IJC International Journal of Cancer
Red meat subtypes and colorectal cancer risk Nuri Faruk Aykan
Letter to the Editor
Department of Medical Oncology, Istanbul University, Institute of Oncology, Capa, Istanbul, Turkey
Dear Editor, I read with a great interest the manuscript of “Meat subtypes and their association with colorectal cancer: Systematic review and meta-analysis” reported by Prudence R. Carr and colleagues.1 I want to point out that I identified some errors and missing points in this article. First, in the “subgroup analysis by geographic location” on page 6; the association between beef consumption and colon cancer risk was mentioned as statistically significant in European studies although p value was 0.079, as seen in Table 1. This error should be corrected or clarified. Second, although there is a significant association between pork consumption and rectal cancer in European studies, as shown again in Table 1 (RR 5 1.08, p 5 0.007), this result was not mentioned neither in the article, nor in the abstract. Conversely, the abstract contains a lack of relationship between pork consumption and colorectal cancer (CRC). I think that the general statements may be overlooked important details. As the authors evaluated colon and rectal cancer separately beside CRC, new data support the existence of two categories of CRC based on site of origin.2 The aim of this meta-analysis is essentially to summarize and quantify the associations between meat subtypes and CRC.1 But, when we look at the Sato’s study, not only for meat subtypes but also there is not any significant association between total meat consumption and the risk of CRC.3 Because, the meat consumption is very low in the participants of this study; 70.4 g/day for highest quartile, which is the upper limit of recommended level (500 g/week) for healthy people according to guidelines.4 So, I think that it is questionable to take this type of completely negative study into specific meta-analyses. In addition, Figure 3 contains some minor different data than those of original publications such as upper limits of confidence intervals (CIs) in Norat’s and Sato’s articles, respectively; 1.47 for colorectal cancer and 2.63 (for colon), 1.41 (for rectal) should be 1.48 and 2.62, 1.42 according to the original data.3,5
C 2015 UICC Int. J. Cancer: 137, 1788 (2015) V
Finally, it seems that the relative risk (RR) for colorectal cancer in the Netherlands cohort study,6 RRs for colon and rectal cancer in Takachi’s article7 were calculated from pooled data mentioned in material and methods. But, RRs for colon and rectal cancer separately from Norat’s study which is the largest European cohort study (EPIC) were not included into Figure 2 and 3. In fact, the original article does not contain these data, but I am wondering if it was not possible to have and/or calculate them from EPIC Study Group in which they were two authors from Heidelberg, Germany. Yours sincerely, Nuri Faruk Aykan
References 1.
2. 3. 4.
5.
6.
7.
Carr PR, Walter V, Brenner H, et al. Meat subtypes and their association with colorectal cancer: systematic review and meta-analysis. Int J Cancer, in press. doi: 10.1002/ijc.29423. Iacopetta B. Are there two sides to colorectal cancer? Int J Cancer 2002;101: 403–8. Sato Y, Nakaya N, Kuriyama S, et al. Meat consumption and risk of colorectal cancer in Japan: the Miyagi cohort study. Eur J Cancer Prev 2006;15:211–8. 4. World Cancer Research Fund and American Institute for Cancer Research. Food, nutrition, physical activity and the prevention of cancer: a global perspective. Washington, DC: AICR, 2007. Norat T, Bingham S, Ferrari P, et al. Meat, fish, and colorectal cancer risk: the European prospective investigation into cancer and nutrition. J Natl Cancer Inst 2005;97:906–16. Brink M, Weijenberg MP, de Goeij AF, et al. Meat consumption and K-ras mutations in sporadic colon and rectal cancer in the Netherlands cohort study. Br J Cancer 2005;92:1310–20. Takachi R, Tsubono Y, Baba K, et al. Red meat intake may increase the risk of colon cancer in Japanese, a population with relatively low red meat consumption. Asia Pac J Clin Nutr 2011;20:603–12.
