = 0.71; 95% CI: 0.55–0.92; HR_homozygotes = 0.48; 95% CI: 0.31–0.76; p_2DF = 1.45 × 10^?3). In silico, the C allele of LSP1‐rs3817198 was predicted to increase expression of the tumor suppressor cyclin‐dependent kinase inhibitor 1C (CDKN1C). In the meta‐analysis, TNRC9‐rs3803662 was significantly associated with increased death hazard (HR_META =1.09; 95% CI: 1.04–1.15; p_trend = 6.6 × 10^?4; HR_{heterozygotes} = 0.96 95% CI: 0.90–1.03; HR_homozygotes = 1.21; 95% CI: 1.09–1.35; p_2DF=1.25 × 10^?4). In conclusion, we show that there is little overlap between the breast cancer risk single nucleotide polymorphisms (SNPs) identified so far and the SNPs associated with breast cancer prognosis, with the possible exceptions of LSP1‐rs3817198 and TNRC9‐rs3803662.     

Oral contraceptives, menopausal hormone therapy use and risk of B-cell non-Hodgkin lymphoma in the California Teachers Study

We examined oral contraceptive (OC) and menopausal hormonal therapy (MHT) use in relation to risk of B-cell non-Hodgkin lymphoma (NHL). Women under age 85 years participating in the California Teachers Study with no history of hematopoietic cancer were followed from 1995 through 2007. A total of 516 of 114,131 women eligible for OC use analysis and 402 of 54,758 postmenopausal women eligible for MHT use analysis developed B-cell NHL. Multivariable adjusted and age stratified Cox proportional hazards models were fit to estimate relative risks (RRs) and 95% confidence intervals (95% CI). Ever versus never OC use was marginally associated with lower B-cell NHL risk, particularly among women first using OCs before age 25 years (RR=0.72, 95% CI=0.51-0.99); yet, no duration-response effect was observed. No association was observed for ever versus never MHT use among postmenopausal women (RR=1.05, 95% CI=0.83-1.33) overall or by formulation (estrogen alone, ET, or estrogen plus progestin, EPT). Among women with no MHT use, having bilateral oophorectomy plus hysterectomy was associated with greater B-cell NHL risk than having natural menopause (RR=3.15, 95% CI=1.62-6.13). Bilateral oophorectomy plus hysterectomy was not associated with risk among women who used ET or EPT. These results indicate that exogenous hormone use does not strongly influence B-cell NHL risk.     

Sex hormones and the risk of keratinocyte cancers among women in the United States: A population‐based case–control study

Men are at a higher risk of developing both squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) than women, but there is emerging evidence that women may be experiencing greater increases in the incidence rates of these malignancies than men. One possible explanation is the expanding use of sex steroids among women, although only a few studies have examined this hypothesis. As part of a population‐based, case–control study of women in New Hampshire, USA, we sought to evaluate the risk of SCC, BCC, and early‐onset BCC in relation to exogenous and endogenous sex hormones. We found that oral contraceptive (OC) use was associated with an increased risk of SCC (OR = 1.4, 95% CI = 1.1–1.8) and BCC (OR = 1.4, 95% CI = 1.0‐1.8), particularly high estrogen dose (>50 mg) OC use. Hormone replacement therapy (HRT) use also related to SCC, with an elevated OR largely for progestin use (OR = 1.4, 95% CI = 1.1–1.8). Additionally, both OC use and combination HRT use were associated with more aggressive BCC subtypes. In contrast, menstrual and reproductive history did not appear to influence keratinocyte cancer risk in our data. Our findings provide evidence that use of sex steroids may enhance risk of keratinocyte cancer.     

Inflammatory potential of diet and risk of pancreatic cancer in the Prostate,Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial

Inflammation plays a central role in pancreatic cancer etiology and can be modulated by diet. We aimed to examine the association between the inflammatory potential of diet, assessed with the Dietary Inflammatory Index (DII®), and pancreatic cancer risk in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial prospective cohort. Our study included 101,449 participants aged 52–78 years at baseline who completed both baseline questionnaire and a diet history questionnaire. Energy‐adjusted DII (E‐DII) scores were computed based on food and supplement intake. Cox proportional hazards models and time dependent Cox models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) with participants in the lowest E‐DII quintile (most anti‐inflammatory scores) as referent. After a median 8.5 years of follow‐up, 328 pancreatic cancer cases were identified. E‐DII scores were not associated with pancreatic cancer risk in the multivariable model (HR_Q5vsQ1 = 0.94; 95% CI = 0.66–1.35; p‐trend = 0.43). Time significantly modified the association (p‐interaction = 0.01). During follow up <4 years, there was suggestive evidence of an inverse association between E‐DII and pancreatic cancer (HR_Q5vsQ1 = 0.60; 95% CI = 0.35–1.02; p‐trend = 0.20) while there was a significant positive trend in the follow up ≥4 years (HR_Q5vsQ1 = 1.31; 95% CI = 0.83–2.08; p‐trend = 0.03). Similar results were observed for E‐DII from food only. Our study does not support an association between inflammatory potential of diet and pancreatic cancer risk; however, heterogeneous results were obtained with different follow‐up times. These divergent associations may result from the influences of undetected disease in the short‐term.     

