Correspondence Re: Risks of Colorectal and Other Cancers After Endometrial Cancer for Women With Lynch Syndrome
Ahmet Afsin Oktay S. Neslihan Alpay Ibrahim Halil Sahin
jnci.oxfordjournals.org
1. Win AK, Lindor NM, Winship I, et al. Risks of colorectal and other cancers after endome trial cancer for women with Lynch syndrome. J Natl Cancer Inst. 2013;105(4):274–279. 2. Moghaddam AA, Woodward M, Huxley R. Obesity and risk of colorectal cancer: a meta-analysis of 31 studies with 70,000 events. Cancer Epidemiol Biomarker Prev. 2007;16(12):2533–2547. 3. Calle EE, Kaaks R. Overweight, obesity and cancer: epidemiological evidence and proposed mechanisms. Nat Rev Cancer. 2004;4(8):579–591. 4. Singh H, Nugent Z, Demers A, et al. Risk of colorectal cancer after diagnosis of endome trial cancer: a population-based study. J Clin Oncol. 2013;31(16):2010–2015. 5. Goodman MT, Hankin JH, Wilkens LR, et al. Diet, body size, physical activity, and the risk of endometrial cancer. Cancer Res. 1997;57(22):5077–5085. 6. Trock B, Lanza E, Greenwald P. Dietary fiber, vegetables, and colon cancer: critical review and meta-analyses of the epidemiologic evidence. J Natl Cancer Inst. 1990;82(8): 650–661.
Note All authors contributed equally. The authors declare no conflicts of interest. Affiliations of authors: Department of Internal Medicine, Saint Francis Hospital, Evanston, IL (AAO); Department of Experimental Therapeutics (SNA) and Department of Gastrointestinal Medical Oncology (IHS), University of Texas MD Anderson Cancer Center, Houston, TX. Correspondence to: Ibrahim Halil Sahin, MD, Department of Gastrointestinal Medical Oncology, Unit 426, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030 (e-mail: [email protected]). DOI:10.1093/jnci/djt307 Advance Access publication October 29, 2013 ©The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: [email protected].
Response Oktay et al. raise two issues related to our recent study on risks of colorectal and other cancers after endometrial cancer for women with Lynch syndrome (1). Oktay et al. sug gest that obesity and/or diet might have independently contributed to the increased risk of colorectal cancer we observed, given
they are risk factors for endometrial and colorectal cancer for women in the general population (ie, they are potential confound ers). We argue that these lifestyle factors are unlikely to have an impact on our estimation of cancer risks. First, one of our measures of association was a comparison between inci dences of cancers after endometrial cancer for women with Lynch syndrome and inci dences of cancers after endometrial cancer for women from the general population [see Table 3; SIR2 for colorectal cancer = 36.3, 95% confidence interval = 25.8 to 49.6 (1)]. For this comparison, the only differ ence between the two groups of women was whether the women carried a germline mutation in a mismatch repair gene, which is not associated with body mass index or diet, and therefore this measure of association cannot be due to confounding with obesity or diet. Second, in contrast with women from the general population, we have reported in a previous study that obesity is not associ ated with an increased risk of endometrial cancer for women with Lynch syndrome (2). Third, in our study of women with Lynch syndrome and history of endometrial cancer, there was no difference in body mass index at age 20 years between those who did and did not develop colorectal cancer (mean = 22, standard deviation [SD] = 3.7 vs mean = 22, SD = 4.0 kg/m2; P = .61). Similarly there was no difference in recent body mass index (within 2 years before interview) between those who did and did not develop colorectal cancer (mean = 27, SD = 6.0 vs mean = 27, SD = 5.9 kg/m2; P = .51). There was also no evidence of difference in intakes of fruit, vegetables, and red meat between those with and without colorectal cancer (data not shown). Oktay et al. also claim, “[W]e don’t know whether the risk of those cancers in patients with a history of endometrial can cer and Lynch syndrome is also higher than the risk in patients with Lynch syndrome but no history of endometrial cancer.” In fact, we have examined and reported on this by comparing cancer risks for women who had Lynch syndrome and history of endometrial cancer with cancer risks for women who had Lynch syndrome but no prior history of any cancer (3) [See detail JNCI | Correspondence 1837
Downloaded from http://jnci.oxfordjournals.org/ at Belgorod State University on February 6, 2014
In a recent article in the Journal, Win and colleagues (1) demonstrated that the risk of colorectal cancer after endometrial can cer is statistically significantly increased in women with Lynch syndrome. The authors also reported a higher risk of kidney, renal pelvic, ureter, urinary bladder, and breast cancer in these patients. Although the results of their study expand our under standing of Lynch syndrome, we would like to note some additional factors that warrant discussion First, obesity is a risk factor for colorec tal cancer (2). Higher endometrial cancer incidence rates in the obese population have also been reported (3). Patients included in this study with a history of endometrial cancer might have also been obese, which would have substantially increased their risk of colorectal cancer. Another recent study revealed a higher risk of colorectal cancer in women with a history of endometrial can cer but not Lynch syndrome (4). Therefore, obesity might have independently affected the results of the study by Win and col leagues. Moreover, the dietary habits that increase the risk of endometrial cancer also increase the risk of colorectal cancer (5,6). However, the impact of diet on patient out comes was not assessed in this study. Finally, the authors reported an incre ased risk of the aforementioned cancers compared with the risk in the general pop ulation. However, we don’t know whether the risk of those cancers in patients with a history of endometrial cancer and Lynch syndrome is also higher than the risk in patients with Lynch syndrome but no his tory of endometrial cancer. Overall, to understand the risk of colo rectal cancer in women with previous endometrial cancer and Lynch syndrome, further prospective studies controlling for epidemiologic risk factors are warranted.
