The prevalence of pain among cancer patients varies depending on which studies you reference, but it's often reported that up to 90% of cancer patients experience pain. Particularly concerning is that the severity of pain is typically high, especially in the later stages of cancer. When you consider that around 50% of cancer patients do not receive adequate pain management, it's clear that current approaches need re-evaluation. 

The World Health Organization (WHO) analgesic ladder has played a significant role in improving cancer pain control. It's a simple concept, easy to understand and apply, and has been widely adopted. However, despite its benefits, it still falls short in many cases. More recently, experts in pain medicine and palliative care have started questioning whether the WHO ladder is still the best approach.