Introduction: Getting cancer is stressful for most patients and their relatives, and research has shown that psychosocial support is needed. Still, cancer care fails to appropriately address psychosocial problems associated with cancer. Research on this topic is often seen from the perspective of either the patient or the relative, even though it is suggested that psychosocial support is beneficial for the patient and the relative as a pair. Furthermore, research on the need for psychosocial support rarely involves patients with gynecological and lung cancer and their relatives, even though they often suffer from isolation and stigmatization. The aim of this review was therefore to summarize knowledge about psychosocial support with regard to individual needs, involvement of significant others, and providers of psychosocial support focusing on this specific population. Method: A narrative review procedure was chosen. This method is a specific kind of review, which summarizes, explains, and interprets evidence on a selected topic. The review process was structured according to typical scholarly articles with attention to the search and review process. Results: A total of 16 studies were included in the review. The studies were divided into two main categories: (1) studies focusing on needs for psychosocial support; and (2) studies focusing on interventions. The needs studies were analyzed, and three themes emerged: the needs of the patient and the significant other across the cancer trajectory; the needs of the significant other as a carer; and needs and ongoing and tailored support. The intervention studies were directed toward the patient and the relative, the patient, or the relative. Five interventions comprising various forms of support that were purely supportive and were carried out by healthcare professionals were identified. Conclusion: There were overlaps between the needs of the patient and the relative, but there were also distinctive characteristics of the needs in the two groups. The needs varied during the cancer trajectory, and we therefore recommend that support be offered continuously. It was also evident that the relatives should be involved in the patients’ care and that the involvement was beneficial for both the patient and the relative.