Clinical Trial Details
— Status: Active, not recruiting
Administrative data
| NCT number |
NCT02078531 |
| Other study ID # |
2013/01005 |
| Secondary ID |
|
| Status |
Active, not recruiting |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
October 29, 2014 |
| Est. completion date |
October 2020 |
Study information
| Verified date |
September 2020 |
| Source |
National University Hospital, Singapore |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
The purpose of the study is to examine cognitive and brain function in stage I-III breast
cancer patients who have undergone adjuvant systemic therapy (chemotherapy or chemotherapy
plus anti-hormonal therapy) in comparison to a group of healthy controls.
Our hypothesis is that systemic adjuvant therapy in the form of chemotherapy or chemotherapy
and anti-hormonal therapy given to primary breast cancer patients can cause cognitive
impairment. We hypothesize that the use of simultaneous PET/MRI will allow us to determine
key regions in the brain that show metabolic, structural, and functional deficits in a
semi-quantitative manner and reveal subtle changes that are often missed during
neuropsychological tests due to the low sensitivity of neuropsychological batteries.
Description:
Breast cancer is the most common cancer amongst women worldwide, with a lifetime risk of 7-8%
in women and incidence rates ranging from 19.3-89.7 per 100,000 women in developing and
developed countries. More than 1,383,500 cases of invasive breast cancer are estimated to be
diagnosed worldwide,and approximately 1490 women were diagnosed to have breast cancer in
Singapore every year. However, the mortality rates are lesser at 6-19 per 100,000 women
because of the more favourable survival of breast cancer in high-incidence developed regions.
In Southeast Asian Chinese 5-year overall survival is about 75.8%, although lower for Indians
and Malays at 68% and 58.5% respectively. These improving outcomes are largely due to earlier
detection and the availability of more successful treatment options. With rising prevalence
of this disease and improving survivorship, the long term effects of current treatment
options are becoming increasingly survivorship issues.An early Early Breast Trialists'
Collaborative Group (EBCTCG) meta-analyses, reported that adjuvant chemotherapy produces an
absolute 10-year survival improvement of 7-11% for those < 50 years of age, and 2- 3% for
those aged 50 -69 years. This benefit was most recently confirmed by an update which reported
that adjuvant chemotherapy trials demonstrated recurrence and mortality reductions compared
to no-chemotherapy trials.Hence, chemotherapy remains an important strategy in the adjuvant
setting. However, several studies have reported reduced cognitive function in a proportion of
breast cancer patients receiving chemotherapy, also known as the "chemobrain" effect. In
these patients, cognitive impairments ranging from deficits in memory, attention,
concentration, executive and psychomotor functioning to deficits in nearly all cognitive
domains have been reported. Other studies however have disputed this association, and it thus
remains unclear if cognitive impairment is indeed a potential risk of systemic treatment.
