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Casagrande DS, Rosa DD, Umpierre D, Sarmento RA, Rodrigues CG, Schaan BD. Incidence of cancer following bariatric surgery: systematic review and meta-analysis. Obes Surg 2015; 24:1499-509. [PMID: 24817500 DOI: 10.1007/s11695-014-1276-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Obesity is linked to the development of cancer. Previous studies have suggested that there is a relationship between bariatric surgery and reduced cancer risk. Data sources were from Medline, Embase, and Cochrane Library. From 951 references, 13 studies met the inclusion criteria (54,257 participants). In controlled studies, bariatric surgery was associated with a reduction in the risk of cancer. The cancer incidence density rate was 1.06 cases per 1000 person-years within the surgery groups. In the meta-regression, we found an inverse relationship between the presurgical body mass index and cancer incidence after surgery (beta coefficient -0.2, P < 0.05). Bariatric surgery is associated with reduced cancer risk in morbidly obese people. However, considering the heterogeneity among the studies, conclusions should be drawn with care.
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Affiliation(s)
- Daniela Schaan Casagrande
- Postgraduate Program in Medical Sciences: Endocrinology and Metabolism, Universidade Federal do Rio Grande do Sul, Hospital de Clínicas de Porto Alegre, Rua Ramiro Barcelos 2350, prédio 12, 4° andar, 90035-003, Porto Alegre, RS, Brazil
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52
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Benedetto C, Salvagno F, Canuto EM, Gennarelli G. Obesity and female malignancies. Best Pract Res Clin Obstet Gynaecol 2015; 29:528-40. [DOI: 10.1016/j.bpobgyn.2015.01.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 01/28/2015] [Indexed: 12/26/2022]
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53
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Song M, Hu FB, Spiegelman D, Chan AT, Wu K, Ogino S, Fuchs CS, Willett WC, Giovannucci EL. Adulthood Weight Change and Risk of Colorectal Cancer in the Nurses' Health Study and Health Professionals Follow-up Study. Cancer Prev Res (Phila) 2015; 8:620-7. [PMID: 25930050 DOI: 10.1158/1940-6207.capr-15-0061] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/14/2015] [Indexed: 02/06/2023]
Abstract
We investigated the association between adulthood weight change and colorectal cancer risk in a prospective study with 24 to 34 years of follow-up among 90,988 women and 46,679 men. The primary exposures included weight change from early adulthood (age = 18 years for women, 21 years for men) to baseline enrollment (median age = 43 years for women, 52 years for men), and from baseline to present. In the secondary analyses, we also assessed 4-year weight change during follow-up, and during premenopausal (from age 18 years to menopause) and postmenopausal (from menopause to present) periods in women. Compared to men maintaining their weight from age 21 to baseline, those who gained 20 kg or more were at a higher risk of colorectal cancer (relative risk [RR], 1.64; 95% confidence interval [CI], 1.15-2.35, Ptrend < 0.001), whereas those who lost 8 kg or more had a lower risk (RR, 0.61; 95% CI, 0.30-1.22, Ptrend = 0.003). Similar but weaker associations were found in women and the corresponding RRs were 1.38 (95% CI, 1.13-1.69, Ptrend < 0.001) and 0.80 (95% CI, 0.58-1.09, Ptrend = 0.21). Weight change from baseline to present was not associated with colorectal cancer risk. Four-year weight change during follow-up was positively associated with colorectal cancer risk in men (Ptrend = 0.03) but not in women (Ptrend = 0.42). In addition, in women, weight change before, but not after, menopause was associated with colorectal cancer risk. Our findings provide further scientific rationale for recommendations to maintain a healthy body weight during adulthood. A potential differential association according to sex and timing of weight change warrants further investigation.
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Affiliation(s)
- Mingyang Song
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Frank B Hu
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Channing Division of Network Medicine, Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Donna Spiegelman
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Andrew T Chan
- Channing Division of Network Medicine, Department of Medicine, Harvard Medical School, Boston, Massachusetts. Division of Gastroenterology, Massachusetts General Hospital, Boston, Massachusetts
| | - Kana Wu
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - Shuji Ogino
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Channing Division of Network Medicine, Department of Medicine, Harvard Medical School, Boston, Massachusetts. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts. Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Charles S Fuchs
- Channing Division of Network Medicine, Department of Medicine, Harvard Medical School, Boston, Massachusetts. Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - Walter C Willett
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Channing Division of Network Medicine, Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Edward L Giovannucci
- Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Channing Division of Network Medicine, Department of Medicine, Harvard Medical School, Boston, Massachusetts.
