a, b Flowchart of participants in samples 1 and 2. The association between incident dementia and cancer was studied in sample 1. For sample 1, all participants of the Rotterdam Study were included at study entry, that is, the first rounds of the first (RS-I), second (RS-II), and third cohort (RS-III). In total, sample 1 consisted of 13,207 participants. Sample 2 originated from the fourth follow-up round of RS-I, the second round of RS-II, and the first round of RS-III. In this sample, the association between MCI and cancer was investigated after excluding participants with prevalent dementia, since the absence of dementia is part of the definition of MCI. In addition, a comparative analysis was performed in sample 2 investigating the risk of cancer in patients with prevalent dementia. For this comparative analysis, persons with MCI were excluded. MCI, mild cognitive impairment.