“…Comparing our findings with others is complicated by methodological differences. Others have limited their cohorts to those surviving from 6 months to 5 years after their initial cancer diagnosis [5,6,[29], [30], [31], [32], [33], [34]]; required cohort consent [5]; used more dated cohorts diagnosed prior to 2000 [5,6,32]; included all subsequent cancers [3,5,17,34,35]; included in situ tumours and/or non-melanoma skin cancers and/or all tumours arising in the brain and central nervous system [29,31,33]; relied on self-report to ascertain subsequent cancers [5,33]; and, have rarely acknowledged or discussed the impact of multiple primary reporting rules [6,17,19,35].…”