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54
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O'Rourke RW. Obesity and cancer: at the crossroads of cellular metabolism and proliferation. Surg Obes Relat Dis 2014; 10:1208-19. [PMID: 25264328 PMCID: PMC4267907 DOI: 10.1016/j.soard.2014.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 08/19/2014] [Accepted: 08/21/2014] [Indexed: 12/14/2022]
Abstract
Obesity is associated with an increased risk of cancer. The mechanisms underlying this association include but are not limited to increased systemic inflammation, an anabolic hormonal milieu, and adipocyte-cancer crosstalk, aberrant stimuli that conspire to promote neoplastic transformation. Cellular proliferation is uncoupled from nutrient availability in malignant cells, promoting tumor progression. Elucidation of the mechanisms underlying the obesity-cancer connection will lead to the development of novel metabolism-based agents for cancer prevention and treatment.
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Affiliation(s)
- Robert W O'Rourke
- Department of Surgery, University of Michigan and Ann Arbor VA Hospital, Ann Arbor, Michigan.
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Parkin E, O'Reilly DA, Sherlock DJ, Manoharan P, Renehan AG. Excess adiposity and survival in patients with colorectal cancer: a systematic review. Obes Rev 2014; 15:434-51. [PMID: 24433336 DOI: 10.1111/obr.12140] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 11/21/2013] [Accepted: 12/04/2013] [Indexed: 12/19/2022]
Abstract
Excess adiposity is an established risk factor for incident colorectal cancer (CRC) but whether this association extrapolates to poorer survival is unclear. We undertook a systematic review to examine relationships between measures of adiposity and survival in patients with CRC. For distinction, we included pre-diagnosis exposure and CRC-related mortality. We performed dose-response meta-analyses and assessed study quality using eight domains of bias. Six study categories were identified based on (i) timing of adiposity measurement relative to survival analysis time zero and (ii) clinical setting. Several types of adiposity measurements were reported; body mass index (BMI) was the commonest. For pre-diagnosis cohorts, baseline BMI negatively impacted on CRC-related mortality in men only (risk estimate per 5 kg m(-2) = 1.19, 95% confidence intervals: 1.14-1.25). The other groups were pre-diagnosis BMI but diagnosis as time zero; population-based cohorts; treatment cohorts; observational analyses within adjuvant chemotherapy trials; patients with metastatic CRC - each had several biases (e.g. treatment selection, reverse causality) and sources of confounding (e.g. chemotherapy 'capping'). Overall, there was insufficient evidence for a strong link between adiposity and survival. These findings demonstrate an important principle: an established link between an exposure (here, adiposity) and increased cancer incidence does not necessarily extrapolate into an inferior post-treatment outcome.
