The %subtype_trend macro tests whether the exposure-subtype association has a trend across the ordinal cancer subtypes. The user runs separate Cox (for cohort studies) or conditional logistic models (for nested case-control studies) for each subtype, and then tests the heterogeneity hypothesis using the outputs from the separate models, or the user takes the estimates (and standard errors) from the literature and test the heterogeneity hypothesis. In the subtype-specific analysis, the confounders-disease associations are allowed to be different among the subtypes.