Family members of cancer patients experience major changes in their daily lives due to their loved one's illness. The associated stress spreads across all aspects of their lives, physical, emotional, psychological and social, and due to risk of physical and mental illness posed, these family members are referred to as secondary patients. With advances in cancer medicine, family participation is required in various aspects of patient decision‒making, and families must address many challenges, not just nursing. After the patient's death, the family then becomes the bereaved family. The bereaved families of patients who died of cancer have characteristic burdens such as"regret"", unhelpful communication", and"anniversary reactions", and it is necessary to take appropriate measures while paying attention to the risk of physical and mental illness among the family members. In addition, it is important to have knowledge not only of physical and mental problems but also legal problems that arise, and to ask a specialist when necessary to support patients, families, and bereaved families.