Cognitive function before and after whole brain radiotherapy: in regard to Welzel et al. (Int J Radiat Oncol Biol Phys 2008;72:1311-1318).

摘要

I read with interest the article by Welzel and colleagues (1), which demonstrated that whole-brain radiotherapy (WBRT) caused cognitive dysfunction immediately after the beginning of radiotherapy in patients with brain metas-tases only. At 6 to 8 weeks after the end of WBRT, cognitive dysfunction was seen in patients with and without brain metastases. The methods and interpretation of the results, however, raise several concerns. At the introduction of the study, the authors evaluated three groups of patients: the prophylactic cranial irradiation (PCI) group, consisting of 11 patients with small-cell lung cancer (SCLC); the therapeutic cranial irradiation (TCI) group (n - 16), consisting of 11 patients with non-small-cell lung cancer (NSCLC); and a control group, consisting of 15 patients with breast cancer. Unfortunately, the candidates were not appropriate for the study, and the conclusion was misleading for the following reasons. First, there are data suggesting that even before treatment, cognitive dysfunction is prevalent among patients with several types of malignancy, including those with SCLC and breast cancer, which may favor the contribution of subclinical paraneoplastic syndromes or other tumor-associated factors (2, 3). In contrast, little is known about cognitive dysfunction before treatment among patients with NSCLC. Therefore, perhaps the presence of different kinds of neoplasms in different groups could have skewed the effect of PCI and TCI on memory function.