(HealthDay News) – Men with non-small-cell lung cancer (NSCLC) treated with crizotinib exhibit rapid suppression of total testosterone (T) levels compared with those who do not receive crizotinib treatment, according to research published online April 4 in Cancer.

Andrew J. Weickhardt, MBBS, DMedSci, of the University of Colorado Anschutz Medical Campus in Aurora, and colleagues conducted a studying measuring T levels in 38 men with metastatic NSCLC, of whom 19 received crizotinib and 19 did not.

The researchers found that low total T levels (<241ng/dL) were seen in 100% of crizotinib-treated men versus 32% of non-crizotinib-treated men. The mean total T levels were significantly lower in crizotinib-treated versus non-crizotinib-treated men (131ng/dL vs. 311ng/dL). Low T levels were seen in one of five patients who had anaplastic lymphoma kinase gene rearrangements and had not yet received crizotinib. Two patients who previously had normal T levels had a rapid decrease in T and in luteinizing and follicle-stimulating hormone levels within 14–21 days of treatment initiation.

“In summary, low T levels were documented in all of our male patients with metastatic NSCLC who received crizotinib treatment,” the authors write. “Changes appeared to be both rapid and reversible on commencement and cessation of dosing, respectively, confirming a direct causal relation with crizotinib.”

Several authors disclosed financial ties to Pfizer, which manufactures crizotinib. Both authors of the accompanying editorial disclosed financial ties to pharmaceutical companies, including Pfizer.

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