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Affiliation(s)
- Edward Parkin
- Institute of Cancer Sciences, University of Manchester, Manchester, UK; Department of Hepatobiliary Surgery, North Manchester General Hospital, Manchester, UK
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56
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Barry JA, Azizia MM, Hardiman PJ. Risk of endometrial, ovarian and breast cancer in women with polycystic ovary syndrome: a systematic review and meta-analysis. Hum Reprod Update 2014; 20:748-58. [PMID: 24688118 PMCID: PMC4326303 DOI: 10.1093/humupd/dmu012] [Citation(s) in RCA: 305] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Polycystic ovary syndrome (PCOS) is a common condition affecting ∼8% of women. The objective of the present study was to quantify separately the risk of endometrial cancer, ovarian cancer and breast cancer in women with PCOS compared with non-PCOS controls, and quantify separately the risk to women of all ages as well as the risk to premenopausal women. METHODS We conducted a systematic review and meta-analysis of observational studies. Studies were eligible for inclusion if they compared women with PCOS to non-PCOS groups for fatal or non-fatal gynaecological cancers. Studies listed in MEDLINE and EMBASE published up to 7 October 2013 in any language were identified, and relevant papers were also searched by hand. Relevant data (for example, study design, source of control data, diagnostic criteria) were extracted and tabulated. RESULTS From 698 references, 11 studies (5 of endometrial cancer and 3 each of ovarian and breast cancer) met the inclusion criteria for the meta-analysis (919 women with PCOS and 72054 non-PCOS controls). Using the Mantel–Haenszel method, with fixed or random effects model as appropriate, women with PCOS were at a significantly increased risk of endometrial cancer (odds ratio (OR), 2.79; 95% confidence interval (CI), 1.31–5.95, P < 0.008), but the risk of ovarian and breast cancers was not significantly increased (OR, 1.41; 95% CI, 0.93–2.15, P < 0.11 and OR, 0.95; 95% CI, 0.64–1.39, P < 0.78, respectively). However when studies which included women aged over 54 years were excluded from the analysis, the risk for women with PCOS increased further for endometrial cancer (OR, 4.05; 95% CI, 2.42–6.76, P < 0.00001), became significantly increased for ovarian cancer (OR, 2.52; 95% CI, 1.08–5.89, P < 0.03), but remained non-significant for breast cancer (OR, 0.78; 95% CI, 0.46–1.32, P < 0.35). CONCLUSIONS This is the first meta-analysis to examine gynaecological cancers in women with PCOS younger than 54 years of age compared with controls of similar age. Current data suggest that women of all ages with PCOS are at an increased risk of endometrial cancer but the risk of ovarian and breast cancer was not significantly increased overall. These results highlight the potential risk of gynaecological cancer morbidities associated with PCOS. However, the available evidence is far from robust and variation in diagnostic criteria for PCOS, associated risk factors (particularly obesity), and selection bias in the studies may have resulted in an exaggeration of the increased risk. Furthermore, women who have PCOS should also be made aware that any increased risk for endometrial cancer must be judged in the context of its relatively low incidence in the general population. A large well-controlled prospective study is required in order to gain a more accurate estimate of the risk of gynaecological cancers in women with PCOS. PROSPERO CRD REGISTRATION NUMBER CRD42012003500.
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Affiliation(s)
- John A Barry
- Institute for Women's Health, University College London Medical School, London NW3 2PF, UK
| | - Mallika M Azizia
- Institute for Women's Health, University College London Medical School, London NW3 2PF, UK
| | - Paul J Hardiman
- Institute for Women's Health, University College London Medical School, London NW3 2PF, UK
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Anderson AS, Craigie AM, Caswell S, Treweek S, Stead M, Macleod M, Daly F, Belch J, Rodger J, Kirk A, Ludbrook A, Rauchhaus P, Norwood P, Thompson J, Wardle J, Steele RJC. The impact of a bodyweight and physical activity intervention (BeWEL) initiated through a national colorectal cancer screening programme: randomised controlled trial. BMJ 2014; 348:g1823. [PMID: 24609919 PMCID: PMC3945930 DOI: 10.1136/bmj.g1823] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/20/2014] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To evaluate the impact of a diet and physical activity intervention (BeWEL) on weight change in people with a body mass index >25 weight (kg)/height (m)(2) at increased risk of colorectal cancer and other obesity related comorbidities. DESIGN Multicentre, parallel group, randomised controlled trial. SETTING Four Scottish National Health Service health boards. PARTICIPANTS 329 overweight or obese adults (aged 50 to 74 years) who had undergone colonoscopy after a positive faecal occult blood test result, as part of the national bowel screening programme, and had a diagnosis of adenoma confirmed by histopathology. 163 were randomised to intervention and 166 to control. INTERVENTION Participants were randomised to a control group (weight loss booklet only) or 12 month intervention group (three face to face visits with a lifestyle counsellor plus monthly 15 minute telephone calls). A goal of 7% reduction in body weight was set and participants received a personalised energy prescription (2508 kJ (600 kcal) below that required for weight maintenance) and bodyweight scales. Motivational interviewing techniques explored self assessed confidence, ambivalence, and personal values concerning weight. Behavioural strategies included goal setting, identifying intentions of implementation, self monitoring of body weight, and counsellor feedback about reported diet, physical activity, and weight change. MAIN OUTCOME MEASURES The primary outcome was weight change over 12 months. Secondary outcomes included changes in waist circumference, blood pressure, fasting cardiovascular biomarkers, and glucose metabolism variables, physical activity, diet, and alcohol consumption. RESULTS At 12 months, data on the primary outcome were available for 148 (91%) participants in the intervention group and 157 (95%) in the control group. Mean weight loss was 3.50 kg (SD 4.91) (95% confidence interval 2.70 to 4.30) in the intervention group compared with 0.78 kg (SD 3.77) (0.19 to 1.38) in the control group. The group difference was 2.69 kg (95% confidence interval 1.70 to 3.67). Differences between groups were significant for waist circumference, body mass index, blood pressure, blood glucose level, diet, and physical activity. No reported adverse events were considered to be related to trial participation. CONCLUSIONS Significant weight loss can be achieved by a diet and physical activity intervention initiated within a national colorectal cancer screening programme, offering considerable potential for risk reduction of disease in older adults. TRIAL REGISTRATION Current Controlled Trials ISRCTN53033856.
