The role of the psycho-oncologist in providing psychological support to the families of cancer patients is based on the principle that cancer is not only a physical illness for the affected person, but is also a critical event that affects the family's emotional, relational, and functional system. The family faces a series of psychological pressures at all stages of the disease, from diagnosis to treatment, rehabilitation, the possibility of relapse, palliative care, and even bereavement. In this situation, the psycho-oncologist evaluates the emotional reactions of family members from a biological, psychological, social, and family perspective and tries to balance the patient's needs and the family's psychological capacity. A cancer diagnosis can cause feelings of shock, disbelief, fear, anger, sadness, helplessness, and worry about the future in family members, and the severity of these reactions depends on the type of cancer, prognosis, stage of the disease, economic status, psychological history, and the level of social support. From a theoretical perspective, the family can be considered as an interconnected system in which the change in the status of one of its members also changes the emotional and communication patterns of the other members. Therefore, psycho-oncological intervention is not limited to reducing the anxiety of an individual, but also focuses on regulating family interactions and increasing the adaptive capacity of the whole family system. In the first step, the psycho-oncologist identifies the extent of psychological distress in family members and examines factors such as anxiety, depression, sleep disturbances, feelings of guilt, fear of loss, caring burnout, and communication problems. One of his most important tasks is to create a safe space to express emotions that family members sometimes suppress due to fear of upsetting the patient or maintaining a calm family appearance. Psychological education is also an important part of this process, as many families do not have enough information about normal psychological responses to cancer and may consider symptoms of anxiety or depression as a sign of personality weakness. By explaining the nature of psychological reactions, the psycho-oncologist helps the family better understand their emotional experience and not feel ashamed or guilty about it. In families where a member plays the role of the primary caregiver, the risk of physical and psychological exhaustion increases, and professional support should include the family caregiver in addition to the patient. Training in caregiving, emotion regulation, problem-solving, effective communication, and self-care can increase the caregiver's capacity to continue to support the patient. Research evidence in the field of psycho-oncology suggests that family psychological interventions can play a role in reducing distress, anxiety, and some communication problems and in improving family adjustment to illness, although the size of the effect and response rate to the intervention are not the same in different studies. Interventions based on cognitive behavioral therapy can help identify catastrophic thoughts, ongoing worries, and dysfunctional beliefs about the future. Approaches based on acceptance and commitment can also help family members balance experiencing difficult emotions and continuing their daily lives. In some families, meaning and spirituality also play an important role in coping with the disease, and the psycho-oncologist can bring these dimensions into the process of psychological support without imposing any particular beliefs on the family. Another important application of the intervention is to improve communication between the patient and family members, as the fear of cancer sometimes causes the family to avoid talking about the disease, prognosis, or future concerns. By teaching empathetic communication, active listening, and expressing needs, the psycho-oncologist can create conditions where family members can express their feelings and expectations without blame or pressure. In treatment decisions, the family may also find a conflict between supporting the patient's independence and wanting to protect the patient. In such a situation, the psycho-oncologist can help clarify the role of family members and respect the patient's preferences. Psychological support is also particularly important during the course of chemotherapy, as the complications of treatment can increase the pressure of care and concern for the family. During the course of radiation therapy or long-term treatments, the burnout caused by continued care may gradually become apparent and require ongoing evaluation. In the post-treatment phase, the family may assume that all mental health problems are over by the end of treatment, while fear of relapse, anxiety about tests, and changing family roles can continue. At this stage, the psycho-oncologist helps the family balance health-centered care with a gradual return to normal life. In advanced illness or palliative care, the focus of the intervention can move from controlling anxiety symptoms to emotional support, effective communication, meaning, decision-making, and psychological preparation for future changes. The family's exposure to the possibility of death is one of the most complex psychological situations and requires a sensitive, gradual intervention that is tailored to the family's culture and beliefs. The psycho-oncologist can also identify symptoms of premature grief, severe depression, persistent anxiety, and caregiver burnout, and refer the family for more specialized services if needed. In terms of clinical application, family interventions can be designed individually, as a couple, as a family, or as a group, and the choice of intervention should be based on the family structure, stage of illness, distress severity, and support resources. The use of art, narrative therapy, and creative activities can also be a complementary way to express emotions that are difficult for the family to express directly in some situations. However, art therapy should not replace psychological assessment and specialized treatment of clinical disorders, but can be used within the framework of a comprehensive program. One of the main challenges is the difference in the psychological needs of family members; one member may need more information, another may need emotional support, and another person to care skills training. Another limitation is the unequal access of families to specialized psycho-oncology services, the cost of treatment, the lack of specialists, geographical distance, and sometimes negative attitudes towards receiving psychological services. The economic strain caused by treatment costs can also exacerbate family distress and needs not to be ignored in psychological evaluation. Cultural differences also affect the way emotions are expressed, family decision-making, the role of the caregiver, and the way of coping with death, and the intervention should be adapted to the family's cultural context. Another limitation is the possibility of over-focusing on the family and ignoring the patient's independence and preferences, so family support should be provided alongside respect for the rights and choices of the person with cancer.