Many studies have added quality of life measurements into clinical trials of cancer therapies. Generally, these instruments measure self-reported functional status, physical, emotional and spiritual well-being, and social functioning. The quality of life in these trials can be affected by the disease process and the treatment protocols. Patients' pain levels can also have a significant impact on these measurements, yet few clinical trials assess this as part of the quality of life measurements. Wang and colleagues studied the relationship between pain severity and patients' self-reported quality of life.

The 216 patients enrolled in the study were consecutive patients at two cancer centers who had an established diagnosis of metastatic cancer. The majority of patients enrolled in the study had cancer-related pain and were receiving analgesics. Patients completed the Brief Pain Inventory and the Medical Outcomes Study 36-Item Short-Form Health Survey. The physicians involved in the study documented the characteristics of patients' cancers, performance status, pain assessment and current pain therapy.

The severity of pain had a direct correlation with patients' health-related functioning. This was true even when disease severity was factored into the study. Patients who had no pain or only mild pain had significantly better scores on the health and well-being measurements than patients with moderate or severe pain.

The authors conclude that pain is an important variable to consider when evaluating patients' quality of life. Patients with no pain or only mild pain functioned at similar levels. Providing adequate pain control can have a significant effect on the functional status of cancer patients.