ASMBS position statement on the relationship between obesity and cancer, and the role of bariatric surgery: risk, timing of treatment, effects on disease biology, and qualification for surgery
2020; Elsevier BV; Volume: 16; Issue: 6 Linguagem: Inglês
10.1016/j.soard.2020.03.019
ISSN1878-7533
AutoresSaber Ghiassi, Maher El Chaar, Essa M. Aleassa, Fady Moustarah, Sofiane El Djouzi, T. Javier Birriel, Ann M. Rogers,
Tópico(s)Colorectal Cancer Screening and Detection
ResumoThe following position statement is issued by the American Society for Metabolic and Bariatric Surgery in response to numerous inquiries made to the Society by patients, physicians, Society members, hospitals, health insurance payors, the media, and others, regarding the relationship between obesity and cancer. This includes the increased incidence of cancer in patients with obesity, how obesity can impact conventional cancer screening, recommended cancer screening before bariatric surgery, the beneficial impact of weight loss not only on future cancer risk but on prolonged survivorship after cancer treatment, the timing of cancer treatment related to bariatric treatment in specific patients, and whether patients with active cancers may, in fact, be considered for bariatric surgery despite older guidelines to the contrary. This statement will also discuss ethical issues related to patients who decline cancer screening before bariatric surgery. In this statement, a summary of current, published, peer-reviewed scientific evidence, and expert opinion is presented. The intent of issuing such a statement is to provide available objective information about these topics. The statement is not intended as, and should not be construed as, stating or establishing a local, regional, or national standard of care. The statement will be revised in the future as additional evidence becomes available. Increased fat mass—particularly visceral fat—has been associated with an elevated incidence of a number of malignancies including cancers of the breast, endometrium, cervix, prostate, thyroid, stomach, liver, kidney, pancreas, gallbladder, and some ovarian subtypes [1Does body weight affect cancer risk? [homepage on the Internet]. Atlanta: American Cancer Society; c2020 [updated 2018 Jan 4; cited 2020 Mar 13]. Available from: https://www.cancer.org/cancer/cancer-causes/diet-physical-activity/body-weight-and-cancer-risk/effects.html.Google Scholar, 2Bhaskaran K. Douglas I. Forbes H. dos-Santos-Silva I. Leon D.A. Smeeth L. Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5.24 million UK adults.Lancet. 2014; 384: 755-765Abstract Full Text Full Text PDF PubMed Scopus (981) Google Scholar, 3Renehan A.G. Tyson M. Egger M. Heller R.F. Zwahlen M. Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies.Lancet. 2008; 371: 569-578Abstract Full Text Full Text PDF PubMed Scopus (3682) Google Scholar]. Overweight and obesity are also found to be associated with esophageal adenocarcinoma, colon and rectal cancer, multiple myeloma, non-Hodgkin's lymphoma, and more recently melanoma [[2]Bhaskaran K. Douglas I. Forbes H. dos-Santos-Silva I. Leon D.A. Smeeth L. Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5.24 million UK adults.Lancet. 2014; 384: 755-765Abstract Full Text Full Text PDF PubMed Scopus (981) Google Scholar,[3]Renehan A.G. Tyson M. Egger M. Heller R.F. Zwahlen M. Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies.Lancet. 2008; 371: 569-578Abstract Full Text Full Text PDF PubMed Scopus (3682) Google Scholar]. GLOBOCAN, a comprehensive cancer surveillance database managed by the International Association of Cancer Registries, estimated in 2012 approximately 28,000 (3.5%) new cases of cancer in men and 72,000 (9.5%) in women were because of obesity as identified by elevated body mass index (BMI) [[4]Arnold M. Pandeya N. Byrnes G. et al.Global burden of cancer attributable to high body-mass index in 2012: a population-based study.Lancet Oncol. 2015; 16: 36-46Abstract Full Text Full Text PDF PubMed Scopus (595) Google Scholar]. This incidence varied by cancer type, but elevated weight contributed to as many as 44% of esophageal cancers in men and 54% of gallbladder cancers in women. A large prospective cohort study of >500,000 U.S. adults estimated that overweight and obesity contributed to 14% of all cancer deaths in men and 20% in women [[5]Adams K.F. Schatzkin A. Harris T.B. et al.Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years old.N Engl J Med. 2006; 355: 763-778Crossref PubMed Scopus (1711) Google Scholar]. Of further concern is the finding that several cancers traditionally found in patients >50 years of age are now being diagnosed with increasing frequency in younger age groups. This includes breast, colorectal, kidney, endometrial, thyroid, liver, gastric, meningioma, ovarian, and esophageal adenocarcinoma [[6]Berger N.A. Young adult cancer: influence of the obesity pandemic.Obesity. 2018; 26: 641-650Crossref PubMed Scopus (44) Google Scholar]. Obesity promotes the development of cancer through multiple mechanisms, including proinflammatory cytokines, elevated amounts of reactive oxygen species and growth factors, increased conversion of androgens to estrogens, reduced growth-controlling adipokines, changes in gut microbiota with an increase in tumor-promoting species, as well as mechanical effects, such as gastroesophageal reflux, which may increase risk for esophageal adenocarcinoma. It is likely the shift of other malignancies to younger populations will continue in the future as obesity continues to increase [[6]Berger N.A. Young adult cancer: influence of the obesity pandemic.Obesity. 2018; 26: 641-650Crossref PubMed Scopus (44) Google Scholar]. An analysis of population-based cancer registries in the United States from 1995 to 2014, examining 14,672,409 cancer cases, showed the incidence of 6 obesity-related cancers (multiple myeloma, colorectal, endometrial, gallbladder, kidney, and pancreas) increased significantly in young adults (25–49 yr), with a steeper rise in successively younger generations. While the incidence of some cancers (including smoking- and HIV-associated cancers) is decreasing in younger patients, the dramatic rise in the prevalence of overweight and obesity in young adults is expected to negate these gains and increase the future burden of cancer overall [[7]Sung H. Siegel R.L. Rosenberg P.S. Jemal A. Emerging cancer trends among young adults in the USA: analysis of a population-based cancer registry.Lancet Public Health. 2019; 4: e137-e147Abstract Full Text Full Text PDF PubMed Scopus (245) Google Scholar]. In a study from Canada, where the average reported wait time from referral of a patient with obesity to bariatric surgery was 5.2 years [[8]Christou N.V. Efthimiou E. Bariatric surgery waiting times in Canada.Can J Surg. 2009; 52: 229-234PubMed Google Scholar], the most common cause of death in patients awaiting bariatric surgery was cancer, and the mortality rate in this wait-listed group was 1.57%; 3 times higher than the nationally reported rate of .49% in the general population at the time [[9]Lakoff J.M. Ellsmere J. Random T. Causes of death in patients awaiting bariatric surgery.Can J Surg. 2015; 58: 15-18Crossref PubMed Scopus (16) Google Scholar]. It is clear from these, and many other studies, there is a relationship between overweight and obesity, and certain forms of cancer. All the biological mechanisms for this relationship are still under intense study. As background for this position statement, we will examine the complex clinical interrelationship between obesity and cancer, including the impact on screening and treatment, weight loss through bariatric surgery, and its effects on cancer prevalence and outcomes, the timing of bariatric versus cancer surgery, and other related questions. Cancer is a major health problem and one of the leading causes of mortality, accounting for up to 25% of deaths in the United States [[10]Siegel R.L. Miller K.D. Jemal A. Cancer statistics, 2015.CA Cancer J Clin. 2015; 65: 5-29Crossref PubMed Scopus (11503) Google Scholar]. The early detection of presymptomatic cancer through screening is a key step in reducing cancer-associated morbidity and mortality. However, obesity may decrease the frequency and quality of cancer screening, and may therefore contribute to increased cancer-related mortality in patients with obesity. Although individuals with obesity may have frequent medical visits for obesity-related co-morbidities, healthcare providers, including bariatric surgeons, should not assume these individuals are obtaining appropriate cancer screening, as this population may face challenges that reduce the occurrence of such screening. A history of having undergone bariatric surgery has been found to be associated with decreased incidence of breast cancer and its associated mortality [11Aravani A. Downing A. Thomas J.D. Lagergren J. Morris E.J.A. Hull M.A. Obesity surgery and risk of colorectal and other obesity-related cancers: an English population-based cohort study.Cancer Epidemiol. 