<p>Abbreviations: ICD-O-3, International Classification of Diseases for Oncology, 3<sup>rd</sup> edition; MALT, mucosa-associated lymphoid tissue; NOS, not otherwise specified.</p>1<p>N after exclusion of prevalent cases at baseline.</p>2<p>N cases available for analyses, after exclusion of missing and inconsistent data. Only case numbers for subtypes with sufficient number of cases are given (so subgroups do not add up to 1,233).</p