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Affiliation(s)
- Annie S Anderson
- Centre for Research into Cancer Prevention and Screening, Cancer Division, Medical Research Institute, Ninewells Medical School, Dundee, UK
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Moon HS, Mantzoros CS. Regulation of cell proliferation and malignant potential by irisin in endometrial, colon, thyroid and esophageal cancer cell lines. Metabolism 2014; 63:188-93. [PMID: 24268368 DOI: 10.1016/j.metabol.2013.10.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 09/17/2013] [Accepted: 10/15/2013] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Irisin is a novel hormone that has been proposed to mediate the beneficial effects of exercise on metabolism, including body weight regulation and insulin resistance. No previous studies have evaluated whether irisin may regulate cell proliferation and malignant potential of obesity-related cancer cell lines. MATERIALS/METHODS Cell proliferation and malignant potential i.e. cell adhesion and colony formation were studied in vitro using human and mouse obesity-related cancer cell lines i.e. endometrial (KLE and RL95-2), colon (HT29 and MCA38), thyroid (SW579 and BHP7) and esophageal (OE13 and OE33). RESULTS We observed that, in contrast to metformin, cell proliferation is not regulated by irisin in a dose-dependent manner in human and mouse obesity-related cancer cell lines. Specifically, physiological (5 to 10 nmol/L) and high physiological/pharmacological (50 to 100 nmol/L) concentrations of irisin had no effect on cell proliferation when compared to control in human and mouse endometrial, colon, thyroid and esophageal cancer cell lines. Also, we observed that, in contrast to metformin, neither physiological nor high physiological/pharmacological concentrations of irisin regulate cell adhesion and/or colony formation in human and mouse endometrial, colon, thyroid and esophageal cancer cell lines. CONCLUSIONS Our data suggest that irisin, in physiological and high physiological/pharmacological concentrations, has no in vitro effect on cell proliferation and malignant potential of obesity-related cancer cell lines. Future work is needed to determine the regulation of irisin levels and any physiological effects it may have on obesity-related cancers in vivo in animals and humans.
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Affiliation(s)
- Hyun-Seuk Moon
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
| | - Christos S Mantzoros
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA; Section of Endocrinology, Boston VA Healthcare System, Harvard Medical School, Boston, MA 02130, USA
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Wang T, Ning G, Bloomgarden Z. Diabetes and cancer relationships. J Diabetes 2013; 5:378-90. [PMID: 23574745 DOI: 10.1111/1753-0407.12057] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/10/2013] [Accepted: 03/24/2013] [Indexed: 12/29/2022] Open
Abstract
Diabetes and cancer are both heterogeneous and multifactorial diseases with tremendous impact on health worldwide. Epidemiologic evidence suggests that certain malignancies may be associated with diabetes, as well as with diabetes risk factors and, perhaps, with certain diabetes treatments. Numerous biological mechanisms could account for these relationships. Insulin-like growth factor (IGF)-1, IGF-2, IGF-1 receptors, insulin, and the insulin receptor play roles in the development and progression of cancers. Although evidence from randomized controlled trials does not support or refute associations of diabetes and its treatments with either increased or reduced risk of cancer incidence or prognosis, consideration of malignancy incidence rates and the magnitude of the trials that would be required to address these issues explains why such studies may not be readily undertaken.