There are a number of difference adjuvant chemotherapy regimens which comprise anthracyclines
and/or taxanes in various regimens. An adjuvant regimen utilising weekly paclitaxel after
standard doxorubicin/cyclophosphamide has been shown to improve disease-free and overall
survival over 3-weekly taxanes given after the same standard anthracycline-based regimen In
order to minimise heterogeneity, this study will only recruit patients utilising this
adjuvant chemotherapy regimen.Anti-hormonal therapy has become a mainstay in the adjuvant
treatment of hormone receptor-positive patients. Tamoxifen for 5 years reduces recurrence
rates throughout the first 10 years (RR 0·53 during years 0-4 and RR 0·68 [0·06] during years
5-9 [both 2p<0·00001]; and breast cancer mortality by about a third throughout the first 15
years. In addition, the use of aromatase inhibitors (AIs) in post-menopausal breast cancers
has been reported to confer a significant 2.9% decrease in recurrence compared with tamoxifen
(9.6% for AI v 12.6% for tamoxifen; 2P < .00001) and a non-significant absolute 1.1% decrease
in breast cancer mortality (4.8% for AI v 5.9% for tamoxifen; 2P = .1) in a recent
meta-analyses by Dowsett et al.Compared to chemotherapy, there is a relative paucity of data
pertaining to endocrine therapy-induced cognitive changes. Nonetheless, there have been
several pertinent studies examining datasets within the larger context of pre-existing large
multicenter adjuvant hormonal therapy trials which are outlined below.A growing body of
literature suggests that adjuvant systemic therapy for breast cancer may be associated with
cognitive impairment, which may persist for years and can impair decision-making abilities
and disrupt the ability of women to fulfill family, career, and community
responsibilities.The magnitude of these deficits may be moderated by depression, anxiety,
fatigue, concomitant medications, genetics, education, intelligence, and menopause.Studies
associating cognitive changes with chemotherapy had been reported since the mid 1970s;but
systematic research did not come about until the mid 1990's to early 2000's.However, early
studies were limited by lack of a pre-treatment assessment, the importance of which is
illustrated by a study by Wefel et al.This was one of the first prospective longitudinal
studies comparing pre- and post-treatment cognitive measures. Although there were no mean
differences between patients who received 5- fluorouracil/doxorubicin/ cyclophosphamide (FAC)
chemotherapy and normal controls, intra-individual analyses in patients demonstrated a 61%
cognitive decline for learning, attention and processing speed. Without a baseline
assessment, 46% of patients who had normal post-treatment scores would have their cognitive
impairments missed, highlighting that cognitive dysfunctions can be subtle and small
differences may be clinically significant. Furthermore, although acute cognitive changes
during chemotherapy are common,long-term post-treatment cognitive changes seem to persist in
only 17-34% of cancer survivors.Several additional longitudinal studies since then have
assessed cancer or treatment-related cognitive difficulties using standard neuropsychological
assessments.About 12-82% of patients had detected cognitive impairments in the domains of
executive function, memory, psychomotor speed and attention, these being the most frequent
measures affected. These studies used a variety of cognitive assessment tools and control
groups, different treatment regimens and varying testing timepoints. A study comparing breast
cancer patients, majority of which were exposed to adjuvant anthracycline and/or taxane-based
chemotherapy, to those breast cancer patients who were chemonaive or healthy controls,
reported the greatest deficits in processing speed and verbal ability domains for the
chemotherapy-exposed group. Therefore, research is needed needed to look at the factors
contributing to a decline and thereafter, a long-lasting impairment.Of interest, cognitive
deficits have been detected in cancer patients pre-chemotherapy in several studies. For
instance, Wefel et al described 33% of women in the current cohort exhibiting cognitive
impairment even before systemic therapy.Another study reported a 23% impairment in cognition
prior to adjuvant breast cancer chemotherapy.These could be related to psychological
variables such as stress, anxiety or depression, or to other factors such as differing
socioeconomic, educational or intrinsic cognitive levels. Research is needed to look at the
factors contributing to a decline and thereafter, a long-lasting impairment. These data also
suggest that systemic therapy-associated cognitive changes need to be examined within the
broader context of risk factors and biological processes associated with cancer
development.Inclusion of assessments of confounding factors which could play a role in
