In recent years, psychological interventions in the care of cancer patients have gone beyond a purely supportive position and have been considered as one of the important components of managing the psychological and behavioral consequences of the disease in the framework of comprehensive care and psychosocial life. Cancer diagnosis can be made by creating a sense of threat, uncertainty, worry about the future, fear of recurrence, disruption in family roles, body image changes, pain, fatigue, and disorder Sleep can be associated with a high level of distress or psychological distress. This condition is not just a mental experience, but chronic stress can be linked to certain physiological processes through interaction with the autonomic nervous system and the pituitary-adrenal axis. From this perspective, psycho-oncology tries to reduce psychological suffering and also address the relationship between mental health, health-related behaviors, inflammation, and immune system function.
Distress in patients with cancer is a broad concept and can include a range of normal concerns about the disease to anxiety and clinical depression. Its severity is not constant throughout the course of the disease and may increase at the time of diagnosis, initiation of treatment, waiting for results, the course of chemotherapy, the end of treatment, or when there is concern about recurrence. Therefore, the first step in psychological intervention is to accurately identify the level of distress and its causative factors. Systematic screening can identify patients who require specialized support and allow interventions to be tailored to the severity and type of need.
From a psychoneuroimmunological perspective, the relationship between distress and the immune system is explained through a network of neuronal, endocrine and inflammatory pathways. Continuous experience of stress can increase the activity of the sympathetic nervous system and alter the pattern of HPA-axis activity. As a result, there are changes in the secretion of substances such as cortisol and catecholamines, which can be associated with the regulation of immune and inflammatory responses. However, this association is very complex and it cannot be expected that a psychological intervention will alter a specific biomarker in all patients in the same way.
In this context, cognitive-behavioral therapy is one of the most well-known approaches used in psycho-oncology. By focusing on dysfunctional thoughts, catastrophic concerns, avoidance, maladaptive behaviors, and coping skills, it can help reduce anxiety and depression. Reducing threat-oriented thoughts and increasing feelings of control may help reduce the ongoing activation of the stress response. However, the main importance of these interventions in cancer patients is to reduce suffering and promote adaptation, and any changes in safety indicators should be scientifically investigated as a possible and secondary outcome.
Mindfulness-based interventions have also been considered in this area. Mindfulness can help some patients manage anxiety, stress, and sleep disturbances by teaching them to pay attention to the present experience and reduce automatic reactivity to thoughts and emotions. Theoretically, reducing stress reactivity may modulate the repetitive activity of the sympathetic nervous system and the HPA axis. As a result, the possibility of changes in some inflammatory and immune processes has been raised, but the extent and persistence of such effects depends on the type of intervention, its duration, patient characteristics, and the method of measuring biomarkers.
Acceptance and commitment therapy can also be applied to cancer patients. This approach attempts to move the patient out of constant struggle with unpleasant thoughts and feelings and toward accepting the inner experience and moving toward personal values. In cancer, many factors are truly out of the patient's control, so increasing psychological flexibility can help reduce avoidance and rumination and increase participation in meaningful activities. Such changes may indirectly affect behavioral patterns, sleep, physical activity, and social interactions, thereby being linked to general health.
Meaning-based interventions are also important, as cancer can raise profound questions about meaning, identity, future, and life values. Helping the patient reconstruct meaning and find achievable goals can reduce feelings of helplessness. In a psychosocial context, a decrease in a sense of threat and an increased sense of psychological cohesion may be associated with a reduced stress burden. However, definitive claims about the direct effect of semantic therapy on tumor growth or immune response should be avoided, as the available evidence further supports psychological effects and quality of life.
Another important area is training in emotion regulation skills. Patients may experience fear, anger, sadness, guilt, or hopelessness, and the inability to identify and manage these emotions can exacerbate distress. Emotion recognition, acceptance, cognitive reassessment, problem-solving, and emotion tolerance training can increase a patient's coping capacity. Proper emotion regulation does not mean eliminating unpleasant emotions, but rather developing the ability to experience and manage them without getting caught up in a cycle of avoidance, repression, or rumination.
Sleep is also an important goal of psychological interventions. Insomnia and poor quality sleep are common in cancer patients and can exacerbate anxiety, fatigue, and cognitive problems. Sleep disturbances, on the other hand, are associated with changes in autonomic nervous system activity and certain inflammatory pathways. Cognitive behavioral therapy for insomnia, sleep hygiene education, relaxation techniques, and sleep schedule adjustment can help improve sleep quality. Improving sleep may indirectly create more favorable conditions for emotional regulation and physiological functioning.