2018; 53: 99-104Crossref PubMed Scopus (41) Google Scholar, 12Christou N.V. Lieberman M. Sampalis F. Sampalis J.S. Bariatric surgery reduces cancer risk in morbidly obese patients.Surg Obes Relat Dis. 2008; 4: 691-695Abstract Full Text Full Text PDF PubMed Scopus (180) Google Scholar, 13Adams T.D. Hunt S.C. Cancer and obesity: effect of bariatric surgery.World J Surg. 2009; 33: 2028-2033Crossref PubMed Scopus (49) Google Scholar, 14Gusenoff J.A. Koltz P.F. O'Malley W.J. Messing S. Chen R. Langstein H.N. Breast cancer and bariatric surgery: temporal relationships of diagnosis, treatment, and reconstruction.Plast Reconstr Surg. 2009; 124: 1025-1032Crossref PubMed Scopus (10) Google Scholar]. On the other hand, women with obesity are at higher risk for morbidity and mortality from postmenopausal breast cancer but are less likely to undergo screening mammography. In a systematic review of studies examining the relationship between weight and mammography, Maruthur et al. [[15]Maruthur N.M. Bolen S. Brancati F.L. Clark J.M. Obesity and mammography: a systematic review and meta-analysis.J Gen Intern Med. 2009; 24: 665-677Crossref PubMed Scopus (106) Google Scholar] found increasing weight was related to lower likelihood of undergoing mammography consistently across the studies. Women with a BMI ≥40 kg/m2 were significantly less likely than those of lower BMI (combined odds ratio [OR] = .79, 95% confidence interval [CI]: .068–.92) to have undergone mammography in the prior 2 years. This relationship appeared stronger in white women. A lower screening rate may partly account for increased breast cancer mortality in women with severe obesity [[16]Cohn S.S. Palmieri R.T. Nyante S.J. et al.A review: obesity and screening for breast, cervical, and colorectal cancer in women.Cancer. 2008; 112: 1892-1904Crossref PubMed Scopus (120) Google Scholar]. In a study designed to identify patient barriers to mammography, Feldstein et al. [[17]Feldstein A.C. Perrin N. Rosales A.G. Schneider J. Rix M.M. Glasgow R.E. Patient barriers to mammography identified during a reminder program.J Womens Health. 2011; 20: 421-428Crossref Scopus (19) Google Scholar] found obesity was associated with lower mammogram completion rates (OR = .67, P < .0001). Of note, women with obesity in this cohort were much more likely to report "too much pain" from mammograms [[17]Feldstein A.C. Perrin N. Rosales A.G. Schneider J. Rix M.M. Glasgow R.E. Patient barriers to mammography identified during a reminder program.J Womens Health. 2011; 20: 421-428Crossref Scopus (19) Google Scholar]. Obesity and breast density may also impact the sensitivity and specificity of mammography. In an analysis of 100,622 screening mammograms, the risk of false-positive results was increased by 20% in women with obesity compared with underweight or healthy weight women. The authors concluded that weight loss may improve the tolerance for and accuracy of mammography [[18]Elmore J.G. Carney P.A. Abraham L.A. et al.The association between obesity and screening mammography accuracy.Arch Intern Med. 2004; 164: 1140-1147Crossref PubMed Scopus (79) Google Scholar]. As with breast cancer, women with obesity undergo screening for cervical cancer less frequently. Most studies on cervical cancer screening found a negative association between increasing weight and screening, and this negative association was again most consistent in white women [[16]Cohn S.S. Palmieri R.T. Nyante S.J. et al.A review: obesity and screening for breast, cervical, and colorectal cancer in women.Cancer. 