influencing cognitive function is vital. Fan et al in their study reported that fatigue,
menopausal symptoms and cognitive were important adverse effects of chemotherapy that
improved in most patient over a period of 1-2 years.In comparison, hormonal therapy had
minimal impact on them. Self-perceived cognitive deficits may not be reflective of objective
test scores and hence is interesting to evaluate. In a population-based study in Denmark
consisting of women <60 years old who received adjuvant anthracycline-based chemotherapy or
tamoxifen compared with healthy controls, it was shown that the patients were up to 3 times
more likely than healthy controls to rate themselves cognitively impaired at 6 months,
although neuropsychological tests did not reveal any evident or consistent pattern of
cognitive change in any of the patient groups.Most clinical data on cognitive function and
anti-hormonal therapy have been on selective estrogen receptor modulators (SERMS) such as
tamoxifen, although focus on aromatase inhibitors has been increasing in recent years. A
substudy (designated the CoSTAR trial) pooled subjects from the pre-existing National
Surgical Adjuvant Breast and Bowel Project (NSABP) Study of Tamoxifen and Raloxifene (STAR)
randomizing women =35 years old with increased risk of breast cancer by Gail model evaluation
to either tamoxifen or raloxifene.The substudy required women to perform an 83-minute
standardized test battery covering multiple domains. Outcomes on cognitive testing were
similar in both groups. In the landmark NSABP Breast Cancer Prevention Trial (P-1) which
included 13,388 women at increased breast cancer risk, treatment with 5 years of tamoxifen
resulted in a reduced risk of breast cancer by 49% relative to placebo.A separate report
documented results of the P-1 Symptom Checklist assessment encompassing a few self-report
domains spanning cognition, musculoskeletal pain, vasomotor symptoms, nausea, sexual
problems, bladder problems, body image and vaginal symptoms.The cognitive assessment included
questions related to concentration, forgetfulness, avoidance of social affairs, and tendency
towards accidents. There was little difference in cognitive dysfunction between groups.
Notably, for these 2 studies, evaluation was conducted during the period of active therapy.
To address this issue, a study by Paganini-Hill et al in a population-based case-control
study examined 1163 women between 55-75 years old diagnosed with primary breast
cancer.Previous tamoxifen users were classified as short-term users (<4 years) or long-term
users (=6 years) and were compared with never users. Women who had used tamoxifen for 4-5
years had more memory problems reported to their physician compared to never users (3.8% vs
1.5%, p=0.04), especially for women currently on tamoxifen. However, no differences were seen
among never and past users suggesting limited long-term sequelae. Even among the
premenopausal population on tamoxifen, significantly lower processing speeds which appeared
to interfere with executive functioning have been reported in a cross-sectional study
comparing women on adjuvant tamoxifen to healthy controls.Clinical data on the effects of
aromatase inhibitors on cognitive function are emerging. The largest dataset comes from the
International Breast Intervention Study II (IBIS II) studying postmenopausal women at
increased risk of breast cancer receiving either anastrozole or placebo for 5 years, testing
being done at 0, 6 and 24 months. No differences in cognitive function between the 2 groups
were detected. However the neurocognitive testing was done during the period of treatment as
in other previously described studies and in a postmenopausal hypoestrogenic population. As
such, the effects of AIs could have been blunted.In a substudy of the Anastrazole, Tamoxifen
and Combined (ATAC) trial which recruited patients with localized breast cancer to adjuvant
tamoxifen, anastrozole or combination therapy, 94 patients from the ATAC trial were compared
to 35 non-cancer controls. Their mean length of study time was 36 months. The patient group
was significantly impaired compared to the control group on measures of verbal memory
(p=0.026) and processing speed (p=0.032). Comparisons between anastrozole and tamoxifen have
been done in a cross-sectional and longitudinal study, both of which demonstrated the
anastrozole exposed group experiencing worse cognitive impairments.There were poorer verbal
and visual learning and memory in the study by Bender et al,44 while the prospective
longitudinal study showed a nine-fold and five-fold increase in risk of cognitive decline in
the anastrozole and tamoxifen groups respectively relative to healthy controls; the most
common domains affected being processing speed and verbal memory.A neuropsychological
substudy was carried out from the pivotal Tamoxifen and Exemestane Multinational (TEAM) trial
