The control group received only usual care. They did not receive any intervention during the study period.

Nurse-led supportive care was given to primary caregivers of women with breast cancer. Nurse-led supportive care was applied to primary caregivers for eight weeks in the form of face-to-face clinic interviews. It took an average of 30 minutes to interview with primary caregivers at the clinic.

The ZBI is a measure of caregiving burden developed by Zarit et al. (1980). The Turkish version of this scale has been validated by Inci and Erdem (2018). It consists of 22 items, and responses are recorded on a five-point Likert scale. The level of caregiver burden can be ascertained based on the total scale scores, which range from 0 to 88. Higher scores indicate a higher level of caregiver burden.The Cronbach's α of the Turkish version of this scale was 0.91 in Inci and Erdem (2018) validation study

The scale was developed by Berg-Weber et al. (2000) in order to measure the level of caregivers of patients with chronic diseases to meet their basic needs and activities of living. The scale is made up of two subscales, namely, basic needs and activities of living, which try to measure the daily activity level of the caregivers. It consists of 44 items, and responses are recorded on a five-point Likert scale. Higher scores indicate a higher level of well-being. The Cronbach's α of the Turkish version of this scale was 0.86 in Demirtepe and Bozo (2009) validation study.