a prior cycle of chemotherapy,
and alcohol intake. Individual
genetic variants resulting in
differences in the structure
of the serotonin receptors, as
well as in the metabolism of
the receptor antagonists and
cellular transport of antiemetic
agents, might also contribute to
variations in risk of emesis, but
these pharmacogenomic aspects
have not been fully investigated
in clinical trials. Moreover, type
of chemotherapy (that is, use
of drugs with high or medium
emetogenicity potential) and
adherence to antiemetic therapy
can also successfully predict the
occurrence of CINV (Table 1). 5
Nonetheless, delayed symptoms
of CINV pose particular challenges
to the oncology team. Although it
is well known that patients who
experience acute symptoms have
a higher risk of also developing
delayed CINV, studies of risk
factors in this specific context
are scarce. A prospective,
observational, multicentre study
conducted in Canada evaluated
patients with cancer who were
initiating chemotherapy, either for
the first time or a new regimen,
and who received standard
antiemetic therapy whenever
needed. Young age (<40 years
old), reporting acute emesis after
chemotherapy, use of over-the-
counter medication to alleviate
emesis, post-chemotherapy use of
dexamethasone (with or without
ondansetron), and history of
nausea/vomiting or morning
sickness during pregnancy were
statistically significant predictors
of delayed CINV. By contrast, a
lower risk for developing these
symptoms was seen for patients
who slept more hours prior to
their chemotherapy session (which
is considered to be a surrogate for
anxiety levels) and after the two
cycles of chemotherapy. 6
Additionally, nausea and
vomiting can occur before a
chemotherapy session. These
anticipatory symptoms are
more frequently observed in
later cycles of treatment and are
usually refractory to antiemetic
therapy, constituting a risk factor
for CINV that cannot simply be
ignored. Patients at a higher
risk of developing anticipatory
nausea and vomiting symptoms
include young patients and
women, those previously reporting
motion sickness, patients with
negative expectations in regard
to CINV, and, in particular, those
experiencing CINV during prior
chemotherapy cycles. However, it
is not known if these anticipatory
symptoms are currently assessed
by physicians on a regular basis
in their practice. Psychological
factors are certainly at play and
can be controlled by cognitive
behavioural therapy and the use
of benzodiazepines for the relief
of anxiety. However, anticipatory
nausea and vomiting events
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