Symptom clusters: Revisiting the concept in nursing care for cancer patients

Studies on symptom clusters among cancer patients have been conducted intensively. However, the concept seems not to be well defined, hindering its utilization in clinical practice.The aim of this paper is to reconceptualize symptom cluster and discuss areas of future research.A cluster of symptoms should not be viewed as simply as a group of symptoms appearing together. It should be clinically relevant, and symptom members should be interactive or have a mutual etiology. A cluster is declared as stable if its "quality" or "nature" is remained instead of merely having the same number of symptoms. Importantly, each symptom cluster should have a sentinel symptom. The sentinel symptom could be the one that predicts the presence of the cluster or could be the one that significantly interacts with other symptoms. The search for symptom clusters, which are common among various patient groups, might be helpful in some aspects. However, to better understand them, symptom clusters should be examined in specific populations.The nature of the relationship between symptom members, clinical relevance, sentinel symptom, stability, and prevalence are important features of a symptom cluster. More explorations into these properties by future studies are suggested.