Vitamin D and Cancer Incidence−−Response to Grant Tea Skaaby, Lise Lotte Nystrup Husemoen and Allan Linneberg Cancer Epidemiol Biomarkers Prev 2014;23:1951.
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Cancer Epidemiology, Biomarkers & Prevention
Letter to the Editor
Vitamin D and Cancer Incidence—Response to Grant Tea Skaaby1, Lise Lotte Nystrup Husemoen1, and Allan Linneberg1,2,3
We thank Grant (1) for his thoughtful reading and commenting of our article (2). First, Grant mentions that the long follow-up time in the study may be the reason for not finding statistically significant associations between vitamin D and cancer risk. In additional analyses not included in our article, we therefore included a maximum of 5 years of follow-up only (5.0 year median follow-up time). Hazard ratios [HR; number of events (n)/total number (N); 95% confidence intervals (CI)] per 10 nmol/L higher baseline vitamin D level were now (only categories with >20 events are shown): for all cancers (n ¼ 371/N ¼ 10,709; HR, 1.03; 95% CI, 0.98–1.07), all cancers excluding non-melanoma skin cancer (NMSC; n ¼ 297/ N ¼ 10,866; HR, 1.01; 95% CI, 0.96–1.06), colorectal cancer (n ¼ 43/N ¼ 11,119; HR, 0.94; 95% CI, 0.82–1.08), cancer of
1 Research Centre for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark. 2Department of Clinical Experimental Research, Glostrup University Hospital, Glostrup, Denmark. 3Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Corresponding Author: Tea Skaaby, Research Centre for Prevention and Health, Glostrup Hospital, Nordre Ringvej 57, DK-2600 Glostrup, Denmark. Phone: 45-38634383; Fax: 45-38633977; E-mail: [email protected] doi: 10.1158/1055-9965.EPI-14-0670 2014 American Association for Cancer Research.
bronchus and lung (n ¼ 32/N ¼ 11,133; HR, 1.04; 95% CI, 0.91–1.19), breast cancer (n ¼ 72/N ¼ 5,606; HR, 1.02; 95% CI, 0.93–1.12), prostate cancer (n ¼ 29/N ¼ 5,451; HR, 1.03; 95% CI, 0.88–1.21), NMSC (n ¼ 98/N ¼ 10,972; HR, 1.09; 95% CI, 1.01–1.18), and malignant melanoma (n ¼ 22/N ¼ 11,100; HR, 1.00; 95% CI, 0.84–1.19). Thus, consistent with our published results, our data do not support the hypothesis that there is a beneficial effect of a higher vitamin D status on cancer risk when using shorter follow-up time. Another concern raised is the different levels of vitamin D in the three studies. To take this into account, we performed meta-analyses of the study-specific estimates (2, 3). Despite signs of heterogeneity across the cohorts, the estimates were quite similar to the results from the pooled data analyses. In addition, the limitation of the assumption of a linear association between vitamin D and risk of cancer is mentioned. In fact, we analyzed the data both with vitamin D status in season-specific quartiles and as a continuous variable where we found the quadratic term of vitamin D status nonsignificant in all models (2). In this way, there were no signs of nonlinear relationships between vitamin D status and cancer risk. Disclosure of Potential Conflicts of Interest No potential conflicts of interest were disclosed. Received June 11, 2014; accepted June 11, 2014; published online September 2, 2014.
References 1. Grant WB. Vitamin D and cancer incidence—letter from Grant. Cancer Epidemiol Biomarkers Prev 2014;23:1950. 2. Skaaby T, Husemoen LL, Thuesen BH, Pisinger C, Jorgensen T, Roswall N, et al. Prospective population-based study of the association between serum 25-hydroxyvitamin-D levels and the incidence
of specific types of cancer. Cancer Epidemiol Biomarkers Prev 2014; 23:1220–9. 3. Riley RD, Lambert PC, Abo-Zaid G. Meta-analysis of individual participant data: rationale, conduct, and reporting. BMJ 2010; 340:c221.
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Downloaded from cebp.aacrjournals.org on September 12, 2014. © 2014 American Association for Cancer Research.