No effect of meat,meat cooking preferences,meat mutagens or heme iron on lung cancer risk in the prostate,lung, colorectal and ovarian cancer screening trial

Recent epidemiological studies have suggested that red and processed meat may increase the risk of lung cancer. Possible underlying mechanisms include mutagens produced during high‐temperature cooking or preservation, or formed endogenously from heme iron in meat. We used data from 99,579 participants of both screened and nonscreened arms of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, aged 55–74 years, to investigate whether meat type, cooking method, doneness level, intake of specific meat mutagens 2‐amino‐3,8‐dimethylimidazo[4,5‐f]quinoxaline (MeIQx), 2‐amino‐3,4,8‐trimethylimidazo[4,5‐f]quinoxaline] (DiMeIQx), 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP) and benzo(a)pyrene (B(a)P)] and heme iron are associated with lung cancer. Participants' diet was assessed prospectively using a 124‐item food frequency questionnaire and an additional meat‐cooking module. Dietary data were used in conjunction with a database to estimate intake of MeIQx, DiMeIQx, PhIP, B(a)P and heme iron. After up to 8 years of follow‐up, 782 incident lung cancer cases were ascertained. Lung cancer risk was not associated with the consumption of either red (men: HR_{Q5 vs. Q1} = 1.11, 95% CI = 0.79–1.56, P_trend = 0.42; women: HR_{Q5 vs. Q1} = 1.30, 95% CI = 0.87–1.95, P_trend = 0.65) or processed meat (men: HR_{Q5 vs. Q1} = 1.12, 95% CI = 0.83–1.53, P_trend = 0.22; women: HR_{Q5 vs. Q1} = 0.98, 95% CI = 0.68–1.41, P_trend = 0.32) in multivariable models. High‐temperature cooking methods, level of meat doneness, meat mutagens and heme iron had no effect on lung cancer risk. In this population, we found no association between meat type, cooking method, doneness level or intake of specific meat mutagens or heme iron and lung cancer risk.     

Menopausal hormone therapy use and risk of primary liver cancer in the clinical practice research datalink

Primary liver cancer occurs less commonly among women than men in almost all countries. This discrepancy has suggested that hormone levels and/or exogenous hormone use could have an effect on risk, although prior studies have reached inconsistent conclusions. Thus, the current study was conducted to examine the relationship between menopausal hormone therapy (MHT) use and development of liver cancer. A nested case‐control study was conducted within the United Kingdom's Clinical Practice Research Datalink (CPRD). Controls were matched, at a 4‐to‐1 ratio, to women diagnosed with primary liver cancer between 1988 and 2011. A second match, based on whether the cases and controls had diabetes, was also conducted. Odds ratios (OR) and 95% confidence intervals (95%CI) for associations of MHT with liver cancer were estimated using conditional logistic regression adjusted for known risk factors. In the overall match, 339 women with liver cancer were matched to 1318 controls. MHT use was associated with a significantly lower risk of liver cancer (OR_adj = 0.58, 95%CI = 0.37–0.90) especially among users of estrogen‐only MHT (OR_adj = 0.44, 95%CI = 0.22–0.88) and among past users (OR_adj = 0.53, 95%CI = 0.32–0.88). Among the matched cases (n = 58) and controls (n = 232) with diabetes, the odds ratios were similar to the overall analysis (OR_adj = 0.57, 95%CI = 0.09–3.53), but did not attain statistical significance. In the current study, MHT use, especially estrogen‐only MHT use, was associated with a significantly lower risk of liver cancer. These results support the need of further investigation into whether hormonal etiologies can explain the variation in liver cancer incidence between men and women.     

