Cancer survival as a function of age at diagnosis: a study of the Surveillance, Epidemiology and End Results database

Abstract

Background: Recent research suggested that cancer survival has improved in recent cohorts. Improvement in cancer survival is considered a valid indicator of the quality of care introduced to the patients. The aim of this study is to investigate the changes in the survival profile over age for patients with the most incident cancers.

Methods: Survival data of 3.94 million patients diagnosed with 23 primary-site cancers within the periods of 1979-1983, 1989-1993, and 1999-2003 were adopted from the Surveillance, Epidemiology and End Results database. Gender and cause-specific survival probabilities were estimated at one, three, and five years after diagnosis using the Kaplan-Meier survival estimate. Survival was presented for each of the studied cancers, cohorts, and sexes in the form of line graphs as a function of age at diagnosis. Error bars demonstrated the probability of error at 95% confidence level.

Results: The graphs demonstrated that cancer survival was improved over the successive cohorts for most cancers, with several exceptions such as brain and lung cancers. The relation between survival and the age at diagnosis was generally described in the form of a gradual decline phase and a rapid fall-off phase at 70-80 years of age, with few exceptions as in leukemia and Hodgkin lymphoma. Patients who survived for three years were more likely to live for five years after diagnosis, but this prediction could not be extrapolated to the one-year survivors.

Conclusion: Further studies on tumor-specific characteristics and treatment modalities of these patients are suggested for clarification of the possible causes of variations in patient's survival profile over age.