As discussed in Chapter 3, the absence of a commonly understood vocabulary to describe psychosocial health services and interventions hinders the identification, interpretation, analysis, and application of evidence of effective delivery of those services. Developing a language that can be used across professions and disciplines is critical to the production of better evidence to support the delivery of effective psychosocial health services, which are themselves multidisciplinary and multiprofessional.

Although evidence described in Chapters 3, 4, and 5 supports the health care benefits of providing psychosocial health services and points to ways of doing so effectively, there are still many unanswered questions. Key questions remain about how to address certain psychosocial health problems most effectively, as well as how to deliver services most efficiently to the various individuals who need them.

As is the case in biomedical care, providing effective psychosocial services to all who need them is hindered in part by limitations of the knowledge base. For the past three decades, the National Cancer Institute (NCI) and other private organizations that fund cancer research have supported a wide range of psychosocial research studies involving cancer patients and their families. However, the challenge with cancer is that it is not a single disease (prostate cancer, for example, is different from lung cancer in its impact), and even for a particular cancer site, individuals’ specific psychosocial health care needs may vary (e.g., in early-stage versus advanced disease). Given that there are more than 100 specific cancer types, it is therefore difficult to generalize about the benefits of particular psychosocial interventions, as their efficacy may vary based on the cancer site or phase of disease. Increasingly, research studies have focused on homogeneous samples of patients, making interpretation of outcomes more salient. For these reasons, psychosocial research with cancer patients is more challenging than that focused on more homogeneous diseases, such as asthma, diabetes, or heart disease.