Lifetime risk of distinct upper aerodigestive tract cancers and consumption of alcohol,betel and cigarette

The cancer of upper aerodigestive tract (UADT) is a common cancers in the world. However, its lifetime risk by consumption of alcohol, betel and cigarettes remain to be elucidated. This study aimed to estimate lifetime risk of distinct UADT cancers and assess their associations with alcohol, betel and cigarette consumption. Three cohorts of 25,611 men were enrolled in 1982–1992 in Taiwan. The history of alcohol, betel and cigarette consumption was enquired through questionnaire interview. Newly developed UADT cancers were ascertained through computerized linkage with national cancer registry profile. Lifetime (30–80 years old) risk and multivariate‐adjusted hazard ratio (HR_adj) of distinct UADT cancers by alcohol, betel and cigarette consumption were estimated. A total of 269 pathologically confirmed cases of UADT cancers were newly‐diagnosed during 472,096 person‐years of follow‐up. The lifetime risk of UADT cancer was 9.42 and 1.65% for betel chewers and nonchewers, 3.22 and 1.21% for cigarette smokers and nonsmokers and 4.77 and 1.85% for alcohol drinkers and nondrinkers. The HR_adj (95% confidence interval) of developing UADT cancer was 3.36 (2.51–4.49), 2.02 (1.43–2.84), 1.90 (1.46–2.49), respectively, for the consumption of betel, cigarette and alcohol. Alcohol, betel and cigarette had different effect on cancers at various anatomical sites of UADT. The cancer risk from the mouth, pharynx, esophagus to larynx increased for alcohol and cigarette consumption, but decreased for betel consumption. Alcohol, betel and cigarette consumption are independent risk predictors for distinct UADT cancers.     

Predicted basal metabolic rate and cancer risk in the European Prospective Investigation into Cancer and Nutrition

Emerging evidence suggests that a metabolic profile associated with obesity may be a more relevant risk factor for some cancers than adiposity per se. Basal metabolic rate (BMR) is an indicator of overall body metabolism and may be a proxy for the impact of a specific metabolic profile on cancer risk. Therefore, we investigated the association of predicted BMR with incidence of 13 obesity-related cancers in the European Prospective Investigation into Cancer and Nutrition (EPIC). BMR at baseline was calculated using the WHO/FAO/UNU equations and the relationships between BMR and cancer risk were investigated using multivariable Cox proportional hazards regression models. A total of 141,295 men and 317,613 women, with a mean follow-up of 14 years were included in the analysis. Overall, higher BMR was associated with a greater risk for most cancers that have been linked with obesity. However, among normal weight participants, higher BMR was associated with elevated risks of esophageal adenocarcinoma (hazard ratio per 1-standard deviation change in BMR [HR_1-SD]: 2.46; 95% CI 1.20; 5.03) and distal colon cancer (HR_1-SD: 1.33; 95% CI 1.001; 1.77) among men and with proximal colon (HR_1-SD: 1.16; 95% CI 1.01; 1.35), pancreatic (HR_1-SD: 1.37; 95% CI 1.13; 1.66), thyroid (HR_1-SD: 1.65; 95% CI 1.33; 2.05), postmenopausal breast (HR_1-SD: 1.17; 95% CI 1.11; 1.22) and endometrial (HR_1-SD: 1.20; 95% CI 1.03; 1.40) cancers in women. These results indicate that higher BMR may be an indicator of a metabolic phenotype associated with risk of certain cancer types, and may be a useful predictor of cancer risk independent of body fatness.     

Long and irregular menstrual cycles,polycystic ovary syndrome,and ovarian cancer risk in a population‐based case‐control study

Long and irregular menstrual cycles, a hallmark of polycystic ovary syndrome (PCOS), have been associated with higher androgen and lower sex hormone binding globulin levels and this altered hormonal environment may increase the risk of specific histologic subtypes of ovarian cancer. We investigated whether menstrual cycle characteristics and self‐reported PCOS were associated with ovarian cancer risk among 2,041 women with epithelial ovarian cancer and 2,100 controls in the New England Case‐Control Study (1992–2008). Menstrual cycle irregularity, menstrual cycle length, and PCOS were collected through in‐person interview. Unconditional logistic regression models were used to calculate odds ratios (OR) and 95% confidence intervals (95% CIs) for ovarian cancer risk overall, and polytomous logistic regression to evaluate whether risk differed between histologic subtypes. Overall, we observed no elevation in ovarian cancer risk for women who reported periods that were never regular or for those reporting a menstrual cycle length of >35 days with ORs of 0.87 (95% CI = 0.69–1.10) and 0.83 (95% CI = 0.44–1.54), respectively. We observed no overall association between self‐reported PCOS and ovarian cancer (OR = 0.97; 95% CI = 0.61–1.56). However, we observed significant differences in the association with menstrual cycle irregularity and risk of ovarian cancer subtypes (p_{heterogeneity} = 0.03) as well as by BMI and OC use (p_interaction < 0.01). Most notable, menstrual cycle irregularity was associated with a decreased risk of high grade serous tumors but an increased risk of serous borderline tumors among women who had never used OCs and those who were overweight. Future research in a large collaborative consortium may help clarify these associations.     