which randomized patients to adjuvant exemestane for 5 years or adjuvant tamoxifen for 2.5-3
years followed by exemestane for 2-2.5 years .The neuropsychological assessment was carried
out pre-endocrine therapy and after a year of treatment, and included 80 tamoxifen and 99
exemestane users. Interestingly, exemestane users did not perform statistically worse than
healthy controls on any cognitive domain, but tamoxifen users had significantly worse verbal
memory and executive functioning compared to healthy controls, and significantly worse
information processing speed compared to exemestane users. However, it has been postulated
that exemestane's mildly androgenic properties may ultimately preserve cognition.A recent
cognitive testing report of the Breast International Group (BIG)1-98 study randomizing women
to adjuvant monotherapy of tamoxifen or letrozole for 5 years, or sequential therapy with
letrozole followed by tamoxifen or vice versa revealed that women taking letrozole in the 5th
year had better overall cognitive function than those taking tamoxifen (p=0.04).A significant
improvement in composite cognitive function for both groups was observed in years 5-6 when
treatment was ceased. In summary, with repect to AIs, a greater cognitive decline has been
observed with anastrozole as compared to tamoxifen, while a lesser decline is seen with
exemestane and letrozole.Larger studies are clearly need to validate these findings. Results
from many of these studies need to be interpreted cautiously, as there have been various
limitations in studies pertaining to this field. Many studies have been hampered by a variety
of inherent methodological problems. These include lack of a baseline assessment, lack of a
longitudinal design, and failure to control for physical and psychosocial confounding factors
such as hormonal factors, depression, anxiety, fatigue and educational level.Furthermore,
studies have also differed considerably with respect to regimens and doses of chemotherapy
received, previous exposure to anti-hormonal therapy and length of time post-treatment. In
addition, a limitation of several studies is the lack of pre-treatment evaluations of
cognitive function.This is especially problematic because it makes it impossible to determine
whether deficits were present before treatment or to detect changes from baseline. The timing
of cognitive function assessment after the completion of therapy was also not uniform. Most
studies lacked non-treated comparison groups and failed to measure potential moderators of
cognitive function. Several studies failed to include a comprehensive assessment of the
multiple domains of cognitive function, and occasionally relied on the use of a self-report
questionnaire. Importantly, cognitive studies in the Asian population have been grossly
limited. Certain biological pathways, genetic polymorphisms and epigenetic changes could lead
to alterations in cognitive functioning in only a subgroup of people exposed to chemotherapy.
For example, several genetic polymorphisms of multidrug resistance 1 (MDR1) have been
identified that may influence P-glycoprotein (P-gp) function, one of the most studied
polymorphisms being C3435T in exon26.P-gp which is present in the blood brain barrier affects
the amount of drug uptake into the brain by actively transporting them out of the cells.
Polymorphisms associated with lower expression or functionality of P-gp may cause increased
vulnerability to chemotherapy-induced cognitive changes. Oxidative stress is the most
frequent cause of DNA damage in neuronal cells, and has been associated with various
neurodegenerative diseases including Alzheimer's and Parkinson's disease. DNA damage and
repair systems have been linked to neurodegeneration such as in ataxia telengectasia and
xeroderma pigmentosum. So far the relation of cognitive functions to the level of DNA damage
post-chemotherapy has not been well studied. As mentioned, certain studies have detected
higher than expected rates of cognitive impairment pre-chemotherapy. In addition higher
levels of oxidative DNA damage have been found in women with breast cancer.These data are
consistent with research linking certain DNA repair polymorphisms with a decreased DNA repair
capacity and thus an increased cancer risk. Hence, changes in cognitive function following
chemotherapy can be evaluated within the context of genetic factors that increase cancer risk
but also increase risk of cognitive dysfunction pre-treatment. Certain polymorphisms in the
base-excision pathway may also be worthwhile studying because of their importance in
modulating oxidative stress and cancer risk.Cytokines play a role in central nervous system
function, including modulation of neuronal and glial cell functioning, neural repair and
metabolism of dopamine and serotonin, which are important neurotransmitters for cognition.
