Preexisting problems can contribute to the patient's pain, (i.e., migraine headaches, chronic back pain).

Concomitant illnesses, some reversible, occur in cancer patients, which can contribute to overall pain.

Most cancer patients are in the fifth or later decade of life. These individuals quite likely have some chronic bone or joint problems, respiratory, or gastrointestinal dysfunctions. Each can contribute to the pain which is then labeled "cancer" pain.