It has been reported that anticancer treatment may cause cognitive impairment. Elderly patients in particular could be at increased risk for treatment-related cognitive deterioration. A consecutive series of cancer out-patients >or=65 years old were prospectively assessed by means of a neuropsychological test Cambridge Cognitive Examination (CAMCOG) test at baseline, and after 3 and 6 months from study entry. Patients were categorized in three groups (group 1, no anticancer treatment; group 2, receiving chemotherapy; group 3, receiving endocrine therapy). Comprehensive geriatric assessment was performed at the three time points evaluation. Sixty-one patients were enrolled (32, 16 and 13, in groups 1, 2, and 3, respectively). At baseline, cognitive function was directly correlated to Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL) scores and was associated with higher educational level and absence of depression. Overall, cognitive function did not worsen across time in each group. However, more patients in the CT group showed worsening in memory skills, and more patients in the ET and CT group experienced reduction in the attention score.