The development of anticipatory nausea in patients receiving adjuvant chemotherapy for breast cancer

D2 Receptors and Sodium Ion Channel Blockades of the Basolateral Amygdala Attenuate Lithium Chloride-Induced Conditioned Taste Aversion Applying to Cancer Chemotherapy Nausea and Vomiting

Cancer patients regularly suffer from the behavioral symptoms of chemotherapy-induced nausea and vomiting. Particularly, it is involved in Pavlovian conditioning. Lithium chloride (LiCl) was used as the unconditioned stimulus (US) and contingent with the tastant, for example, a saccharin solution (i.e., the conditioned stimulus; CS), resulted in conditioned taste aversion (CTA) to the CS intake. The present study employed an animal model of LiCl-induced CTA to imitate chemotherapy-induced nausea and vomiting symptoms. Recently, the basolateral amygdala (BLA) was shown to mediate LiCl-induced CTA learning; however, which brain mechanisms of the BLA regulate CTA by LiCl remain unknown. The present study was designed to test this issue, and 4% lidocaine or D2 blocker haloperidol were microinjected into BLA between the 0.1% saccharin solution intake and 0.15M LiCl. The results showed lidocaine microinjections into the BLA could attenuate the LiCl-induced CTA. Microinjections of haloperidol blunted the CTA learning by LiCl. Altogether, BLA via the sodium chloride ion channel and D2 receptors control LiCl-induced conditioned saccharin solution intake suppression. The findings can provide some implications and contributions to cancer chemotherapy-induced nausea and vomiting side effects, and will help to develop novel strategies to prevent the side effects of cancer chemotherapy.

Endocannabinoid Mechanisms Influencing Nausea

One of the first recognized medical uses of Δ(9)-tetrahydrocannabinol was treatment of chemotherapy-induced nausea and vomiting. Although vomiting is well controlled with the currently available non-cannabinoid antiemetics, nausea continues to be a distressing side effect of chemotherapy and other disorders. Indeed, when nausea becomes conditionally elicited by the cues associated with chemotherapy treatment, known as anticipatory nausea (AN), currently available antiemetics are largely ineffective. Considerable evidence demonstrates that the endocannabinoid system regulates nausea in humans and other animals. In this review, we describe recent evidence suggesting that cannabinoids and manipulations that enhance the functioning of the natural endocannabinoid system are promising treatments for both acute nausea and AN.

Role of classical conditioning in learning gastrointestinal symptoms

Nausea and/or vomiting are aversive gastrointestinal (GI) symptoms. Nausea and vomiting manifest unconditionally after a nauseogenic experience. However, there is correlative, quasiexperimental and experimental evidence that nausea and vomiting can also be learned via classical (Pavlovian) conditioning and might occur in anticipation of the nauseogenic event. Classical conditioning of nausea can develop with chemotherapy in cancer patients. Initially, nausea and vomiting occur during and after the administration of cytotoxic drugs (post-treatment nausea and vomiting) as unconditioned responses (UR). In addition, 20%-30% of cancer patients receiving chemotherapy report these side effects, despite antiemetic medication, when being re-exposed to the stimuli that usually signal the chemotherapy session and its drug infusion. These symptoms are called anticipatory nausea (AN) and/or anticipatory vomiting (ANV) and are explained by classical conditioning. Moreover, there is recent evidence for the assumption that post-chemotherapy nausea is at least partly influenced by learning. After summarizing the relevant assumptions of the conditioning model, revealing that a context can become a conditioned stimulus (CS), the present paper summarizes data that nausea and/or vomiting is acquired by classical conditioning and, consequently, may be alleviated by conditioning techniques. Our own research has focussed on two aspects and is emphasized here. First, a conditioned nausea model was established in healthy humans using body rotation as the nausea-inducing treatment. The validity of this motion-sickness model to examine conditioning mechanisms in the acquisition and alleviation of conditioned nausea and associated endocrine and immunological responses is summarized. Results from the rotation-induced motion sickness model showed that gender is an important moderator variable to be considered in further studies. This paper concludes with a review of the application of the demonstrated conditioning principles as interventions to ameliorate distressing AN/ANV in cancer patients undergoing chemotherapy, which is the second focus of our work.

Anticipatory Nausea: The Role of Individual Differences Related to Sensory Perception and Autonomic Reactivity

BACKGROUND

Anticipatory nausea (AN) during chemotherapy has been difficult to control with conventional antiemetics. AN can lead cancer patients to delay or discontinue chemotherapy, possibly compromising the treatment.

