Smoking is an adverse prognostic factor for CML

Cancer, February 2017; advance online publication

medwireNews: Smoking increases the risk for disease progression and premature death in patients with chronic myeloid leukemia (CML), research indicates.

Among 1326 patients from the German CML Study IV for whom smoking status was available, 261 (20%) were current smokers at the start of the study. These patients were estimated to have an 8-year overall survival probability of 83%, compared with 87% for their peers who did not smoke.

In a univariate analysis, smokers had a nonsignificant higher risk for death than nonsmokers, with a hazard ratio of 1.38. But after accounting for other adverse prognostic factors, such as increasing age, comorbidities, spleen size, and peripheral blasts, smokers were estimated to have a significant 2.08-times higher risk for death than nonsmokers.

Michael Lauseker (Ludwig-Maximilians University, Munich, Germany) and colleagues therefore believe that “when determining the prognosis of a patient with CML, smoking should be considered to be an important prognostic factor.”

To support this recommendation, they report that CML patients who smoked also had a 2.11-times greater risk for progressing to accelerated phase or blast crisis than nonsmokers after accounting for the other prognostic factors.

The team speculates that a higher frequency of potentially malignant mutations may be one reason for the higher risk for disease progression in smokers with CML and recommends further study of patients’ mutation profiles as well as their smoking status.

Age was found to be an influential factor, with the negative impact of smoking on survival diminishing in older people.

For example, while a 16-year-old CML patient who smoked had a significant 8.47-fold increased risk for death compared with a nonsmoking CML patient of the same age, an 80-year-old smoker with CML was not at a significantly greater risk for death than an 80-year-old non-smoker.

“Therefore, the results of the current study suggest that patients with CML, especially those aged <60 years, should receive adequate encouragement and support to quit smoking,” the researchers recommend in Cancer.

They note that smoking status was only recorded at baseline and so the effects of quitting smoking could not be determined. “[I]t might be of further interest to learn whether patients who stop smoking early during the course of disease experience a good prognosis similar to that of nonsmokers,” Lauseker and co-workers conclude.

By Lucy Piper, Senior medwireNews reporter

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