Purpose of review: Pain is probably the most feared symptom in cancer, and pain control has received considerable attention. Adequate pain management requires precise and thorough assessment including universally accepted definitions; an area with a great potential for improvement. There is still little consensus on how to categorize or classify cancer pain. The recent literature was reviewed in order to evaluate the development in cancer pain classification and assessment, respectively.
Recent findings: At present, only three standardized, systematically developed but not fully validated pain classification systems exist. However, their use in clinical practice is relatively limited, with one exception; the Edmonton Classification System for Cancer Pain, which is now subject to a large, international validation study. The findings from the cancer pain assessment literature reveal a plethora of instruments indicating that tool development is a continuous process, which does not follow systematic guidelines. The driving force is most often specific research interests in a limited number of issues related to cancer pain.
Summary: There is still no universally accepted tool for cancer pain assessment or general agreement on which domains to include in a classification system. In order to improve cancer pain management and research, we need to agree internationally on how to classify and assess cancer pain. Consensus can only be achieved through worldwide research collaborative work employing a systematic, stepwise process based on the existing body of knowledge, patient and expert opinions and clinical validation studies.