PURPOSE

The aim is to investigate the possible influence on the development of AN of individual differences in absorption, somato-sensory amplification, and autonomic perception-measures theorized to be related to sensory perception and autonomic reactivity.

METHODS

Prior to treatment, 125 women (M age = 48.5 years) undergoing adjuvant chemotherapy for breast cancer rated their expected severity of side effects and completed the Tellegen Absorption Scale, the Somato-Sensory Amplification Scale, and the Autonomic Perception Questionnaire. AN, as well as anticipatory vomiting (AV), distress, and worry/anxiety, were measured prior to the fourth, sixth, and last cycle of chemotherapy. Posttreatment nausea (PN), vomiting, and fatigue were measured after the first, fourth, sixth, and last cycle.

RESULTS

34% of the women reported AN before 1 or more cycles. When controlling for treatment characteristics and other known predictors, AN was significantly associated with high absorption in addition to severity of PN, pretreatment worry/anxiety, and not receiving radiotherapy between chemotherapy sessions. AV was not associated with any of the variables investigated. Our data suggest that the association is strongest in the early phases of treatment.

CONCLUSIONS

Our results partly confirm the results of a previous study showing absorption and autonomic perception as predictors of anticipatory side effects in cancer patients receiving chemotherapy. Individuals high in absorption may be more autonomically reactive to aversive stimuli and, subsequently, more conditionable. Additional radiotherapy could be a competing stimulus, reducing the conditioning of chemotherapy-related nausea. Further studies investigating possible psycho-physiological mechanisms in the development of AN are needed.

The continuing problem of post chemotherapy nausea and vomiting: contributions of classical conditioning

Despite continuing improvements in antiemetic therapies, nausea and vomiting following chemotherapy treatments for cancer remain significant clinical problems for many patients. The role of classical conditioning in patients' anticipatory nausea is well known, but little attention has been paid to possible conditioning effects on post treatment nausea. The present study statistically examined the contribution of anticipatory (conditioned) nausea to patients' subsequent post treatment nausea. Forty early stage breast cancer patients who developed anticipatory nausea were analyzed. Results revealed a significant correlation between the intensity of anticipatory nausea in the clinic prior to their treatment infusion and subsequent post treatment nausea during the 24 h after the infusion. These results provide support for the hypothesis that, once established, conditioned nausea may contribute to the severity of subsequent post treatment nausea in patients receiving repeated cycles of chemotherapy for cancer. The results suggest the importance of considering the contribution of conditioning process to nausea and other post treatment side effects.

Evidence for Classically Conditioned Fatigue Responses in Patients Receiving Chemotherapy Treatment for Breast Cancer

Fatigue is the most common side effect of chemotherapy for cancer. Not yet explored is the possibility that patients may develop conditioned fatigue responses to clinic cues as a result of the repeated pairing of the clinic environment (conditioned stimulus) with infusions of chemotherapy (unconditioned stimulus) that cause fatigue (unconditioned response). As a first critical test of this possibility, breast cancer patients (N = 82) were studied across their first four cycles of chemotherapy. Consistent with conditioning: (1) fatigue levels in the clinic environment significantly increased with repeated pairings of the clinic environment and chemotherapy administration; (2) fatigue responses in the clinic environment prior to the fourth infusion (CR) were predicted by patients' previous experiences of post-infusion fatigue (UR) above and beyond effects of concurrent emotional distress. These results provide the first evidence in the literature that fatigue can be conditioned. Additional research is warranted to determine the clinical importance of this source of fatigue in chemotherapy patients.

Presurgery distress and specific response expectancies predict postsurgery outcomes in surgery patients confronting breast cancer

Prior to scheduled surgery, patients frequently experience particularly high levels of distress and expect a variety of postsurgery symptoms. Surgery patients who confront breast cancer are no exception. It has been suggested that such presurgery distress and response expectancies are predictive of postsurgery outcomes. To test the contribution of presurgery distress and expectancies to common postsurgery symptom outcomes (pain, nausea, fatigue, and discomfort), 63 female patients undergoing breast cancer surgery were recruited to a prospective study. Results indicated that presurgery distress uniquely contributed to patients' postsurgery nausea, fatigue, and discomfort; specific expectancies uniquely contributed to pain intensity, pain unpleasantness, and fatigue (ps < .05). Consistent with expectancy theory, associations between response expectancies and postsurgery outcomes were not due to presurgery distress.

