10.1111/(ISSN)1398-9995 ALL Allergy Allergy 0105-4538 1398-9995 10.1111/all.14616 ALL14616 LETTER TO THE EDITOR LETTERS TO THE EDITOR Assessing the protective role of allergic disease in gastrointestinal tract cancers using Mendelian randomization analysis Yuan Shuai https://orcid.org/0000-0001-5055-5627 ¹ Vithayathil Mathew ² Kar Siddhartha ³ Carter Paul ⁴ Mason Amy M. ^{5 6} Xie Shao‐Hua ⁷ Burgess Stephen ^{4 8} Larsson Susanna C. https://orcid.org/0000-0003-0118-0341 susanna.larsson@ki.se * ^{1 9 1} Unit of Cardiovascular and Nutritional Epidemiology Institute of Environmental Medicine Karolinska Institutet Stockholm Sweden ² MRC Cancer Unit University of Cambridge Cambridge UK ³ MRC Integrative Epidemiology Unit Bristol Medical School University of Bristol Bristol UK ⁴ Department of Public Health and Primary Care University of Cambridge Cambridge UK ⁵ British Heart Foundation Cardiovascular Epidemiology Unit Department of Public Health and Primary Care University of Cambridge Cambridge UK ⁶ National Institute for Health Research Cambridge Biomedical Research Centre University of Cambridge and Cambridge University Hospitals Cambridge UK ⁷ Upper Gastrointestinal Surgery Department of Molecular Medicine and Surgery Karolinska Institutet Karolinska University Hospital Stockholm Sweden ⁸ MRC Biostatistics Unit University of Cambridge Cambridge UK ⁹ Department of Surgical Sciences Uppsala University Uppsala Sweden * Correspondence Susanna C. Larsson, Institute of Environmental Medicine, Karolinska Institutet, Nobelsväg 13, Stockholm, 17177, Sweden; Department of Surgical Sciences, Uppsala University, Dag Hammarskjölds Väg 14B, Uppsala, 75185, Sweden. Email: susanna.larsson@ki.se 21 10 2020 05 2021 76 5 10.1111/all.v76.5 1559 1562 11 09 2020 10 08 2020 30 09 2020 © 2021 EAACI and John Wiley and Sons A/S © 2020 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd 2020 © 2020 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd http://creativecommons.org/licenses/by-nc/4.0/ This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society 204623/Z/16/Z EC‐Innovative Medicines Initiative Cancer Research UK programme grant C18281/A19169 Hjärt‐Lungfonden http://dx.doi.org/10.13039/501100003793 20190247 Vetenskapsrådet http://dx.doi.org/10.13039/501100004359 2019‐00977 Forskningsrådet om Hälsa, Arbetsliv och Välfärd http://dx.doi.org/10.13039/501100006636 2018‐00123