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Affiliation(s)
- Tiange Wang
- Key Laboratory for Endocrine and Metabolic Diseases of Ministry of Health, Shanghai, China; Shanghai Clinical Center for Endocrine and Metabolic Diseases, Rui-Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; E-Institute of Shanghai Universities, Shanghai, China
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Hong JL, Meier CR, Sandler RS, Jick SS, Stürmer T. Risk of colorectal cancer after initiation of orlistat: matched cohort study. BMJ 2013; 347:f5039. [PMID: 23982291 PMCID: PMC3754767 DOI: 10.1136/bmj.f5039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE To examine the risk of colorectal cancer after orlistat initiation in the UK population. DESIGN Retrospective matched cohort study. SETTING Data from the UK Clinical Practice Research Datalink from September 1998 to December 2008. PARTICIPANTS 33,625 adults aged 18 years or over who started treatment with orlistat; each orlistat initiator was matched to up to five non-initiators (n=160,347) on age, sex, body mass index, and calendar time. MAIN OUTCOME MEASURES Associations between orlistat initiation and the risk of colorectal cancer, assessed by calculating hazard ratios with propensity score adjusted Cox proportional hazard models. RESULTS Of 193,972 patients with a median age of 47 (interquartile range 37-57) years, 77% were women and approximately 90% were obese (body mass index ≥ 30). Orlistat initiators were more likely to have a previous history of diabetes or hypertension and to receive prescriptions for anti-diabetes drugs, statins, and aspirin compared with non-initiators. In the intention to treat analysis, 57 colorectal cancer events were identified among orlistat initiators and 246 among non-initiators, with median follow-up times of 2.96 and 2.86 years, respectively. The calculated incidence rate of colorectal cancer per 100,000 person years was 53 (95% confidence interval 41 to 69) for orlistat initiators and 50 (44 to 57) for non-initiators. Orlistat initiation was not associated with a higher risk of colorectal cancer (adjusted hazard ratio 1.11, 95% confidence interval 0.84 to 1.47). Findings were robust in the as treated analyses and in patients who were aged 50 years or over, were morbidly obese, or had a history of diabetes. CONCLUSIONS This study found no evidence of an increased risk of colorectal cancer after the initiation of orlistat. It is limited by the relatively short follow-up time, and the possibility of adverse effects of long term orlistat use on risk of colorectal cancer cannot be excluded.
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Affiliation(s)
- Jin-Liern Hong
- Department of Epidemiology, UNC Gillings School of Global Public Health, University of North Carolina at Chapel Hill, McGavran-Greenberg, CB # 7435, Chapel Hill, NC 27599-7435, USA. email.unc.edu
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Postmenopausal breast cancer, androgens, and aromatase inhibitors. Breast Cancer Res Treat 2013; 139:1-11. [PMID: 23572296 DOI: 10.1007/s10549-013-2505-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 03/25/2013] [Indexed: 02/06/2023]
Abstract
Recent data can help to better define the long debated relationship between androgens and breast cancer (BC) after menopause. We reviewed the available literature data on: the origin of androgens after menopause, the association between circulating androgens and BC incidence and recurrence, the relationship between circulating and intratumoral hormones, the prognostic significance of the presence of androgen receptors (ARs) in the different BC subtypes, the androgen effect on BC cell lines, and the relationship between androgens and aromatase inhibitors. Epidemiological, clinical, and preclinical data on the role of androgens and of ARs on estrogen receptor (ER)-negative BC are somewhat controversial. However, most preclinical studies suggest that activated ARs, when present, have a proliferative effect, particularly in HER2 expressing cell lines, due to the cross-talk between AR and HER2 pathways. As regards ER-positive BC, epidemiological studies associate androgen levels with increased incidence and risk of recurrences, whilst clinical studies associate the AR positivity with a better prognosis. Preclinical studies suggest that the action of androgens is bidirectional: mainly proliferative, because circulating androgens are the precursors of estrogens, but also anti-proliferative, because AR activation restrains ER activity. The relative increase of androgenic action that follows the blocking of androgen aromatization into estrogens by aromatase inhibitors (AIs), could contribute to their therapeutic efficacy in AR-positive cases. Available data, although defining a complex picture, suggest that circulating androgen levels are clinically relevant, particularly when AIs are used.
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