Physical activity and health-related behaviors are also important in this model. Reducing distress may help increase patient participation in daily activities, better adhere to treatment recommendations, and maintain healthy behaviors. Appropriate physical activity is also associated with mood status, sleep quality, physical performance, and certain inflammatory markers. However, an activity plan should be tailored to the patient's medical condition and should never be recommended to the patient without coordination with the treatment team.
In the area of biomarkers, research has looked at markers such as C-reactive protein, interleukins, tumor necrosis factor, and other inflammatory mediators. Some studies have also investigated changes in the function of NK cells, lymphocytes, and other immune markers. The aim of these studies is to determine whether stress reduction and improvement in psychological status are associated with measurable changes in the immune system. The results are not the same in all studies, and differences in research design, type of cancer, stage of disease, type of treatment, and method of measurement may explain part of this heterogeneity.
One important problem in this area is the difference between 'biomarker change' and 'clinical outcome improvement'. Even if a psychological intervention alters an inflammatory marker, this alone does not prove that the cancer trend has changed. Clinical outcomes such as overall survival, progression-free survival, disease recurrence, and response to treatment are influenced by a complex set of factors. Therefore, psychoneuroimmunology research must distinguish between biomarkers, psychological outcomes, and actual disease outcomes.
From a clinical perspective, one of the important applications of this approach is the development of stepped care. In this model, the severity of distress and the type of patient need are initially assessed and then used according to the level of need, from psychological and self-care training to more specialized interventions. Patients with mild distress may benefit from education, social support, and self-help resources, while patients with more severe anxiety or depression may require specialized psychotherapy or psychiatric referrals. Such a pattern makes specialized resources more targeted to patients with greater need.
In the meantime, the psycho-oncologist can play an important role in the link between medical and psychological care. In addition to distress, the initial assessment should include anxiety, depression, sleep, pain, fatigue, emotion regulation, social support, concern about relapse, and economic and family factors. The intervention should then be tailored to the stage of the disease and the conditions of treatment. The patient may need more shock and uncertainty management during the diagnosis phase, coping and symptom control skills during treatment, and in the post-treatment period to reconstruct identity and manage the fear of relapse.
One of the major challenges is the timing of the intervention. Illness and cancer treatment may reduce the patient's energy and cognitive capacity, and long psychotherapy sessions may not be tolerable for all patients. Therefore, short-term, flexible, and feasible interventions in a cancer treatment setting can be of great importance. Also, the use of telephone and digital interventions can increase the accessibility of patients who are unable to attend regularly due to geographical distance, physical weakness, or a tight treatment schedule.
Another challenge is the control of intervening agents in biological research. Anti-cancer drugs, corticosteroids, infection, pain, nutrition, sleep, physical activity, and disease stage can all alter immune and inflammatory markers. Therefore, if a study only measures an inflammatory marker before and after a psychological intervention, it cannot be reliably attributed to the intervention. Future studies should use the appropriate control group, adequate samples, repeated measurements, and longer follow-up.
On the other hand, the heterogeneity of patients' responses suggests that a single intervention is likely not to have the same effect for all people. Characteristics such as type of cancer, stage of disease, age, physical condition, distress intensity, coping style, emotion regulation, and level of social support can influence response to the intervention. Therefore, the move towards psychological profiling and personalised interventions could be one of the future pathways of psycho-oncology. In this model, the goal is not just to reduce a Distress score, but to identify the main mechanisms that cause suffering in each patient and to choose an intervention tailored to the same mechanisms.
Ultimately, the relationship between psychological interventions and immune regulation should be understood in the form of a complex and multi-level network. Reducing distress, improving emotion regulation, modifying sleep, increasing adaptive activity, and strengthening social support can influence stress-related behavioral and physiological pathways and lead to some changes in inflammatory or immune markers; however, these changes should not be interpreted as evidence of a direct effect of psychotherapy on tumor growth. The main value of these interventions at present is in reducing psychological suffering, improving quality of life, increasing adaptability, and supporting patient participation in the treatment process. From a psycho-oncology perspective, attention to the immune system and inflammation brings the area closer to cancer biology, but the line between established evidence and the hypotheses under investigation must still be maintained.
The future of research in this area can move towards more accurate models by integrating psychological assessments, inflammatory and immune markers, autonomic neurological data, and clinical indicators. Longitudinal studies can determine under what conditions distress reduction is associated with biological changes and whether these changes are associated with significant clinical outcomes. Also, the use of wearable technologies to monitor sleep, physical activity, and some autonomic indicators can provide valuable information along with specialized psycho-oncological assessments. The desired approach is not to consider psychological and biological paths as two separate paths, but rather to consider the cancer patient as an integrated biopsychosocial system, a system in which psychological suffering, body care, symptom management, social support, and anti-cancer treatment are combined and their common goal is to increase the quality of life and adapt the patient to the complex course of the disease and treatment.