Background: An effect of comorbidity, or the coexistence of other diseases, on the stage of cancer at diagnosis and the appropriateness of therapy in older patients with cancer is hypothesized. The effect of comorbidity differs by cancer site and by type of comorbidity. Such variation could be due to the use of different populations or methods, or the natural history of the tumor being studied.
Methods: The National Institute on Aging (NIA) and the National Cancer Institute (NCI) have initiated a study using cancer patient populations in the NCI's SEER (Surveillance, Epidemiology and End Results) program. Five geographic locations participated in the NIA/NCI pilot study of comorbidity associated with seven cancer sites. Approximately 250 patients with each type of cancer, stratified by age (either 65-74 years of age or 75 years and older) had hospital records abstracted for comorbidity using a form derived from previously reported methods.
Results: After analyzing preliminary results for 1712 patients, it was ascertained that more and different chronic disease categories would be necessary, that it was not feasible to collect data on ability to perform certain physical functions from the medical records, and that the collection of data on current medications was possible. With these limitations, relationships of comorbid conditions with stage of cancer were analyzed.
Conclusion: With the success of the pilot study, the full study is underway. In addition to the planned abstracting of approximately 7800 records, interviews assessing the behavior of illness in a sample of 1000 cancer patients will provide valuable information on the influence of comorbidity and age on stage at initial diagnosis and the treatment of older persons afflicted with cancer.