Korean Quality of Life in Stomach Cancer Patients Study (KOQUSS) Group

The KOrean QUality of life in Stomach cancer patients Study group consists of surgeons, medical oncologists, a clinical epidemiologist, and a psychometrician from 27 institutions in the Republic of Korea. Our purpose is to evaluate quality of life of patients who underwent gastrectomy for gastric cancer and to improve their postoperative quality of life. Since conventional quality of life questionnaires, such as EORTC QLQ or FACT, had several limitations, we have developed a quality of life questionnaire (KOQUSS-40) throughout three pilot studies and a validation study. Recently, we reported the final version of KOQUSS-40 and it is used in several clinical trials.
We will try to objectively evaluate the quality of life of gastric cancer patients and continue to conduct high-level clinical trials using the KOQUSS-40. Ultimately, we hope to improve the quality of life of gastric cancer patients.

Development of KOQUSS-40

Since conventional quality of life questionnaires, such as EORTC-QLQ or FACT, had several limitations, we planned to develop a symptom-focused quality of life questionnaire (KOQUSS-40) for Korean patients with gastric cancer. According to the principle of questionnaire development, two pilot studies were performed from September 2017 to August 2018, and a preliminary version with 40 items was developed. Then, a validation study was performed to evaluate its validity and reliability from January to March 2019, and the study revealed sufficient validity and reliability of KOQUSS-40. The final Korean and English version of KOQUSS-40 was published in Cancer Research and Treatment in July 2021.

Application of KOQUSS-40

In the present, the KOQUSS-40 is being used in several multicenter prospective clinical trials and a prospective observational study in Korea. Recently, it was translated into Italian and being used to evaluate quality of life in the Italian clinical trial. Moreover, it is going to be translated into Chinese soon and can be applied to Chinese patients with gastric cancer.

Current activity and perspective

The first symposium was held in January 2016 and a total of 10 symposiums have been held until now. In these symposiums, we studied questionnaire development methodology and research trends for quality of life in various diseases, and shared our useful tips to resolve patient symptoms. In addition, we have regular research meeting for a multicenter clinical trial. We hope that the KOQUSS-40 spreads worldwide and contributes to objective evaluation of patients’ quality of life. Finally, we hope to improve our patients’ quality of life.


The KOQUSS-40 is a questionnaire assessing quality of life of gastric cancer patients developed by the KOrean QUality of life Stomach cancer patients Study (KOQUSS) group. It consists of 40 items within 11 domains, including general quality of life, indigestion, dysphagia, reflux, dumping syndrome, bowel habit change, constipation, psychological factors, worry about cancer, scar problems, and financial problems. All items of the KOQUSS-40 are rated using a four-point Likert scale and each domain and total score can be calculated according to a set formula. Since the KOQUSS-40 focuses on postgastrectomy symptoms, it can objectively and effectively evaluate quality of life of gastric cancer patients. The KOQUSS-40 is used in several clinical studies in Korea, and will contribute to high-quality clinical research by enabling objective assessment of quality of life.