1951
Updated version
Access the most recent version of this article at: http://cebp.aacrjournals.org/content/23/9/1951
Cited Articles
This article cites by 3 articles, 3 of which you can access for free at: http://cebp.aacrjournals.org/content/23/9/1951.full.html#ref-list-1
Citing articles
This article has been cited by 1 HighWire-hosted articles. Access the articles at: http://cebp.aacrjournals.org/content/23/9/1951.full.html#related-urls
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Sign up to receive free email-alerts related to this article or journal. To order reprints of this article or to subscribe to the journal, contact the AACR Publications Department at [email protected]. To request permission to re-use all or part of this article, contact the AACR Publications Department at [email protected].
Downloaded from cebp.aacrjournals.org on September 12, 2014. © 2014 American Association for Cancer Research.
Cancer Epidemiology, Biomarkers & Prevention
Letter to the Editor
Vitamin D and Cancer Incidence—Response to Grant Tea Skaaby1, Lise Lotte Nystrup Husemoen1, and Allan Linneberg1,2,3
We thank Grant (1) for his thoughtful reading and commenting of our article (2). First, Grant mentions that the long follow-up time in the study may be the reason for not finding statistically significant associations between vitamin D and cancer risk. In additional analyses not included in our article, we therefore included a maximum of 5 years of follow-up only (5.0 year median follow-up time). Hazard ratios [HR; number of events (n)/total number (N); 95% confidence intervals (CI)] per 10 nmol/L higher baseline vitamin D level were now (only categories with >20 events are shown): for all cancers (n ¼ 371/N ¼ 10,709; HR, 1.03; 95% CI, 0.98–1.07), all cancers excluding non-melanoma skin cancer (NMSC; n ¼ 297/ N ¼ 10,866; HR, 1.01; 95% CI, 0.96–1.06), colorectal cancer (n ¼ 43/N ¼ 11,119; HR, 0.94; 95% CI, 0.82–1.08), cancer of
1 Research Centre for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark. 2Department of Clinical Experimental Research, Glostrup University Hospital, Glostrup, Denmark. 3Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Corresponding Author: Tea Skaaby, Research Centre for Prevention and Health, Glostrup Hospital, Nordre Ringvej 57, DK-2600 Glostrup, Denmark. Phone: 45-38634383; Fax: 45-38633977; E-mail: [email protected] doi: 10.1158/1055-9965.EPI-14-0670 2014 American Association for Cancer Research.
bronchus and lung (n ¼ 32/N ¼ 11,133; HR, 1.04; 95% CI, 0.91–1.19), breast cancer (n ¼ 72/N ¼ 5,606; HR, 1.02; 95% CI, 0.93–1.12), prostate cancer (n ¼ 29/N ¼ 5,451; HR, 1.03; 95% CI, 0.88–1.21), NMSC (n ¼ 98/N ¼ 10,972; HR, 1.09; 95% CI, 1.01–1.18), and malignant melanoma (n ¼ 22/N ¼ 11,100; HR, 1.00; 95% CI, 0.84–1.19). Thus, consistent with our published results, our data do not support the hypothesis that there is a beneficial effect of a higher vitamin D status on cancer risk when using shorter follow-up time. Another concern raised is the different levels of vitamin D in the three studies. To take this into account, we performed meta-analyses of the study-specific estimates (2, 3). Despite signs of heterogeneity across the cohorts, the estimates were quite similar to the results from the pooled data analyses. In addition, the limitation of the assumption of a linear association between vitamin D and risk of cancer is mentioned. In fact, we analyzed the data both with vitamin D status in season-specific quartiles and as a continuous variable where we found the quadratic term of vitamin D status nonsignificant in all models (2). In this way, there were no signs of nonlinear relationships between vitamin D status and cancer risk. Disclosure of Potential Conflicts of Interest No potential conflicts of interest were disclosed. Received June 11, 2014; accepted June 11, 2014; published online September 2, 2014.
References 1. Grant WB. Vitamin D and cancer incidence—letter from Grant. Cancer Epidemiol Biomarkers Prev 2014;23:1950. 2. Skaaby T, Husemoen LL, Thuesen BH, Pisinger C, Jorgensen T, Roswall N, et al. Prospective population-based study of the association between serum 25-hydroxyvitamin-D levels and the incidence
of specific types of cancer. Cancer Epidemiol Biomarkers Prev 2014; 23:1220–9. 3. Riley RD, Lambert PC, Abo-Zaid G. Meta-analysis of individual participant data: rationale, conduct, and reporting. BMJ 2010; 340:c221.
www.aacrjournals.org
Downloaded from cebp.aacrjournals.org on September 12, 2014. © 2014 American Association for Cancer Research.
1951
