Cognitive functioning in thyroid cancer survivors: a systematic review and meta-analysis

Background Some thyroid cancer (TC) survivors experience cognitive symptoms. Purpose The purpose of this study is to perform a systematic literature review and meta-analysis comparing cognitive performance in TC survivors to controls. Methods We performed a seven-database electronic search and hand-search. We performed duplicate independent reviews and data abstraction. Random effects meta-analyses reported standardized mean differences (SMDs) with 95% confidence intervals (CIs), where a negative value implies worse performance in the TC group. Results We reviewed 1174 unique citations and 10 full-text papers. We included seven studies of 241 treated TC survivors and 273 controls. Cognitive function was statistically significantly worse in TC survivors in the following domains: Attention and Concentration (Digit Span Forwards) SMD − 0.37 (95% CI − 0.62, − 0.13, p = 0.003, four studies), Speed of Processing (Trail Making A) SMD − 0.36 (95% CI − 0.66, − 0.05, p = 0.022, four studies), and Language (Controlled Oral Word Association [COWAT]-Categories) SMD − 0.97 (95% − 1.31, − 0.64, p < 0.001, two studies). Executive Function results varied: COWAT-Letters SMD − 0.60 (95% CI − 0.94, − 0.27, p < 0.001, two studies), Digit Span Backwards SMD − 0.40 (95% CI − 0.64, − 0.15, p = 0.002, four studies), and Trail Making B test SMD − 0.20 (95% CI − 0.51, 0.10, p = 0.191, four studies). Statistical heterogeneity limited the COWAT-Categories and Digit Span Backwards meta-analyses. Conclusions Cognitive function was worse in TC survivors in multiple domains. Limitations included few studies, potential confounding, and lack of prospective data. Implications for Cancer Survivors TC survivors may experience impairments in cognitive function and should report cognitive concerns to healthcare practitioners.