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By Cristina Curcelli
August 13, 2015
COGNITIVE EFFECTS OF HORMONAL THERAPY
IN BREAST CANCER PATIENTS
Background: Hormonal therapy Common uses Types:
SERM v. AI
Study designs Tamoxifen Tamoxifen vs. Aromatose Inhibitors Anastrozole
Limits to Research
Conclusions
OUTLINE
What is hormonal therapy?BACKGROUND INFO
Approx. 2/3 of breast cancers are hormone-receptor positive
Most commonly used as adjuvant therapy
Despite prevalence, relatively little research has looked at possible cognitive effects.
HORMONAL THERAPY: COMMON USES
Selective Estrogen Receptor Modulator (SERM): Selectively act as estrogen agonists or antagonists Action varies based on tissue type Ex: Tamoxifen
THERAPY TYPE: SERM
Aromatose Inhibitor (AI): Aromatose: enzyme that synthesizes estrogen AIs block all production of estrogen
Generally used on postmenopausal women only Have been shown to be more effective than tamoxifen in
preventing recurrence
Types: exemestane, anastrozole, letrozole
THERAPY TYPE: AI
Exemestane: irreversible, steroidal aromatose inactivator Acts by way of “suicide inhibition”
Anastrozole: non-steroidal aromatose inhibiting drug Binds reversibly to enzyme by competitive inhibition
Letrozole: non-steroidal aromatose inhibiting drug Competitive, reversible binding
AROMATOSE INHIBITOR TYPES, CONT.
Inclusion criteriaSTUDY DESIGNS
WHY STUDY HORMONAL THERAPY?
Many Breast Cancer patients complained of cognitive problems
There is growing evidence that estrogen affects cognitive function Estrogen-receptors (ERs) are present in the hippocampus and
frontal lobe, areas important for cognitive function
Studies included here: Post-menopausal women Breast cancer (early - mid stage) Cross sectional and longitudinal designs Controlled for type of hormone (tamoxifen v. exemestame v.
anastrozole)
APPROACH TO RESEARCH
Studies examining effects of Tamoxifen against controls
STUDIES: TAMOXIFEN
Castellon et al, 2004: Cross sectional design Tamoxifen/chemo group, chemo only group, healthy controls
Tamoxifen/chemo group showed greatest cognitive function compromise
Domains most severely affected: Visual memory Visuospatial function Verbal learning
STUDIES: EFFECTS OF TAMOXIFEN
Boele et al, 2014: long-term tamoxifen therapy Cross sectional design Tamoxifen + surgery/radiation group, surgery/radiation only
group, healthy controls
Tamoxifen group performed significantly worse on measures of verbal memory.
EFFECTS OF TAMOXIFEN, CONT.
SERMs vs. AIs
STUDIES: COMPARISONS
Because of differing mechanisms, AI therapies – specific anastrozole -- are thought to affect cognitive function MORE than tamoxifen (SERM).
Exemstane: Schilder et al’s prospective study Tamoxifen group, exemestane group, healthy
controls Tamoxifen users shown to have statistically lower
verbal memory and executive function at 1 year mark
Exemestane users showed no difference.
SERM VS. AI THERAPY
Anastrozole:
Bender’s 2007 cross-sectional study Tamoxifen group, anastrozole group, healthy controls Anastrozole group showed poorer verbal and visual
learning and memory than tamoxifen group.
Collins et al: 2008 prospective study Tamoxifen group, anastrozole group, healthy controls Reliable cognitive decline in both cancer groups Anastrozole, at 5-6 months after initial timepoint, showed more
significantly increased risk of decline compared to tamoxifen group
SERM VS. AI THERAPY, CONT.
Prospective study examining effects of Anastrazole
STUDY: ANASTRAZOLE
Bender et al 2015 Prospective study: 4 timepoints 3 groups: anastrozole only, chemo + anastrozole, healthy controls Cancer groups showed poorer executive function at nearly all
timepoints
Patterns of deterioration in cancer groups between 0 – 6 months Afffected domains:
Working memory ConcentrationDeterioration patters continued in anastrozole only group from 12-18 months
Deterioration patters continued in anastrozole only group from 12-18 months
EFFECTS OF ANASTROZOLE
Limits
Conclusions
Future Direction
CONCLUSIONS
Cross sectional studies
Small sample sizes
Comparison between AIs and SERMs
Difficulty in consistent exclusion/inclusion criteria
LIMITS TO CURRENT FINDINGS
Commonly affected domains: Verbal memory + learning Executive function
Relation to ER structural location
Consistencies across studies Tamoxifen shown to affect executive function and verbal
memory Both cross-sectional and prospective results
Anastrozole shown to affect congitive function in comparison to Tamoxifen, effects have generally been more severe
CONCLUSIONS
Further focus on prospective studies
Understaning mechanisms of Tamoxifen Antagonist/agonist behavior
Isolating type of Aromatose Inhibitor Exemestame Anastrozole Letrozole
DIRECTION OF FUTURE RESEARCH
Agrawa l K , Onami S , Mor t imer JE , Pa l SK . Cogn i t i ve changes assoc ia ted w i th endoc r ine the rapy fo r b reas t cancer. Matu r i t as . 2010 ;67 .
Bender CM , e t a l . Memory impa i rmen t s w i th ad juvan t anast ro zo le versus tamox fen i n women w i th ea r ly - s tage b reas t cancer. Menopause . 2007 ; 14 (6 ) : 995-998 .
Bender CM , e t a l . Pa t te rns o f Change i n Cogn i t i ve Func t ion w i th Anas t rozo le T herapy. Cancer. 2015 Aug 1 ;121 (15 ) :2627 -36 .
Boe le FW, Sch i l de r CMT , de Roode ML , De i jen JB , Schagen SB . Cogn i t i ve func t i on ing du r ing long -te rm tamox i fen t rea tment in pos temenopausa l women w i th b reas t cancer. Menopause . 2014;22 :1 .
Caste l lon , S A , e t a l . Neu rocogn i t i ve Per fo rmance i n Breas t Cancer Su rv i vo rs Exposed to Ad juvant Chemotherapy and Tamox i fen . J ou rna l o f C l i n i c a l and Expe r imen ta l Neu ropsycho logy. 2004;26 :7 .
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Eber l ing JL , Wu C , Tong -Tu rnbeaugh R , J agus t , WJ . Es t rogen- and t amox i fen -assoc ia ted effec ts on b ra in s t ruc tu re and func t ion . Neuro Image . 2004 ; 21 : 364 -371 .
Sc h i lder CM , e t a l . Effec ts o f Tamox i fen and Exemestane on Cogn i t i ve Func t i on ing o f Pos tmenopausa l Pa t i en ts w i th Breas t Cance r. J ou rna l o f C l in i c a l Onco logy. 2010;28 :8
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