Association between adjuvant regional radiotherapy and cognitive function in breast cancer patients treated with conservation therapy.
Although protracted cognitive impairment has been reported to occur after radiotherapy even when such therapy is not directed to brain areas, the mechanism remains unclear. This study investigated whether breast cancer patients exposed to local radiotherapy showed lower cognitive function mediated by higher plasma interleukin (IL)-6 levels than those unexposed. We performed the Wechsler Memory Scale-Revised (WMS-R) and measured plasma IL-6 levels for 105 breast cancer surgical patients within 1 year after the initial therapy. The group differences in each of the indices of WMS-R were investigated between cancer patients exposed to adjuvant regional radiotherapy (n = 51) and those unexposed (n = 54) using analysis of covariance. We further investigated a mediation effect by plasma IL-6 levels on the relationship between radiotherapy and the indices of WMS-R using the bootstrapping method. The radiotherapy group showed significantly lower Immediate Verbal Memory Index and Delayed Recall Index (P = 0.001, P = 0.008, respectively). Radiotherapy exerted an indirect effect on the lower Delayed Recall Index of WMS-R through elevation of plasma IL-6 levels (bootstrap 95% confidence interval = -2.6626 to -0.0402). This study showed that breast cancer patients exposed to adjuvant regional radiotherapy in conservation therapy might have cognitive impairment even several months after their treatment. The relationship between the therapy and the cognitive impairment could be partially mediated by elevation of plasma IL-6 levels.
Department of Stress Sciences and Psychosomatic Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Osamu
O
Shibayama
Kazuhiro
K
Yoshiuchi
Masatoshi
M
Inagaki
Yutaka
Y
Matsuoka
Eisho
E
Yoshikawa
Yuriko
Y
Sugawara
Tatsuo
T
Akechi
Noriaki
N
Wada
Shigeru
S
Imoto
Koji
K
Murakami
Asao
A
Ogawa
Akira
A
Akabayashi
Yosuke
Y
Uchitomi
D001921:Brain / Q000528:radiation effects*; D001943:Breast Neoplasms / Q000097:blood / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D003071:Cognition / Q000528:radiation effects*; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008279:Magnetic Resonance Imaging; D008568:Memory / Q000528:radiation effects; D008875:Middle Aged; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects*
D015850:Interleukin-6
Breast cancer; Wechsler Memory Scale-Revised; cognitive impairment; interleukin-6; radiotherapy