Expectations of chemotherapy-related nausea: emotional and experiential predictors

Despite literature indicating that expectations are important determinants of experiences of nonvolitional outcomes (e.g., pain, nausea), little research has explored their source. The dual process model suggests that concurrent experience of emotional distress should be a strong contributor, whereas social learning theory supports the position that expectations of nonvolitional outcomes should be based primarily on prior experience. These alternative hypotheses were tested in a sample of 80 breast cancer patients undergoing outpatient adjuvant chemotherapy, as such protocols provide a unique opportunity to study the impact of emotional distress and prior experience on patients' expectations of side effects. Bivariate analyses suggested that emotional distress contributed early in the course of treatment, but once prior experience of posttreatment nausea (PTN) was accounted for in the statistical model, distress no longer made significant contributions to patients' expectations of PTN, whereas prior experience did (p < .001). These findings suggest that experience of chemotherapy infusions is an important source of expectations for PTN, which may be representative of the source of expectations for nonvolitional outcomes in broader contexts.

The role of behavioral conditioning in the development of nausea

Literature related to the prevalence and etiology of anticipatory nausea and vomiting associated with chemotherapy is reviewed. Physiologic causes and psychological factors, including expectations, beliefs, and conditioning, are examined to help explain these phenomena. The efficacy of pharmacologic and behavioral treatments is discussed. Similarities between the experience of anticipatory nausea and vomiting and morning sickness suggest that the conditioning model may be relevant to understanding the development of pregnancy-related nausea.

The role of patients' expectations in the development of anticipatory nausea related to chemotherapy for cancer

Although anticipatory nausea (AN), which is reported by one-third of patients receiving chemotherapy for cancer, is thought to develop primarily by classical conditioning, response expectancies may also be important. The role of patients' expectations of nausea in the development of AN was examined in 63 female cancer patients receiving their first course of chemotherapy. Twenty women (32%) expected to experience nausea and twelve (19%) reported AN before the third cycle. Pretreatment expectations predicted AN at cycle three (Spearman's r = 0.41, P = 0.001). AN developed in 40% of patients who expected nausea, 13% of those who were uncertain whether they would develop it, and no patients who did not expect nausea. Logistic regression indicated that expecting nausea was the strongest predictor (chi(2) =13.15; P < 0.001). Results support a role for cognitive factors in the development of chemotherapy side effects and suggest testing psychologic interventions to modify patients' expectations.

Specific response expectancies predict anticipatory nausea during chemotherapy for breast cancer

Clinical research has demonstrated that large numbers of chemotherapy patients continue to experience nausea in the clinic prior to infusions. A better understanding of the mechanisms responsible for such anticipatory nausea (AN) is likely to provide critical information for identifying intervention targets. In the present study the authors investigated the contribution of expectancy, history of nausea, and distress to AN in 60 women with Stage I or II breast cancer receiving standard adjuvant chemotherapy. The predictors were each independently associated with AN (p < .05). However, only expectations significantly predicted AN in simultaneous regression analyses. Results suggest that interventions to reduce AN during chemotherapy should target patients' expectations.

Effects of overshadowing on conditioned nausea in cancer patients: an experimental study

The infusion of cytotoxic drugs in cancer patients is often accompanied by posttreatment nausea (PN). In addition, patients complain about nausea prior to an infusion [i.e., anticipatory nausea (AN)]. AN is mainly explained by classical conditioning, with the infusion as the unconditioned stimulus (US) and with the stimuli signaling the infusion as conditioned stimuli (CS). Despite this conditioning etiology, a specifically derived therapy to attenuate the CS-US contingency is missing. The purpose of this study is to develop and to test an overshadowing procedure for prevention of AN, and also for the modification of PN intensity. Sixteen cancer patients were assigned to one of two groups: Overshadowing+ (OV+) and Overshadowing- (OV-). At the start of all infusions of two consecutive chemotherapy cycles A and B (acquisition), OV+ subjects drank a saliently tasting beverage (the overshadowing CS), whereas group OV- drank water. All patients received water in cycle C (test). Self-reported symptoms and heart rates were recorded. As expected, in cycle C (test), no patient of group OV+ showed AN, whereas two patients of group OV- developed AN. There was a tendency for a reduction of the intensity of PN, in terms of duration and latency after overshadowing, in cycle C: OV+ patients tended to show a shorter duration and a longer latency between end of infusion and PN onset. In OV-, there was a significantly larger heart rate deceleration in both measurement periods, in the anticipatory and the posttreatment measurement period. Data suggest to apply overshadowing for prevention of AN and modification of PN. Physiological markers of conditioned nausea are revealed. After its procedural implementation, the technique can be used in larger samples now.