2008; 112: 1892-1904Crossref PubMed Scopus (120) Google Scholar,[19]Fagan H.B. Wender R. Myers R.E. Petrelli N. Obesity and cancer screening according to race and gender.J Obes. 2011; 2011: 1-10Google Scholar]. Data from the National Cancer Institute's 2005 Health Information National Trends Survey showed women aged 25 to 64 years with obesity were significantly less likely to adhere to recommended cervical cancer screening guidelines (OR = .3 for class III obesity, 95%CI: .15–.59) [[20]Nelson W. Moser R.P. Gaffey A. Waldron W. Adherence to cervical cancer screening guidelines for U.S. women aged 25-64: data from the 2005 Health Information National Trends Survey (HINTS).J Womens Health (Larchmt). 2009; 18: 1759-1768Crossref PubMed Scopus (96) Google Scholar]. In a meta-analysis of studies evaluating the relationship between weight and Papanicolaou testing in the United States, Maruthur et al. [[21]Maruthur N.M. Bolen S. Brancati F.L. Clark J.M. The association of obesity and cervical cancer screening: a systematic review and meta-analysis.Obesity. 2009; 17: 375-381Crossref PubMed Scopus (116) Google Scholar] reported an inverse relationship between cervical cancer screening and obesity. Compared with women with a healthy BMI, the combined OR for Papanicolaou testing was .75 (95%CI: .64–.88) for class III obesity. In this systematic review, 3 of 4 studies that considered race as a factor found this inverse relationship held true for white women, but no study found this for black women. The authors concluded lower screening rates may partly explain the higher cervical cancer mortality in white women with obesity [[21]Maruthur N.M. Bolen S. Brancati F.L. Clark J.M. The association of obesity and cervical cancer screening: a systematic review and meta-analysis.Obesity. 2009; 17: 375-381Crossref PubMed Scopus (116) Google Scholar]. Obesity also increases the risk for colorectal cancer (CRC) and may have a negative impact on CRC screening. The relationship between weight and CRC screening in men is inconsistent, while there is a trend toward lower CRC screening in women of higher weight [[22]Seibert R.G. Hanchate A.D. Berz J.P. Schroy III, P.C. National disparities in colorectal cancer screening among obese adults.Am J Prev Med. 2017; 53: e41-e49Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar]. The data for 8550 respondents aged 50 to 75 years in the 2010 National Health Interview Survey showed men with a BMI ≥40 kg/m2 were significantly less likely to adhere to screening guidelines compared with men of healthy weight (adjusted OR = .35, 95%CI: .17–.75); were less likely to have had an endoscopic examination (adjusted OR = .37, 95% CI: .18–.79); and had a trend toward lower fecal occult blood test use (adjusted OR = .42, 95% CI: .14–1.27) [[23]Al Hadad M. Dehni N. Alakhras A. Ziaei Y. Turrin N.P. Nimeri A. Screening colonoscopy in the initial workup of bariatric surgery patients: guidelines are needed.Surg Endosc. 2014; 28: 1607-1612Crossref PubMed Scopus (5) Google Scholar]. Men with obesity were more likely to state "lack of physician recommendation" as a reason for nonadherence to screening (29.7% obese class III versus 15.4% nonobese, P = .04). The odds of adherence and use of different screening modalities for women were similar across all BMIs, yet for nonadherent women, more women with class III obesity reported "pain" and "embarrassment" as the reasons for nonadherence to screening compared to women of healthy weight (11.6% versus 2.6%, P = .002) [[22]Seibert R.G. Hanchate A.D. Berz J.P. Schroy III, P.C. National disparities in colorectal cancer screening among obese adults.Am J Prev Med. 2017; 53: e41-e49Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar]. When patients are screened, adenomatous polyps are detected at a higher rate as BMI increases [[23]Al Hadad M. Dehni N. Alakhras A. Ziaei Y. Turrin N.P. Nimeri A. Screening colonoscopy in the initial workup of bariatric surgery patients: guidelines are needed.Surg Endosc. 