Plain English Summary
Background and study aims
Breast cancer is the most prevalent cancer in women in Hong Kong and worldwide. After treatment such as surgery and chemotherapy, disease recurrence remains a significant concern. Nowadays, a common practice to prevent recurrence is to have women on adjuvant tamoxifen, a hormonal therapy, for 5 years. The relapse rate at 5 years for patients who adhere to adjuvant tamoxifen is significantly lower than for those women who discontinue the drug. However, among patients who receive adjuvant tamoxifen treatment, individual responses are highly variable. These variable responses include the type, frequency and severity of endocrine symptoms and reduced tamoxifen adherence, which ultimately affect the cancer recurrence rate. Polymorphisms (genetic variations) in some genes involved in the metabolism of tamoxifen are likely to influence these detrimental responses to tamoxifen. This study aims to characterize the genetic polymorphisms of tamoxifen metabolism-associated genes in Chinese women with breast cancer and to explore the inter-relationships between genetic polymorphisms, endocrine symptoms, and adherence to tamoxifen that could affect the effectiveness of treatment.
Who can participate?
Chinese women with breast cancer treated with surgery and chemotherapy and started on tamoxifen within the past month
What does the study involve?
A questionnaire consisting of demographics, health status details, assessment of endocrine symptoms and drug adherence is completed at the start of the study and after 3, 6, 9 and 12, 15, and 18 months by phone interview. At 12 and 18 months, information on breast cancer recurrence is collected. A saliva sample is also collected from the participants at the start of the study to test for genetic polymorphisms. Participants keep a medication log book to record their intake of tamoxifen, supplements, Chinese herbal medicine, and other medications on a daily basis. The surveys are completed anonymously.
What are the possible benefits and risks of participating?
There are no risks and benefits expected from the study.
Where is the study run from?
Chinese University of Hong Kong and Prince of Wales Hospital (Hong Kong)
When is the study starting and how long is it expected to run for?
November 2016 to August 2021
Who is funding the study?
Chinese University of Hong Kong (Hong Kong)
Who is the main contact?
Prof. Carmen Wing Han Chan
Prof Carmen Wing Han Chan
Esther Lee Buidling
The Chinese University of Hong Kong
Identification of predictive biomarkers for tamoxifen-related endocrine symptoms and drug adherence based on genetic polymorphisms in Chinese patients with breast cancer: a prospective pilot study
1. There is a relationship between the severity of tamoxifen-induced endocrine symptoms and allelic variations in tamoxifen metabolism-related genes
2. Patients with more severe endocrine symptoms (psychological, vasomotor, somatic or sexual) are less likely to adhere to tamoxifen
Approved 01/12/2016, The Joint Chinese University of Hong Kong – New Territories East Cluster Clinical Research Ethics Committee (8/F, Lui Che Woo Clinical Sciences Building, Prince of Wales Hospital, Shatin, Hong Kong; Tel: +852 (0)35053935; Email: firstname.lastname@example.org), Approval #2016.554
Prospective cohort study
Primary study design
Secondary study design
Quality of life
Patient information sheet
This prospective cohort study will recruit patients from the Department of Clinical Oncology in Prince of Wales Hospital in Hong Kong. Self-reported endocrine symptoms and the saliva of patients will be collected at enrolment. At 3, 6, 9, 12, 15, 18 months after enrolment, data on symptoms and drug adherence will be collected by phone interview using the same measures. Data collection will stop at 18 months because symptoms of tamoxifen therapy appear early and are worst during the first 12 months after the initiation of treatment. Patients’ saliva will be collected during enrolment for the single nucleotide polymorphism (SNP) evaluation of genes associated with drug metabolism enzymes and transporters.
Primary outcome measure
Endocrine symptoms measured using the Greene Climacteric Scale (GCS) and the Functional Assessment of Cancer Therapy-Endocrine subscale (FACT–ES) questionnaire (version 4) at enrolment, 3, 6, 9, 12, 15 and 18 months
Secondary outcome measures
Drug adherence measured using the Modified Medication Adherence Report Scale (MMARS) and the Medication Possession Ratio (MRP) at 3, 6, 9, 12, 15 and 18 months
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Chinese women with histologically confirmed estrogen receptor-positive, stage I–III, primary invasive breast cancer
2. Treated with definitive surgery and/or chemotherapy and started on tamoxifen (20 mg daily) within the past month
Target number of participants
Participant exclusion criteria
1. Patients with other primary malignancies within the last 5 years
2. Patients who are pregnant or are planning to become pregnant, lactating
3. Treated with investigational drugs within the 4 weeks prior to enrolment
4. Not able to provide informed consent
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
The Chinese University of Hong Kong
Department of Clinical Oncology Prince of Wales Hospital, Shatin, New Territories
Chinese University of Hong Kong
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Planned publication in peer-reviewed journals at 6-12 months after the data collection was ended.
IPD sharing statement
The datasets generated during and/or analysed during the current study are not expected to be made available as the researchers planned to have the data for research and publication use only. They will keep the dataset in their computer with encryption.
Intention to publish date
Participant level data
Not expected to be available
Basic results (scientific)