Cancer Centre Singapore Research Articles

3072 POSTER Impact of Adherence to Antiemetic Regimens on Outcome of Nausea and Vomiting Control Among Asian Breast Cancer Patients Receiving Anthracycline-based Chemotherapy

Background: Non-adherence to oral anticancer agents has been identified as a prevalent behavior amongst breast cancer patients. However, the prevalence of non adherence to outpatient antiemetic regimens that are prescribed for delayed emesis prevention in breast cancer patients is limited in the literature. Hence, this study was conducted to evaluate the impact of adherence to delayed antiemetic regimens on chemotherapy induced nausea and vomiting (CINV) control in breast cancer patients, and to identify patient characteristics that may be associated with non-adherence to antiemetic regimens. Methods: This was a prospective, observational study conducted at the largest ambulatory cancer center in Singapore from December 2006 to January 2011. All breast cancer patients receiving anthracycline-based chemotherapy and standardized outpatient antiemetic regimens were recruited. On the day of chemotherapy, patients were given a standardized 5-day diary to document their emesis events and their demographics obtained via interview. Pearson Chi-square test and multiple logistic regression were performed to analyze the impact of adherence on CINV control. Results: A total of 361 eligible patients were included in the final analysis (mean = 50.0±8.9 years). Majority of the patients were Chinese (80.1%) and diagnosed with Stage 2 and above breast cancer (88.1%). Almost half of the patients (42.1%) were non-adherent to their prescribed delayed antiemetics regimens, with dexamethasone usage being the least adhered to (non adherence: 37.4%). After adjusting for potential confounders (ethnicity, education level and stage of disease), patients who were adherent to antiemetics were more likely to achieve complete CINV control (defined as no emetic episodes, no nausea, and no rescue therapy required) than patients who were non adherent (NNT=9.6; Adjusted OR=1.74, 95% CI: 1.01 3.01). In addition, young women aged between 21−40 years old, pursued higher education, and diagnosed with Stage 1 breast cancer were associated with non adherence to antiemetics (p < 0.05). Conclusion: This is the largest study to date to evaluate the prevalence of non-adherence to delayed antiemetics among breast cancer patients. Our findings indicate that a substantial amount of Asian breast cancer patients (42.1%) were not adherent to their antiemetic regimens, which may have resulted into poor control of CINV.

Electronic database to detect drug–drug interactions between antidepressants and oral anticancer drugs from a cancer center in Singapore: implications to clinicians

Electronic drug interaction databases are often utilized in clinical practice to detect for possible drug-drug interactions between drug pairs. It is uncertain, however, whether most of these detections interactions are clinically important in practice. To demonstrate these issues, this study utilized a comprehensive drug-drug interaction (DDI) electronic database to elucidate the prevalence of DDIs at a cancer centre between antidepressants and oral anticancer drugs (ACDs). Drug utilization reports were retrieved to determine the patients who were prescribed with antidepressants oral ACDs between 2006 and 2009 at a cancer center. Medication records of these patients were retrospectively examined using OncoRx, an internet-based oncology-specific database that allows the identification of DDIs. Out of 910 users of antidepressants, about one-third (281 patients, 30.9%) used an oral ACD and an antidepressant concomitantly. From these patients, about one-fifth (21.0%) had potential DDIs. These patients were users of 17 potentially interacting drug pairs. Ten out of the 17 drug pairs could potentially cause pharmacokinetic interactions, and the rest were pharmacodynamic interactions, with only three out of the 17 drug pairs were clinically documented to cause interacting events. The lack of screening conditions may have led to an over detection of DDI combinations by electronic DDI databases. Many of the detected interactions may not deem high significance in clinical practice. This study exposed a major weakness of current electronic DDI databases for detecting oral ACDs and antidepressants DDIs.

Epidermal growth factor receptor (EGFR) mutation testing and first-line treatment with gefitinib as a strategy in the treatment of patients with advanced non-small cell lung cancer (NSCLC).

