OBJECTIVE : Numerous studies on cancer patients have shown that cancer pain still remains underestimated, poorly assessed, and under-treated. Pain relief should be considered as early as possible within personalized care and as an integral part of quality healthcare in many countries. Nevertheless, personalized care is still insufficiently taken into consideration, partly due to improper or incomplete assessment of cancer pain. The objective of this article is to propose a practical approach to this complex assessment, as the first step to improving patients' quality of life. METHODS : Critical reflection based on literature analysis and clinical practice. RESULTS : Assessment of cancer pain means evaluating the pain intensity over time, the dimensions of pain (sensory-discriminative, cognitive, emotional, and behavioral), the pathophysiological nature of pain (neuropathic, nociceptive, and nociplastic), the etiology, and the patient's perception (diffuse, localized, global). Cancer patients may have simple or multiple forms of pain (mixed, overlapped, combined, and associated). Furthermore, with the use of new specific therapies, the symptomatology of pain is also changing, and certain cancers are becoming chronic. Thus, cancer pain is an archetype of multimorphic pain, and its dynamic assessments (regular and repeated) require a multimodal and targeted approach in order to offer personalized pain management. Multimodal pain treatment must be adapted to the elements that disrupt cancer pain, to the patient's cancer and to the specific treatments. CONCLUSIONS : The dynamic assessments of pain demand the simplest, and the most complete possible procedure, to avoid feasibility problems or self-/hetero-assessment excesses that might lead to less precise and less reliable results. Multimodal and interdisciplinary approaches are being developed, making it possible to optimize cancer pain management.