Risk factors for predicting severe neutropenia induced by pemetrexed plus carboplatin therapy in patients with advanced non-small cell lung cancer

Pemetrexed plus carboplatin therapy is widely administered to patients with non-squamous non-small cell lung cancer. Although severe neutropenia is often observed during this combination therapy, its predictive factors are unknown. Therefore, we investigated the predictive factors for severe neutropenia in 77 patients treated with this combination therapy at the Department of Respiratory Medicine, Kyushu University Hospital, between September 2009 and September 2013. All data were retrospectively collected from the electronic medical record system, and univariate and multivariate logistic regression analyses were performed to identify risk factors for grade 3 or 4 neutropenia. Among the 77 patients, 34 (44%) developed grade 3 or 4 neutropenia. Multivariate analysis revealed that lower baseline hemoglobin values (odds ratio [OR], 1.97 per 1 g/dL decrease; 95% confidence interval [CI], 1.39-2.99, p<0.01) and lower baseline neutrophil counts (OR, 1.71 per 1000/mm³ decrease; 95% CI, 1.14-2.71, p=0.01) were significantly associated with grade 3 or 4 neutropenia. During 4 courses of pemetrexed plus carboplatin therapy, the incidence of grade 3 or 4 neutropenia in patients with baseline hemoglobin values of <11.6 g/dL was significantly higher than that in patients with values of ≥11.6 g/dL [84% (16/19) vs. 31% (18/58), p<0.001]. In conclusion, patients with lower baseline neutrophil counts or lower baseline hemoglobin values, especially those with baseline hemoglobin values of <11.6 g/dL, should be monitored more carefully during pemetrexed plus carboplatin therapy.