7598 Background: Gefitinib improves response rates, progression-free survival and quality of life (QOL) when compared to chemotherapy in patients with advanced NSCLC who have activating EGFR mutations. Yet, little is known about the cost-effectiveness (CE) of this approach Methods: A decision-analytic model was developed to determine the CE of EGFR testing and guided therapy with 1st line gefitinib for patients with activating mutations (and 1st line chemotherapy and no gefitinib for patients without) vs. standard care: first line chemotherapy and gefitinib at progression in unselected patients. Clinical data are derived from published randomized clinical trials and costs for drugs, visits, tests and treatment of adverse events from cancer centers in Singapore with a societal perspective in 2010 Singapore dollars (S$). Quality-adjusted life years (QALY) gained and incremental cost-effectiveness ratios (ICER) were calculated. Sensitivity analyses were conducted Results: EGFR testing and 1st line treatment with gefitinib is a dominant strategy (it has lower costs and greater effectiveness) compared to no testing, 1st line chemotherapy and 2nd line gefitinib in unselected patients. Because the main savings in the testing arm result from not providing gefitinib to those who do not benefit, this finding holds regardless of the prevalence of patients with activating mutations. In a secondary analysis, 1st line gefitinib was also dominant when compared to 1st line chemotherapy in patients with activating EGFR mutations, primarily due to better QOL. In a scenario in which patients did not receive second line gefitinib in the standard arm, the ICER for EGFR testing and guided treatment with gefitinib was below S$ 78,000/QALY (1.3 S$ = 1 US$) Conclusions: Based on these data, EGFR testing and first line treatment with gefitinib for patients with activating mutations should become the standard treatment in advanced NSLC. In this era of exponentially increasing costs, the use of biomarkers may improve patient selection and the CE of new therapies.

Unmet psychosocial needs among cancer patients undergoing ambulatory care in Singapore

Previous studies have demonstrated high prevalence of unmet psychosocial needs among cancer patients, but few were conducted among Asians. In this cross-sectional study, we investigated the prevalence of and factors associated with unmet psychosocial needs among cancer patients undergoing ambulatory care at a cancer centre in Singapore. We conducted a cross-sectional study among 535 breast, gynaecological and colorectal cancer patients (response rate, 76%) using a modified version of the Cancer Survivors' Unmet Needs measure questionnaire, to assess the prevalence of patients' needs for disease information and social support, physical needs, financial needs and psychological needs, and the extent to which needs were met. Logistic regression analysis was used to identify demographic or disease characteristics associated with unmet needs. Seventy-five per cent of patients reported having any unmet needs, with disease information needs being most prevalent (61.5%) followed by financial (40.2%), social support (39.7%), psychological (27.3%) and physical (26.1%) needs. Factors independently associated with having high level of unmet needs were age below 60 years, ethnic minority, advanced disease and recent diagnosis. The prevalence of unmet psychosocial needs among cancer patients in ambulatory care is generally high. Young patients with disease recently diagnosed at advanced stage will benefit from additional support.

Clinical predictors for emesis in breast cancer patients receiving anthracycline-based chemotherapy: Do Asians measure up?

e19603 Background: In a post hoc analysis of 856 breast cancer patients (majority Caucasians) receiving anthracycline-based chemotherapy (Warr et al., MASCC 2009), patient characteristics, including young age, low alcohol consumption, and history of morning sickness, were associated with higher risks for emesis (E). However, whether these risk factors predict for E in the Asian population is unknown. This is the largest study to date that establishes the association of these predictors in a similar treatment cohort of Asian cancer patients through analysis of E events. Methods: This is a prospective, observational study conducted at the largest cancer center in Singapore from 2006 to 2009. On the day of chemotherapy, patients' demographics were retrieved via interview. They were also given a standardized 5-day diary to document their E events. Multiple logistic regressions were used to analyze the impact of these predictors on acute and delayed E. Results: 244 eligible women (mean 50 ± 8.9 years) were recruited. Incidences of acute and delayed E were 23.5% and 25.4% respectively. Multivariate analysis showed that young age (OR=2.13, 95%CI 1.13-4.02), histories of motion sickness (OR=2.44, 95%CI 1.17-5.08) and chemotherapy-induced E (OR=2.95, 95%CI 1.20-7.26) were significantly associated with increased likelihoods of acute E, while the latter two predictors were also significantly associated with increased likelihoods of delayed E (OR=2.29, 95%CI 1.13-4.64 and OR=2.42, 95%CI 1.03-5.69 respectively). Conclusions: In Asians, histories of motion sickness and chemotherapy-induced E are important predictors, but alcohol history and history of morning sickness are less likely to play a role. Clinicians should aware of the differences in E predictors between Asians and non-Asians. Multivariate analysis of emesis events Warr et al. (N = 856) Current study (N = 244) Overall emesis Acute emesis Delayed emesis Predictors p value p value p value Young age 0.006 0.02 NS Alcohol history (+) 0.0048 NS NS Morning sickness (+) 0.0007 NS NS Motion sickness (+) NS 0.02 0.02 History of chemotherapy-induced emesis NA 0.02 0.04 Abbreviations: NS, not statistically significant (p > 0.05); NA, not available. No significant financial relationships to disclose.