Ingested nitrate and nitrite,disinfection by‐products,and pancreatic cancer risk in postmenopausal women

Nitrate and nitrite are precursors of N‐nitroso compounds (NOC), probable human carcinogens that cause pancreatic tumors in animals. Disinfection by‐products (DBP) exposures have also been linked with digestive system cancers, but few studies have evaluated relationships with pancreatic cancer. We investigated the association of pancreatic cancer with these drinking water contaminants and dietary nitrate/nitrite in a cohort of postmenopausal women in Iowa (1986–2011). We used historical monitoring and treatment data to estimate levels of long‐term average nitrate and total trihalomethanes (TTHM; the sum of the most prevalent DBP class) and the duration exceeding one‐half the maximum contaminant level (>½ MCL; 5 mg/L nitrate‐nitrogen, 40 µg/L TTHM) among participants on public water supplies (PWS) >10 years. We estimated dietary nitrate and nitrite intakes using a food frequency questionnaire. We computed hazard ratios (HR) and 95% confidence intervals (CI) using Cox regression and evaluated nitrate interactions with smoking and vitamin C intake. We identified 313 cases among 34,242 women, including 152 with >10 years PWS use (N = 15,710). Multivariable models of average nitrate showed no association with pancreatic cancer (HR_{p95 vs. Q1} = 1.16, 95% CI: 0.51–2.64). Associations with average TTHM levels were also null (HR_{Q4 vs. Q1} = 0.70, 95% CI:0.42–1.18). We observed no trend with increasing years of exposure to either contaminant at levels >½ MCL. Positive associations were suggested in the highest dietary nitrite intake from processed meat (HR_{p95 vs. Q1} = 1.66, 95% CI 1.00–2.75;p_trend = 0.05). We found no interactions of nitrate with known modifiers of endogenous NOC formation. Our results suggest that nitrite intake from processed meat may be a risk factor for pancreatic cancer.     

Presence of autoimmune disease affects not only risk but also survival in patients with B‐cell non‐Hodgkin lymphoma

Although autoimmune diseases (AIDs) are known to predispose to non‐Hodgkin lymphoma (NHL), their association with NHL prognosis has rarely been investigated. We examined associations between autoimmunity and B‐cell NHL onset by comparing AID history (determined by self‐report and medication review and supplemented by chart review where possible) among 435 adult B‐NHL patients in Hadassah‐Hebrew University Medical Center, diagnosed 2009‐2014, and 414 age‐and‐sex frequency‐matched controls. We examined AIDs as a whole, B‐ and T‐cell–mediated AIDs, and autoimmune thyroid diseases. Among cases, we used Kaplan‐Meier and Cox regression models to assess the association of AID with overall survival and relapse‐free survival, adjusting for prognostically important patient and disease characteristics such as Ki67% staining, International Prognostic Index, rituximab treatment, and histological subgroup. Autoimmune diseases were associated with B‐NHL (odds ratio [OR] = 1.95; 95% confidence interval (CI), 1.31‐2.92), especially AIDs mediated by B‐cell activation (OR = 5.20; CI, 1.90‐14.3), which were particularly associated with marginal zone lymphoma (OR = 19.3; CI, 4.59‐80.9). We found that time to relapse for all B‐NHL patients with AIDs was significantly shorter (mean of 49.21 mo [±3.22]) than among patients without AID (mean of 59.74 mo [±1.62]), adjusted hazard ratio [HR_adj] = 1.69 (CI, 1.03‐2.79). Specifically, in patients with diffuse large B‐cell lymphoma, of whom 91.8% had received rituximab, a history of B‐cell–mediated AIDs was associated with shorter relapse‐free survival and overall survival, HR_adj = 8.34 (CI, 3.01‐23.1) and HR_adj = 3.83 (CI, 1.20‐12.3), respectively. Beyond confirming the well‐known association between AIDs and B‐NHL, we found that AID is an adverse prognostic factor in B‐cell lymphoma, associated with a shortened time to relapse, suggesting that there are specific therapeutic challenges in the subgroup of patients suffering from both these diseases. Further work is required to address mechanisms of resistance to standard treatment in the setting of AID‐associated B‐NHL. In the era of immunotherapy, these findings have particular relevance.