Clinical Epidemiology and the Impact of Comorbidity on Treatment and Outcome

In the beginning of the twentieth century lung cancer was a very rare disease, but rates have increased so dramatically that lung cancer can be considered one of the major epidemics of the twentieth century. Currently, lung cancer is still number one cause of death among cancer deaths. Over fifty percent of all newly diagnosed lung cancer patients are aged over 65 years at the time of lung cancer diagnosis, and about 30% are aged over 70. Since lung cancer is a disease that mainly occurs in elderly and smoking is the most important risk factor, many patients have (smoking-related) comorbidity at the time of lung cancer diagnosis. This may complicate the management of lung cancer in elderly patients. Elderly receive standard treatment less often, although standard treatment has a positive effect on prognosis of lung cancer, even after adjustment for differences in age and comorbidity. However, complications of treatment among elderly patients are very common, despite a strict selection of the fittest elderly for standard treatment. In elderly, the impact of toxicities on quality-of-life may be just as important as the prolongation of life expectancy. A proper selection of patients fit enough for surgery, chemotherapy and/or radiotherapy is therefore important and there is an urgent need for predictive models for treatment tolerance that can be easily used in everyday clinical practice.