Group interventions for patients with cancer and HIV disease: Part III. Moderating variables and mechanisms of action.

Growing evidence supports the value of group interventions for individuals who are at risk for or have developed cancer or HIV disease. However, information is more limited concerning how these services can be delivered in an optimal manner, and what processes contribute to their benefits. Parts I and II of this review examined the efficacy of different interventions for individuals at different phases of illness, ranging from primary prevention to late-stage disease, in both psychosocial and biological domains. The current paper examines some of the factors other than phase of illness that might influence group treatment effects (e.g., intervention parameters, participant characteristics), and explores mechanisms of action.