(40) The Impact of Improved Treatments on Survival of US Leukemia Patients: 1990-2018

Publication Number: 371

Background: Survival for leukemia subtypes vary greatly due to availability of novel treatments, which are available for some but not all subtypes. Molecularly targeted therapies such as TKIs have been shown to be effective for treating Ph+ leukemias, and other precision oncology as well as immunotherapy regimens have been approved in leukemias at an increased rate over the past two decades.

Objectives: To evaluate population level mortality trends by CML, ALL, and CLL subtypes to assess how varying levels of targeted treatments penetrations may impact the mortality trends at the population level.

Methods: We used data from 13 US SEER cancer registries (1992-2017) among US adults. We identified cases of CML, ALL, and CLL using histology codes. Incidence rates were calculated after accounting for reporting delays. To calculate mortality rates, cause of death was ascertained from death certificates during 1992-2018. Finally, we present estimates of 5-year relative survival according to subtype and diagnosis year.

Results: For CML patients, mortality rates began to decline in 1998 at an average rate of 12% annually. Imatinib was approved by the FDA for treating CML and ALL indications in 2001, leading to a clear benefit on CML patients. CML incidence was stable during 1992-1995, decreased from 1995-2002 at 2.4% annually, and then increased gradually beginning in 2002 at 1.5% per year. Five-year CML survival increased dramatically over time, especially on average of 2.3 percentage points per year from 1996-2011. ALL incidence increased gradually 1992-2017. In contrast, mortality decreased slowly during 1992-2012 and then no longer was found to be declining during the study period. Five-year survival increased on average 1 percentage point for each subsequent year of diagnosis. CLL incidence fluctuated during 1992–2017. In contrast, mortality decreased during 1992-2011 and then declined at a faster rate by 3.6% per year starting from 2011. Five-year survival increased steadily during 1992-2016.

Conclusions: Our study demonstrates a fluctuation in rates of incidence and survival in all studied leukemia subtypes with a marked and significant reduction in CML mortality in the U.S. general population, which was primarily due to the introduction to the TKIs starting in 2001. Survival benefit from the TKIs and other novel therapies for treating various leukemia subtypes has been demonstrated in clinical trials. Our study highlights the impact of these therapies at the population level.