Population Level Survival of Patients with Chronic Myeloid Leukemia in Germany in the Early 21^st Century

Chronic myeloid leukemia (CML) is a rare but highly treatable form of leukemia. Recent advances in the treatment of CML have dramatically improved survival in clinical trials. Prior work using the Surveillance, Epidemiology, and End Results (SEER) database in the United States (US) suggest that survival on the population level has increased, but still lags behind that seen in clinical trials¹. In the past, evaluation of population level survival in other countries has been hampered by the lack of high quality data from a large enough population to evaluate trends in survival in this rare disease. Recently, a collaborative effort between the German Cancer Research Center and several German cancer registries has provided the chance to evaluate population level survival for rare cancers. Here, we examine survival for patients with CML in Germany in the early 21^st century, comparing it to survival in the US.

Data was extracted from the SEER13 database in the US and 13 epidemiologic cancer registries in Germany. Patients diagnosed with CML between 1997 and 2006 were included in the analysis. Data quality analysis showed an excessive level of cases diagnosed by death certificate only in older patients (age 70+) so analysis was restricted to patients age 15–69. Patients diagnosed by death certificate only were excluded from the analysis. Period analysis was used to provide the most up-to-date possible estimates of five year relative survival.

1848 cases of CML were identified in the German database and 2910 cases in the SEER database. More cases were seen in younger patients in the US, whereas each age group was roughly equal in size in Germany (see table). Five year relative survival was 68.7% overall in Germany and 72.7% in the US. Survival was higher in the US for all age groups except for age 15–39, but the difference was only significant for ages 50–59, where a difference of 10.2 percentage units was seen (see table). Survival decreased with age, ranging from 83.1% and 81.9%, respectively, in Germany and the US for patients age 15–39 to 54.2% and 54.5%, respectively, in patients age 65–69.

Estimated five year survival increased in the US compared to previous estimates of survival in the 2000–2004 period¹. Five year survival estimates were higher in the US than in Germany overall, but the difference was only significant for age 50–59. These results are the first detailing survival in CML on the population level in Germany and providing an international comparison. Survival did not equal that seen in clinical trials of tyrosine kinase inhibitors² for either country, but comparison with previous estimates in earlier time periods suggests that improvement in survival is ongoing. Greater concentration on treatment of CML in older patients may help improve survival for this population, for which survival lags.

No relevant conflicts of interest to declare.