Author Disclosures: Author declares no conflicts of interest. DOI: 10.1002/ijc.29547 History: Received 21 Mar 2015; Accepted 1 Apr 2015; Online 4 Apr 2015 Correspondence to: Nuri Faruk Aykan, Department of Medical Oncology, Istanbul University, Institute of Oncology, Capa, Istanbul, Turkey, Tel.: +905332658907, E-mail: [email protected]
Red meat subtypes and colorectal cancer risk Nuri Faruk Aykan
Letter to the Editor
Department of Medical Oncology, Istanbul University, Institute of Oncology, Capa, Istanbul, Turkey
Dear Editor, I read with a great interest the manuscript of “Meat subtypes and their association with colorectal cancer: Systematic review and meta-analysis” reported by Prudence R. Carr and colleagues.1 I want to point out that I identified some errors and missing points in this article. First, in the “subgroup analysis by geographic location” on page 6; the association between beef consumption and colon cancer risk was mentioned as statistically significant in European studies although p value was 0.079, as seen in Table 1. This error should be corrected or clarified. Second, although there is a significant association between pork consumption and rectal cancer in European studies, as shown again in Table 1 (RR 5 1.08, p 5 0.007), this result was not mentioned neither in the article, nor in the abstract. Conversely, the abstract contains a lack of relationship between pork consumption and colorectal cancer (CRC). I think that the general statements may be overlooked important details. As the authors evaluated colon and rectal cancer separately beside CRC, new data support the existence of two categories of CRC based on site of origin.2 The aim of this meta-analysis is essentially to summarize and quantify the associations between meat subtypes and CRC.1 But, when we look at the Sato’s study, not only for meat subtypes but also there is not any significant association between total meat consumption and the risk of CRC.3 Because, the meat consumption is very low in the participants of this study; 70.4 g/day for highest quartile, which is the upper limit of recommended level (500 g/week) for healthy people according to guidelines.4 So, I think that it is questionable to take this type of completely negative study into specific meta-analyses. In addition, Figure 3 contains some minor different data than those of original publications such as upper limits of confidence intervals (CIs) in Norat’s and Sato’s articles, respectively; 1.47 for colorectal cancer and 2.63 (for colon), 1.41 (for rectal) should be 1.48 and 2.62, 1.42 according to the original data.3,5
C 2015 UICC Int. J. Cancer: 137, 1788 (2015) V
Finally, it seems that the relative risk (RR) for colorectal cancer in the Netherlands cohort study,6 RRs for colon and rectal cancer in Takachi’s article7 were calculated from pooled data mentioned in material and methods. But, RRs for colon and rectal cancer separately from Norat’s study which is the largest European cohort study (EPIC) were not included into Figure 2 and 3. In fact, the original article does not contain these data, but I am wondering if it was not possible to have and/or calculate them from EPIC Study Group in which they were two authors from Heidelberg, Germany. Yours sincerely, Nuri Faruk Aykan
References 1.
2. 3. 4.
5.
6.
7.
Carr PR, Walter V, Brenner H, et al. Meat subtypes and their association with colorectal cancer: systematic review and meta-analysis. Int J Cancer, in press. doi: 10.1002/ijc.29423. Iacopetta B. Are there two sides to colorectal cancer? Int J Cancer 2002;101: 403–8. Sato Y, Nakaya N, Kuriyama S, et al. Meat consumption and risk of colorectal cancer in Japan: the Miyagi cohort study. Eur J Cancer Prev 2006;15:211–8. 4. World Cancer Research Fund and American Institute for Cancer Research. Food, nutrition, physical activity and the prevention of cancer: a global perspective. Washington, DC: AICR, 2007. Norat T, Bingham S, Ferrari P, et al. Meat, fish, and colorectal cancer risk: the European prospective investigation into cancer and nutrition. J Natl Cancer Inst 2005;97:906–16. Brink M, Weijenberg MP, de Goeij AF, et al. Meat consumption and K-ras mutations in sporadic colon and rectal cancer in the Netherlands cohort study. Br J Cancer 2005;92:1310–20. Takachi R, Tsubono Y, Baba K, et al. Red meat intake may increase the risk of colon cancer in Japanese, a population with relatively low red meat consumption. Asia Pac J Clin Nutr 2011;20:603–12.
Author Disclosures: Author declares no conflicts of interest. DOI: 10.1002/ijc.29547 History: Received 21 Mar 2015; Accepted 1 Apr 2015; Online 4 Apr 2015 Correspondence to: Nuri Faruk Aykan, Department of Medical Oncology, Istanbul University, Institute of Oncology, Capa, Istanbul, Turkey, Tel.: +905332658907, E-mail: [email protected]