Clinical Predictors of Chemotherapy-Induced Nausea and Vomiting in Breast Cancer Patients Receiving Adjuvant Doxorubicin and Cyclophosphamide

Patients with breast cancer often receive emetogenic anthracycline-based chemotherapy as part of their treatment. Chemotherapy-induced nausea and vomiting (CINV) has been commonly reported as one of the distressing adverse effects among patients with cancer. Despite the advent of newer antiemetics and better understanding of the CINV pathophysiology, total eradication of CINV has yet to be achieved. To assess the incidence of nausea and vomiting in patients who have breast cancer and are receiving adjuvant doxorubicin and cyclophosphamide (AC) bolus chemotherapy, ascertain patients' risk factors affecting CINV response, and study patient adherence to delayed antiemetics. This was a single-institution, prospective, observational study conducted at an outpatient cancer center in Singapore from December 2006 to December 2007. Clinical events such as CINV were collated using a standardized diary. Use of rescue antiemetics and unscheduled clinic visits due to CINV were documented. Of a total of 108 participants, 16 patients were lost to follow-up and 1 provided incomplete information; thus, 91 patients were included in the analysis. Delayed antiemetics were given according to the institution's guideline and only 9 (9.9%) patients received aprepitant. Neither acute nor delayed vomiting was reported by a majority of patients and only 4 (4.4%) experienced grade 3 vomiting. The incidence of severe nausea was highest on day 3 of chemotherapy and affected 14.3% of patients. Anxiety and history of chemotherapy-induced nausea were associated with both acute and delayed nausea, and history of motion sickness was associated with delayed vomiting. Approximately 65% of patients were adherent to their prescribed delayed antiemetics. Most of our patients adhered to their antiemetics and tolerated AC chemotherapy reasonably well, without vomiting; yet nausea persisted. To improve CINV control, clinicians must actively communicate with patients to facilitate accurate assessment of risk factors and CINV response and to encourage adherence to delayed antiemetics.

Patients’ perspectives and safe handling of oral anticancer drugs at an Asian cancer center

Background. In view of the increased usage of oral anticancer drugs in the contemporary treatment of cancer, we aimed to examine cancer patients' perspectives of oral anticancer drugs, through a survey at an Asian cancer centre. This study also intended to describe patients' behavior regarding storage, handling, and administration of oral anticancer drugs. This cross sectional survey was conducted at a single site. The interviewer-administered survey was undertaken at the outpatient pharmacy of National Cancer Centre Singapore (NCCS), the largest ambulatory cancer center in Singapore, between January and March 2008. Eligible patients had received at least one cycle of oral anticancer agent treatment or had been taking oral anticancer agents continuously for 3 months. A total of 126 patients were surveyed. Median age of surveyed patients was 58 years (range 31-85 years). The drugs involved were capecitabine (39.7% of patients), tamoxifen (23.1%), aromatase inhibitors (18.2%), gefitinib (9.1%), and imatinib (3.3%). Over 90% patients self-administered their oral anticancer drugs. The majority of the patients (94.2%) reported no difficulties in adherence to their oral anticancer treatment regimens. Forty per cent of patients reported habitually washing their hands after administering their anticancer drugs. None of the patients, except two patients receiving capecitabine, indicated that they habitually used gloves to handle their oral anticancer medications. The majority of patients receiving oral anticancer agents reported no difficulty in adhering to their oral anticancer treatment regimens as prescribed. However, this survey demonstrated the need to improve patients' understanding of the requirements for storage, handling and safe administration of oral anticancer drugs.