Participants in the control group received standard treatment from oncologists and nurses at Hanoi Medical University Hospital.

In addition to standard care provided by oncologists and nurses at Hanoi Medical University Hospital as described above, participants assigned to the intervention group received the psychoeducational intervention delivered by the nurse researcher.

The total program, consisting of three intervention sessions, was given over a period of 3 weeks. The one face-to-face session of an-hour's duration was provided within a week of the chemotherapy cycle following recruitment. Two booster sessions of 20-30 minutes were then conducted by phone at one-week intervals after the first intervention session.

The three-single item Numeric Analogue Scales (fatigue, pain and sleep disturbance) were used at baseline and 4 weeks of the intervention to assess the change of symptom severity at cluster levels. The scales consists of a number of symptoms rated on the 11-point scales, with 0 referring to "not present" and 10 referring to "as bad as you can imagine". The symptom cluster severity was evaluated by averaging symptom summary scores, with a summary higher score indicating greater symptom cluster severity.

The Brief Fatigue Inventory (BFI) was used to assess the change of fatigue from baseline to 4 weeks of the intervention. The BFI consists of nine items assessing severity of fatigue in the past 24 hours (4 items) and its impacts on patients' different aspects of life, such as daily activity, emotional well-being, walking ability, work, and social interactions (5 items) on a 11-point scale. A summary higher score indicating greater fatigue severity and interference.

The Brief Pain Inventory was used to assess the change of pain from baseline to 4 weeks of the intervention. The Brief Pain Inventory - Short Form (BPI) encompasses a 4-item pain severity subscale and a 7-item pain interference with daily activities subscale. Each item was rated on 11-point numerical rating scales. A summary higher score indicating greater pain severity and interference.

The Pittsburgh Sleep Quality Index (PSQI) was used to assess patients' sleep quality and pattern at baseline and 4 weeks of the intervention. The scale consists of 19 self-reported items categorised in 7 domains, including sleep quality, duration, sleep effectiveness, sleep disturbances, sleep medication, and daytime dysfunction over the last month. Possible scores range from 0 to 21 with a higher score indicating greater sleep disturbance

Outcome measures included the Karnofsky Performance Scale at baseline and 4 weeks of the intervention. The scale ranges from 10 (moribund, fatal process progressing rapidly) to 100 (normal, no complaints, no evidence of disease).