2014; 28: 1607-1612Crossref PubMed Scopus (5) Google Scholar]. Ferrante et al. [[24]Ferrante J.M. Ohman-Strickland P. Hudson S.V. Hahn K.A. Scott J.G. Crabtree B.F. Colorectal cancer screening among obese versus non-obese patients in primary care practices.Cancer Detect Prev. 2006; 30: 459-465Abstract Full Text Full Text PDF PubMed Scopus (77) Google Scholar] reviewed the rate of CRC screening in 22 suburban primary care practices. Among 1297 patients age ≥50 years, 39% of patients had obesity and 29% received CRC screening. After controlling for age, sex, total number of co-morbidities, number of visits in the past 2 years, and number of years in the practice, patients with obesity had 25% lower odds of being screened for CRC compared with patients without obesity (OR = .75, 95% CI: .62–.91, P = .004). The relationship between obesity and CRC screening was similar for men and women [[24]Ferrante J.M. Ohman-Strickland P. Hudson S.V. Hahn K.A. Scott J.G. Crabtree B.F. Colorectal cancer screening among obese versus non-obese patients in primary care practices.Cancer Detect Prev. 2006; 30: 459-465Abstract Full Text Full Text PDF PubMed Scopus (77) Google Scholar]. Using the Centers for Disease Control Behavioral Risk Factor Surveillance System, Rosen and Schneider [[25]Rosen A.B. Schneider E.C. Colorectal cancer screening disparities related to obesity and gender.J Gen Intern Med. 2004; 19: 332-338Crossref PubMed Scopus (117) Google Scholar] examined the rates of self-reported CRC screening with fecal occult blood testing within the past year or endoscopic screening (sigmoidoscopy or colonoscopy) within the past 5 years among 52,886 respondents. After statistical adjustment for potential confounders, women with severe obesity were less likely than women of healthy weight to undergo CRC screening (adjusted rate difference −5.6%; 95% CI: −8.5 to −2.6). Screening rates for men in different weight groups did not differ significantly [[25]Rosen A.B. Schneider E.C. Colorectal cancer screening disparities related to obesity and gender.J Gen Intern Med. 2004; 19: 332-338Crossref PubMed Scopus (117) Google Scholar]. Obesity is very strongly associated with the development of endometrial cancer, in a dose-response relationship with BMI. Approximately 57% of endometrial cancers in the United States are thought to be attributable to overweight and obesity [[26]Onstad M.A. Schmandt R.E. Lu K.H. Addressing the role of obesity in endometrial cancer risk, prevention, and treatment.J Clin Oncol. 2016; 34: 4225-4230Crossref PubMed Scopus (225) Google Scholar]. Given the adverse effect of obesity on the prevalence and mortality of cervical and other cancers, it is important to emphasize screening efforts, particularly for women. Bariatric treatment programs, with a mostly female patient population, could be in a position to recommend appropriate screening in selected patients before their undertaking elective surgery. In a survey sent to 1503 U.S. bariatric surgeons, 80% of the 263 respondents obtained gynecologic histories, but 56% and 49% did not require Papanicolaou testing or mammograms, respectively, before bariatric surgery. Only 21% of respondents had ever referred a patient for endometrial evaluation, and 20% of surgeons did not consistently counsel their patients about increased cancer risks due to obesity [[27]Winfree L.E. Henretta M.S. Hallowell P.T. Modesitt S.C. Pre-operative gynecologic evaluation of bariatric surgery patients: improving cancer detection in a high-risk population.J Am Coll Surg. 2010; 211: 256-262Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar]. Bariatric surgeons correctly identified postmenopausal bleeding (99%), obesity (97%), irregular or heavy periods (69%), hereditary nonpolyposis colorectal cancer (21%), infertility (20.2%), diabetes (14.1%), and hypertension (4.9%) as signs and risk factors of endometrial cancer [[27]Winfree L.E. Henretta M.S. Hallowell P.T. Modesitt S.C. Pre-operative gynecologic evaluation of bariatric surgery patients: improving cancer detection in a high-risk population.J Am Coll Surg. 2010; 211: 256-262Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar]. Obesity may be associated with reduced risk of low-grade nonaggressive prostate cancer but increased risk for more aggressive disease [[28]Thomas II, J.A. Freedland S.J. Obesity and prostate cancer: collateral damage in the battle of the bulge.Front Biosci. 2011; 3: 594-605Google Scholar] and there is emerging evidence of periprostatic white adipose tissue inflammation as a driver of higher Gleason Score [[29]Gucalp A. Iyengar N.M. Zhou X.K. et al.Periprostatic adipose inflammation is associated with high-grade prostate cancer.Prostate Cancer Prostatic Dis. 2017; 20: 418-423Crossref PubMed Scopus (48) Google Scholar]. Interestingly, studies suggest men with obesity are more likely than individuals of healthy weight to undergo prostate-specific antigen testing [[30]Scales C.D. Curtis L.H. Norris R.D. Schulman K.A. Dahm P. Moul J.W. Relationship between body mass index and prostate cancer screening in the United States.J Urol. 2007; 177: 493-498Crossref PubMed Scopus (27) Google Scholar,[31]Yancy W.S. McDuffie J.R. Stechuchak K.M. et al.Obesity and receipt of clinical preventive services in veterans.Obesity. 