Condition category
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

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

Trial website

Contact information



Primary contact

Prof Carmen Wing Han Chan


Contact details

Room 732
Esther Lee Buidling
The Chinese University of Hong Kong
Hong Kong
Hong Kong
+852 (0)39436218

Additional identifiers

EudraCT number

Nil known number

Nil known

Protocol/serial number

Nil known

Study information

Scientific title

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


Study hypothesis

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

Ethics approval

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:, Approval #2016.554

Study design

Prospective cohort study

Primary study design


Secondary study design

Longitudinal study

Trial setting


Trial type

Quality of life

Patient information sheet


Breast cancer


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.

Intervention type



Drug names

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

Participant type


Age group




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

Hong Kong

Trial participating centre

The Chinese University of Hong Kong
Department of Clinical Oncology Prince of Wales Hospital, Shatin, New Territories
Hong Kong
Hong Kong

Sponsor information


The Chinese University of Hong Kong

Sponsor details

The Nethersole School of Nursing
Esther Lee Buidling
Hong Kong
Hong Kong
+852 (0)39438174

Sponsor type




Funder type


Funder name

Chinese University of Hong Kong

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

Local government


Hong Kong

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)

Publication list

Publication citations

Additional files

Editorial Notes

20/10/2020: The recruitment end date was changed from 31/07/2021 to 31/08/2020. 04/08/2020: The following changes were made to the trial record: 1. The recruitment end date was changed from 31/07/2020 to 31/07/2021. 2. The overall end date was changed from 31/08/2020 to 31/08/2021. 3. The intention to publish date was changed from 31/08/2021 to 31/08/2022. 4. The plain English summary was updated to reflect these changes. 28/05/2020: Due to current public health guidance, recruitment for this study has been paused. 07/04/2020: Internal review. 26/09/2019: Trial's existence confirmed by ethics committee.