MUC5AC and adenocarcinoma in situ: These subgroups comprise the following: AIS (adenocarcinoma in situ), minimally invasive adenocarcinoma (3-cm lepidic predominant tumour with an invasion of ≤5 mm), lepidic predominant, acinar predominant, papillary predominant, micropapillary predominant, solid predominant with mucin production and invasive adenocarcinoma variants.