2010; 18: 1827-1835Crossref PubMed Scopus (20) Google Scholar]; it is not clear if this is related to a decreased likelihood of having had an actual prostate examination. Using the 2001 Centers for Disease Control Behavioral Risk Factor Surveillance System data for men aged ≥50 years, Fontaine et al. [[32]Fontaine K.R. Heo M. Allison D.B. Obesity and prostate cancer screening in the USA.Public Health. 2005; 119: 694-698Crossref PubMed Scopus (37) Google Scholar] reported that obesity was associated with increased OR for obtaining prostate-specific antigen test (class I obesity OR = 1.26, 95%CI: 1.06–1.36; and class II obesity OR = 1.14, 95%CI: 1.02–1.26) after adjusting for age, race, smoking, education, employment, income, and health insurance status [[32]Fontaine K.R. Heo M. Allison D.B. Obesity and prostate cancer screening in the USA.Public Health. 2005; 119: 694-698Crossref PubMed Scopus (37) Google Scholar]. Weight loss in persons with obesity reduces cancer risk. Multiple studies have shown bariatric surgery results in a significant decrease in cancer risk and cancer mortality in patients with obesity, notably in women [33Tee M.C. Cao Y. Warnock G.L. Hu F.B. Chavarro J.E. Effect of bariatric surgery on oncologic outcomes: a systematic review and meta-analysis.Surg Endosc. 2013; 27: 4449-4456Crossref PubMed Scopus (73) Google Scholar, 34Adams T.D. Mehta T.S. Davidson L.E. Hunt S.C. All-cause and cause-specific mortality associated with bariatric surgery: a review.Curr Atheroscler Rep. 2015; 17: 74Crossref PubMed Scopus (52) Google Scholar, 35Sjöström L. Gummesson A. Sjöström C.D. et al.Effects of bariatric surgery on cancer incidence in obese patients in Sweden (Swedish Obese Subjects Study): a prospective, controlled intervention trial.Lancet Oncol. 2009; 10: 653-662Abstract Full Text Full Text PDF PubMed Scopus (547) Google Scholar, 36Anveden Å. Taube M. Peltonen M. et al.Long-term incidence of female-specific cancer after bariatric surgery or usual care in the Swedish Obese Subjects Study.Gynecol Oncol. 2017; 145: 224-229Abstract Full Text Full Text PDF PubMed Scopus (77) Google Scholar, 37Zhang K. Luo Y. Dai H. Deng Z. Effects of bariatric surgery on cancer risk: evidence from meta-analysis.Obes Surg. 2020; 30: 1265-1272Crossref PubMed Scopus (30) Google Scholar], leading some authors to suggest treating metabolic dysfunction may be the next frontier in cancer prevention [[38]Argenta P.A. Attacking obesity-related diseases at the source - is bariatric surgery the next wave in cancer prevention?.Gynecol Oncol. 2017; 145: 219-220Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar]. The reduction in the incidence of cancer after bariatric surgery was found to be related to the weight loss itself and not to the effect of simply having undergone surgery. In a recent study, Schauer et al. [[39]Schauer D.P. Feigelson H.S. Koebnick C. et al.Association between weight loss and the risk of cancer after bariatric surgery.Obesity (Silver Spring). 2017; 25: S52-S57Crossref PubMed Scopus (45) Google Scholar] found, "in adjusted models, the association between bariatric surgery and cancer risk was explained by weight loss and was not independently associated with surgery." Baseline obesity has been linked to poor prognosis in breast cancer patients [[40]Protani M. Coory M. Martin J.H. Effect of obesity on survival of women with breast cancer: systematic review and meta-analysis.Breast Cancer Res Treat. 2010; 123: 627-635Crossref PubMed Scopus (685) Google Scholar]. Furthermore, weight gain after initial cancer treatment has been associated with disease recurrence and cancer death in several types of cancer, such as breast [[41]Majed B. Moreau T. Senouci K. Salmon R.J. Fourquet A. Asselain B. Is obesity an independent prognosis factor in woman breast cancer?.Breast Cancer Res Treat. 