Longitudinal studies of interferon-a and IL2 in cancer populations have shown decrements in
cognitive performance, particularly in the domains of information processing speed, executive
function, spatial ability and reaction time.Both chemotherapy and persistent fatigue have
been linked to increased cytokine levels.Genetic polymorphisms have been identified that
influence cytokine activity and are associated with Alzheimer's disease and depression.
However, so far the relationships between these polymorphisms and chemotherapy-induced
cognitive changes have not been well studied. The catechol-O-methyltransferase (COMT) valine
genotype has been linked to chemotherapy-related cognitive impairment in breast cancer
survivors and is worthwhile of further study. Chemotherapy in mouse models has also been
demonstrated to decrease hippocampal cell proliferation, increase histone acetylation and
decrease histone deacetylase activity. Hence, it would therefore be relevant to study the
particular candidate mechanisms which are likely to influence cognitive changes in certain
susceptible individuals. Inclusion of assessments of confounding factors which could play a
role in influencing cognitive function is vital. Fan et al in their study reported that
fatigue, menopausal symptoms and cognitive were important adverse effects of chemotherapy
that improved in most patient over a period of 1-2 years. In comparison, hormonal therapy had
minimal impact on them.But, even with the use of increasingly sophisticated performance-based
assessments, subtle differences are often being missed along with the obscurity of the neural
circuits and structures underlying the cognitive changes. For this reason, neuro-imaging
tools have gained advantage because they provide the opportunity to examine the effects of
chemotherapy on brain and cognition. However, such studies have been very limited in the
field and therefore the need for further brain imaging studies. MRI has emerged as a
noninvasive method with the potential to produce high resolution and contrast images of the
brain. From the anatomical findings, adjuvant chemotherapy was associated with long-term
injury to white matter and also damage to gray matter with associated functional deficits. An
early study by Inagaki et al. comparing 51 adjuvant chemotherapy treated breast cancer
patients with 55 patients who did not receive chemotherapy, showed that chemotherapy patients
had smaller volumes in key areas involved in cognitive processing. The patients showed a
strong positive correlation between volume loss and performance on the WMSR (Wechsler Memory
Scale Revised) test of attention and memory. A serious weakness of this study was the failure
to consider the effect of adjuvant endocrine therapy and the lack of prechemotherapy baseline
assessment. Only three studies to date have investigated the integrity of white matter tracts
and structural connectivity using diffusion tensor imaging (DTI). Results revealed structural
neural changes over time as well as indicated region specific differences inherent to most of
the cognitive deficits.The corpus callosum, an area important for communication between
hemispheres, exhibited reduced white matter integrity which may explain the reduced
processing speed reported in the chemotherapy-treated patients. The effect of endocrine
treatment was not considered in the analysis which provides a drawback for proper
interpretation. Another study showed decreased Fractional Anisotropy (FA) in frontal and
temporal white matter tracts as well as increased Mean Diffusivity (MD) in frontal white
matter. A significant correlation was also seen between the FA scores and the
neuropsychological tests (attention and processing speed) in the chemotherapy-treated
patients. White matter organization, particularly in the frontal, parietal and occipital
white matter tracts, was negatively impacted by chemotherapy and this correlated strongly
with cognitive functioning scores. This suggests that microstructural white matter changes or
abnormalities may underlie reported cognitive dysfunctions found in chemotherapy treated
cancer patients, especially that cerebral white matter is vulnerable to neurotoxins.In
addition to the small number of structural imaging studies, a limited number of functional
imaging studies have assessed neural changes in chemotherapy treated cancer patients.
