e20658 Background: Chemotherapy regimens for the elderly with non-small-cell lung cancer (NSCLC) are still controversial, especially for patients over 80 years. We previously reported that biweekly combination therapy with gemcitabine and low-dose carboplatin was well tolerated and active in elderly patients aged ≥76 years with NSCLC (Lung Cancer 77, 2012). Here we present a subanalysis of more elder patients aged ≥80 years. Methods: We conducted a phase II trial comparing biweekly combination therapy with gemcitabine (1000mg/m2) plus carboplatin (AUC 3) and monotherapy with weekly gemcitabine (1000mg/m2) in chemotherapy-naïve NSCLC patients aged ≥76 years. We performed a retrospective subgroup analysis comparing patients aged < 80 and those ≥ 80 years. We focused on patients treated with combination therapy. The primary endpoint was overall response rate and secondary endpoints were safety and progression free survival (PFS). Results: Sixteen patients were aged < 80 years (median 77.5, range, 76-79 years) and 15 patients were aged ≥80 years (median 83, range 81-88 years). Overall response rates were 25% (95% CI: 7.3-52.4%) for patients aged <80 years and 20% (95% CI: 4.3-48.1%) for patients aged ≥80 years. The median PFS in patients aged <80 years was 3.5 months (95% CI: 3.2-5.6), compared with 3.6 months (95% CI: 2.8-5.0) in patients aged ≥80 years. Additionally, the prevalence of grade 3 or 4 hematologic and non-hematologic toxicity, the completion of four cycles chemotherapy, and the need for withdrawing treatment were not significantly different between the two groups. Conclusions: In elderly patients with NSCLC, even aged ≥80 years, combination therapy with biweekly gemcitabine and low-dose carboplatin may be an efficacious treatment with a favorable toxicity profile. Clinical trial information: NCT00881296.