Risk of Secondary Cancers With CML Linked to Disease, Not Treatment
Secondary cancers occurred in 5.6% of the 9,200 adult patients with CML included in this study.
Patients with chronic myeloid leukemia (CML) have a 30% higher risk of developing a secondary cancer compared with the general population, and the risk is highest within the first year of diagnosis, according to an observational study published in PeerJ.1
As the long-term survival of patients with CML has increased, it is important to understand the long-term effects of tyrosine kinase inhibitor (TKI) treatment. The purpose of this study was to determine the risk of secondary cancers among patients with CML treated with TKIs.
The study included data from 9,200 adult patients with CML diagnosed and treated between 2002 and 2014 from the surveillance epidemiology and end results (SEER) database. Patients were followed for a mean of 4.2 years.
Secondary cancers occurred in 5.6% of patients, resulting in a standardized incident ratio (SIR) of 1.3 (95% CI, 1.2-1.4; P < .001), an excess risk of 30 cancers per 10,000 person-years, and an absolute excess risk (AER) of 1.3% per year compared with an age-, sex-, and race-matched general population. When stratified by sex, however, the elevated risk of secondary cancers was associated with men (SIR, 1.4; 95% CI, 1.3-1.7; P < .001), but not women.
Secondary cancers were most likely to develop between 2 to 12 months after CML diagnosis, but remained elevated for up to 5 years.
The most common secondary cancers were of the gastrointestinal tract (18%), prostate (18%), or lung (15%), or hematologic (15%, excluding acute myeloid leukemia and acute lymphoblastic leukemia). The greatest risk, however, was associated with cancers of the gingiva (SIR, 3.7; 95% CI, 1.2-8.7; P = .002), chronic lymphocytic leukemia (SIR, 3.4; 95 %CI, 2-5.5; P < .001), and the small intestine (SIR, 3.1; 95% CI, 1.2-7; P = .004).
These findings suggest that patients with CML, particularly men, are at an increased risk of developing secondary cancers. According to the authors, “the cause of elevated risk is not clear,” and, “the diagnosis of secondary cancers in the early period after CML diagnosis suggest the linkage to CML itself rather than TKIs.”
Kumar V, Garg M, Chaudhary N, Chandra AB. An observational study on risk of secondary cancers in chronic myeloid leukemia patients in the TKI era in the United States. PeerJ. 2018;6:e4342. doi: 10.7717/peerj.4342