Cognitive Complaints After Breast Cancer Treatments: Patient Report and Objective Evidence

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The report by Ganz et al. in this issue of the Journal is an ambitious study that adds to the body of work assessing the neurocognitive effects of cancer and cancer treatment ( 1 ). Cognitive dysfunction, although frequently subtle, occurs in many cancer patients before, during, and long after diagnosis and treatment. There are now more than 12 million cancer survivors in the United States. One out of six people aged 65 years or older is a cancer survivor; 1.4 million of these survivors were diagnosed more than 20 years ago. With advances in early detection and treatment, cancer is becoming a chronic illness. However, cancer patients experience a number of adverse symptoms, including cognitive impairment, fatigue, pain, and sleep disturbance, most frequently in combination. This has been documented in a number of clinical human studies and animal models and has been investigated long enough to generate a number of meta-analyses and review articles ( 2–6 ). There are two issues to keep in mind regarding cognitive symptoms related to cancer treatment, which at first may seem contradictory. First, it is likely that scientific studies of this syndrome underestimate the true incidence in the overall cancer population. Second, applying these research data to individuals in the clinic with cognitive complaints is complex and requires a differential diagnosis.