Metabolic activity in the insular cortex and hypothalamus predicts hot flashes: an FDG-PET study.
BACKGROUND
Hot flashes are a common side effect of adjuvant endocrine therapies (AET; leuprolide, tamoxifen, aromatase inhibitors) that reduce quality of life and treatment adherence in breast cancer patients. Because hot flashes affect only some women, preexisting neurobiological traits might predispose to their development. Previous studies have implicated the insula during the perception of hot flashes and the hypothalamus in thermoregulatory dysfunction.


OBJECTIVE
The aim of the study was to understand whether neurobiological factors predict hot flashes.


METHODS
[18F]-Fluorodeoxyglucose (FDG) positron emission tomography (PET) brain scans coregistered with structural magnetic resonance imaging were used to determine whether metabolic activity in the insula and hypothalamic thermoregulatory and estrogen-feedback regions measured before and in response to AET predict hot flashes. Findings were correlated with CYP2D6 genotype because of CYP2D6 polymorphism associations with tamoxifen-induced hot flashes.


METHODS
We measured regional cerebral metabolic rate of glucose uptake (rCMRglu) in the insula and hypothalamus on FDG-PET.


RESULTS
Of 18 women without hot flashes who began AET, new-onset hot flashes were reported by 10 (55.6%) and were detected objectively in nine (50%) participants. Prior to the use of all AET, rCMRglu in the insula (P ≤ 0.01) and hypothalamic thermoregulatory (P = 0.045) and estrogen-feedback (P = 0.007) regions was lower in women who reported developing hot flashes. In response to AET, rCMRglu was further reduced in the insula in women developing hot flashes (P ≤ 0.02). Insular and hypothalamic rCMRglu levels were lower in intermediate than extensive CYP2D6 metabolizers.


CONCLUSIONS
Trait neurobiological characteristics predict hot flashes. Genetic variability in CYP2D6 may underlie the neurobiological predisposition to hot flashes induced by AET.
Center for Women's Mental Health, Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston Massachusetts 02114, USA. hjoffe@partners.org
Hadine
H
Joffe
Thilo
T
Deckersbach
Nancy U
NU
Lin
Nikos
N
Makris
Todd C
TC
Skaar
Scott L
SL
Rauch
Darin D
DD
Dougherty
Janet E
JE
Hall
D000328:Adult; D015415:Biomarkers; D001833:Body Temperature Regulation / Q000187:drug effects / Q000502:physiology; D002540:Cerebral Cortex / Q000000981:diagnostic imaging* / Q000378:metabolism*; D019389:Cytochrome P-450 CYP2D6 / Q000097:blood / Q000235:genetics; D005260:Female; D019788:Fluorodeoxyglucose F18; D005838:Genotype; D005947:Glucose / Q000493:pharmacokinetics; D006728:Hormones / Q000009:adverse effects / Q000627:therapeutic use; D019584:Hot Flashes / Q000000981:diagnostic imaging* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007031:Hypothalamus / Q000000981:diagnostic imaging* / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008593:Menopause / Q000502:physiology; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals
D015415:Biomarkers; D006728:Hormones; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D019389:Cytochrome P-450 CYP2D6; D005947:Glucose