References
Ahmet Afsin Oktay S. Neslihan Alpay Ibrahim Halil Sahin
jnci.oxfordjournals.org
1. Win AK, Lindor NM, Winship I, et al. Risks of colorectal and other cancers after endome trial cancer for women with Lynch syndrome. J Natl Cancer Inst. 2013;105(4):274–279. 2. Moghaddam AA, Woodward M, Huxley R. Obesity and risk of colorectal cancer: a meta-analysis of 31 studies with 70,000 events. Cancer Epidemiol Biomarker Prev. 2007;16(12):2533–2547. 3. Calle EE, Kaaks R. Overweight, obesity and cancer: epidemiological evidence and proposed mechanisms. Nat Rev Cancer. 2004;4(8):579–591. 4. Singh H, Nugent Z, Demers A, et al. Risk of colorectal cancer after diagnosis of endome trial cancer: a population-based study. J Clin Oncol. 2013;31(16):2010–2015. 5. Goodman MT, Hankin JH, Wilkens LR, et al. Diet, body size, physical activity, and the risk of endometrial cancer. Cancer Res. 1997;57(22):5077–5085. 6. Trock B, Lanza E, Greenwald P. Dietary fiber, vegetables, and colon cancer: critical review and meta-analyses of the epidemiologic evidence. J Natl Cancer Inst. 1990;82(8): 650–661.
Note All authors contributed equally. The authors declare no conflicts of interest. Affiliations of authors: Department of Internal Medicine, Saint Francis Hospital, Evanston, IL (AAO); Department of Experimental Therapeutics (SNA) and Department of Gastrointestinal Medical Oncology (IHS), University of Texas MD Anderson Cancer Center, Houston, TX. Correspondence to: Ibrahim Halil Sahin, MD, Department of Gastrointestinal Medical Oncology, Unit 426, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030 (e-mail: [email protected]). DOI:10.1093/jnci/djt307 Advance Access publication October 29, 2013 ©The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: [email protected].
Response Oktay et al. raise two issues related to our recent study on risks of colorectal and other cancers after endometrial cancer for women with Lynch syndrome (1). Oktay et al. sug gest that obesity and/or diet might have independently contributed to the increased risk of colorectal cancer we observed, given
they are risk factors for endometrial and colorectal cancer for women in the general population (ie, they are potential confound ers). We argue that these lifestyle factors are unlikely to have an impact on our estimation of cancer risks. First, one of our measures of association was a comparison between inci dences of cancers after endometrial cancer for women with Lynch syndrome and inci dences of cancers after endometrial cancer for women from the general population [see Table 3; SIR2 for colorectal cancer = 36.3, 95% confidence interval = 25.8 to 49.6 (1)]. For this comparison, the only differ ence between the two groups of women was whether the women carried a germline mutation in a mismatch repair gene, which is not associated with body mass index or diet, and therefore this measure of association cannot be due to confounding with obesity or diet. Second, in contrast with women from the general population, we have reported in a previous study that obesity is not associ ated with an increased risk of endometrial cancer for women with Lynch syndrome (2). Third, in our study of women with Lynch syndrome and history of endometrial cancer, there was no difference in body mass index at age 20 years between those who did and did not develop colorectal cancer (mean = 22, standard deviation [SD] = 3.7 vs mean = 22, SD = 4.0 kg/m2; P = .61). Similarly there was no difference in recent body mass index (within 2 years before interview) between those who did and did not develop colorectal cancer (mean = 27, SD = 6.0 vs mean = 27, SD = 5.9 kg/m2; P = .51). There was also no evidence of difference in intakes of fruit, vegetables, and red meat between those with and without colorectal cancer (data not shown). Oktay et al. also claim, “[W]e don’t know whether the risk of those cancers in patients with a history of endometrial can cer and Lynch syndrome is also higher than the risk in patients with Lynch syndrome but no history of endometrial cancer.” In fact, we have examined and reported on this by comparing cancer risks for women who had Lynch syndrome and history of endometrial cancer with cancer risks for women who had Lynch syndrome but no prior history of any cancer (3) [See detail JNCI | Correspondence 1837
Downloaded from http://jnci.oxfordjournals.org/ at Belgorod State University on February 6, 2014
In a recent article in the Journal, Win and colleagues (1) demonstrated that the risk of colorectal cancer after endometrial can cer is statistically significantly increased in women with Lynch syndrome. The authors also reported a higher risk of kidney, renal pelvic, ureter, urinary bladder, and breast cancer in these patients. Although the results of their study expand our under standing of Lynch syndrome, we would like to note some additional factors that warrant discussion First, obesity is a risk factor for colorec tal cancer (2). Higher endometrial cancer incidence rates in the obese population have also been reported (3). Patients included in this study with a history of endometrial cancer might have also been obese, which would have substantially increased their risk of colorectal cancer. Another recent study revealed a higher risk of colorectal cancer in women with a history of endometrial can cer but not Lynch syndrome (4). Therefore, obesity might have independently affected the results of the study by Win and col leagues. Moreover, the dietary habits that increase the risk of endometrial cancer also increase the risk of colorectal cancer (5,6). However, the impact of diet on patient out comes was not assessed in this study. Finally, the authors reported an incre ased risk of the aforementioned cancers compared with the risk in the general pop ulation. However, we don’t know whether the risk of those cancers in patients with a history of endometrial cancer and Lynch syndrome is also higher than the risk in patients with Lynch syndrome but no his tory of endometrial cancer. Overall, to understand the risk of colo rectal cancer in women with previous endometrial cancer and Lynch syndrome, further prospective studies controlling for epidemiologic risk factors are warranted.
References