Combining the anatomical/structural assessment with functional imaging techniques provides a
wider window of evaluation onto the functional changes associated with such cognitive
deficits. To understand the underlying functional changes associated with poor executive
function and processing in chemotherapy patients, a study by Saykin et al was one of the
first to incorporate working memory assessments with functional MRI readouts. This was one of
the first prospective longitudinal studies comparing pre- and post-treatment on a working
memory N-back task. Although the authors reported no group differences in task performance
with the expected main effect of working memory load on performance at baseline, patients
assessed one month post-chemotherapy showed increased activation in posterior frontal and
parietal regions compared to controls with less bilateral activity in more anterior frontal
regions. This study illustrates that the cognitive changes associated with chemotherapy may
be too subtle to reliably be detected with standard neuropsychologial assessments and
underscore the importance of and potential for using functional MRI to elucidate underlying
neurobiological changes.Interestingly, while investigating declarative memory in 14 breast
cancer patients three years following chemotherapy, patients showed less activity in
bilateral frontal gyri and postcentral gyrus with greater activation in parahippocampal,
bilateral cerebellum, cingulate and precuneus while exhibiting normal cognitive assessment
and cortisol levels (a measure of distress) compared to control. The increased activation in
several brain areas compared to controls indicates that patients required greater and more
global neural effort than controls when attempting to recall task information. More
interestingly, this study showed that the type of chemotherapy regimen contributed to
differential patient verbal memory impairments; CMF treated patients showed lower prefrontal
cortex activity during encoding compared to patients on the
adriamycine/cyclophosphamide/taxol regimen. This indeed highlights the importance of
distinguishing between different types of chemotherapy treatment. Although functional MRI is
the gold standard for evaluation of brain function, it is an indirect measure and functional
readouts do not represent the underlying neuronal mechanisms involved. Other methods have
been investigated to assess mere brain activity and more directly detect the underlying
mechanism of cognitive dysfunction in chemotherapy patients. Only two PET (Positron Emission
Tomography) imaging studies have been conducted to date. A recent study was conducted in 5
year post-chemotherapy patients. Patients exhibited lower resting metabolism in the frontal
cortex and basal ganglia. A major drawback of this study was the lack of baseline assessment
and the inhomogeneous study group where eight of the patients were on tamoxifen
treatment.Another PET/CT study to assess brain metabolism after chemotherapy in 128 patients
is still ongoing.Results from many of these studies need to be interpreted cautiously, as
there have been various limitations in studies pertaining to this field. Many studies have
been hampered by a variety of inherent methodological problems. These include lack of a
baseline assessment, lack of a longitudinal design, and failure to control for physical and
psychosocial confounding factors such as hormonal factors, depression, anxiety, fatigue and
educational level. Furthermore, studies have also differed considerably with respect to
regimens and doses of chemotherapy received, previous exposure to anti-hormonal therapy and
length of time post-treatment. In addition, a limitation of several studies is the lack of
pre-treatment evaluations of cognitive function. This is especially problematic because it
makes it impossible to determine whether deficits were present before treatment or to detect
changes from baseline. The timing of cognitive function assessment after the completion of
therapy was also not uniform. Most studies lacked non-treated comparison groups and failed to
measure potential moderators of cognitive function. Several studies failed to include a
comprehensive assessment of the multiple domains of cognitive function, and occasionally
relied on the use of a self-report questionnaire. Importantly, cognitive studies in the Asian
population have been grossly limited. Taking these shortcomings into consideration, we
designed a study intended to minimise biases mentioned as above. The chemotherapy regimen
utilised will be limited to that of anthracyclines and taxanes; specifically we will use
patients given doxorubicin/cyclophosphamide (AC) for 4 cycles followed by weekly paclitaxel
for 12 cycles as per the adjuvant breast cancer study by Sparano et al as this is the
chemotherapy regimen most commonly used in our division. Furthermore, we will have a baseline
pre-treatment assessment for both CANTAB and imaging assessments, a longitudinal study
design, and a more uniform evaluation taking 6 months and one year post-chemotherapy or after
starting one year of anti-hormonal therapy as a cut-off point for CANTAB and imaging
assessments. We will also attempt to minimize biases by analyzing confounders such as
anxiety, depression and hormonal fluctuations using questionnaires and also recruit a control
group of healthy subjects with similar age, gender and social background.