2008; 111: 329-342Crossref PubMed Scopus (186) Google Scholar], prostate [[42]Cao Y. Ma J. Body mass index, prostate cancer-specific mortality, and biochemical recurrence: a systematic review and meta-analysis.Cancer Prev Res (Phila). 2011; 4: 486-501Crossref PubMed Scopus (336) Google Scholar], and CRC [[43]Sinicrope F.A. Foster N.R. Sargent D.J. O'Connell M.J. Rankin C. Obesity is an independent prognostic variable in colon cancer survivors.Clin Cancer Res. 2010; 16: 1884-1893Crossref PubMed Scopus (180) Google Scholar]. However, prior bariatric surgery has also been shown to improve the outcomes of CRC patients in the perioperative period [[44]Hussan H. Stanich P.P. Gray D.M. et al.Prior bariatric surgery is linked to improved colorectal cancer surgery outcomes and costs: a propensity-matched analysis.Obes Surg. 2017; 27: 1047-1055Crossref PubMed Scopus (11) Google Scholar]. Winder et al. [[45]Winder A.A. Kularatna M. MacCormick A.D. Does bariatric surgery affect the incidence of breast cancer development? A systematic review.Obes Surg. 2017; 27: 3014-3020Crossref PubMed Scopus (24) Google Scholar] concluded bariatric surgery results in a decrease in the incidence of endometrial cancer. Linkov et al. [[46]Linkov F. Elishaev E. Gloyeske N. et al.Bariatric surgery-induced weight loss changes immune markers in the endometrium of morbidly obese women.Surg Obes Relat Dis. 2014; 10: 921-926Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar] have also shown bariatric surgery can result in changes in hormone receptor markers on endometrial cells, which could become the target of novel therapies for endometrial cancer. It is important to distinguish the impact of intentional versus unintentional weight loss on cancer survivorship when assessing the literature. Intentional weight loss in the general population is linked to increased survival while unintentional weight loss has been associated with decreased survival. Most studies assessing weight loss in cancer survivors have been conducted in breast cancer patients. A systematic review [[47]Jackson S.E. Heinrich M. Beeken R.J. Wardle J. Weight loss and mortality in overweight and obese cancer survivors: a systematic review.PLoS One. 2017; 12e0169173Crossref PubMed Scopus (27) Google Scholar] assessing the effect of weight loss in breast cancer survivors managed to identify only 5 observational studies, all with lower-level evidence, but all of which suggested significant weight loss or gain after treatment could lead to an increased risk of death [48Caan B.J. Kwan M.L. Shu X.O. et al.Weight change and survival after breast cancer in the after breast cancer pooling project.Cancer Epidemiol Biomarkers Prev. 2012; 21: 1260-1271Crossref PubMed Scopus (100) Google Scholar, 49Bradshaw P.T. Ibrahim J.G. Stevens J. et al.Postdiagnosis change in bodyweight and survival after breast cancer diagnosis.Epidemiology. 2012; 23: 320-327Crossref PubMed Scopus (77) Google Scholar, 50Chen X. Lu W. Zheng W. et al.Obesity and weight change in relation to breast cancer survival.Breast Cancer Res Treat. 2010; 122: 823-833Crossref PubMed Scopus (128) Google Scholar, 51Caan B.J. Kwan M.L. Hartzell G. et al.Pre-diagnosis body mass index, post-diagnosis weight change, and prognosis among women with early stage breast cancer.Cancer Causes Control. 2008; 19: 1319-1328Crossref PubMed Scopus (186) Google Scholar, 52Kroenke C.H. Chen W.Y. Rosner B. Holmes M.D. Weight, weight gain, and survival after breast cancer diagnosis.J Clin Oncol. 2005; 23: 1370-1378Crossref PubMed Scopus (521) Google Scholar]. None of the included studies limited their study sample to posttreatment breast cancer survivors nor did they differentiate between the stages of disease or intentional versus unintentional weight change; unfortunately, this makes drawing robust conclusions difficult and the authors suggest only attempts to maintain stable weight may improve survival in cancer patients. The following are ongoing trials assessing the effect of intentional weight loss on cancer survival and recurrence, again mainly in breast cancer patients: the Moving Forward trial [[53]Stolley M.R. Sharp L.K. Fantuzzi G. et al.Study design and protocol for moving forward: a weight loss intervention trial for African-American breast cancer survivors.BMC Cancer. 2015; 15: 1018Crossref PubMed
Referência(s)