First-line chemotherapy in very elderly patients with metastatic pancreatic cancer: Gemcitabine monotherapy vs combination chemotherapy

BACKGROUND: Combination chemotherapy (gemcitabine plus nab-paclitaxel and FOLFIRINOX) is widely used as the standard first-line treatment for pancreatic cancer. Considering the severe toxicities of combination chemotherapy, gemcitabine monotherapy (G mono) could be used as a first-line treatment in very elderly patients or those with a low Eastern Cooperative Oncology Group status. However, reports on the efficacy of G mono in patients older than 75 years are limited. AIM: To evaluate the efficacy of G mono and combination chemotherapy by comparing their clinical outcomes in very elderly patients with pancreatic cancer. METHODS: We retrospectively analyzed 104 older patients with pancreatic cancer who underwent chemotherapy with G mono (n = 45) or combination therapy (n = 59) as a first-line treatment between 2011 and 2019. All patients were histologically diagnosed with ductal adenocarcinoma. Primary outcomes were progression-free survival and overall survival. We also analyzed subgroups according to age [65-74 years (elderly) and ≥ 75 years (very elderly)]. Propensity score matching was performed to compare the outcomes between the two chemotherapy groups. RESULTS: The baseline characteristics were significantly different between the two chemotherapy groups, especially regarding age, ratio of multiple metastases, tumor burden, and Eastern Cooperative Oncology Group performance status. After propensity score matching, the baseline characteristics were not significantly different between the chemotherapy groups in elderly and very elderly patients. In the elderly patients, the median progression-free survival (62 d vs 206 d, P = 0.000) and overall survival (102 d vs 302 d, P = 0.000) were longer in the combination chemotherapy group. However, in the very elderly patients, the median progression-free survival (147 d and 174 d, respectively, P = 0.796) and overall survival (227 d and 211 d, respectively, P = 0.739) were comparable between the G mono and combination chemotherapy groups. Adverse events occurred more frequently in the combination chemotherapy group than in the G mono group, especially thromboembolism (G mono vs nab-paclitaxel vs FOLFIRINOX; 8.9% vs 5.9% vs 28%, P = 0.041), neutropenia (40.0% vs 76.5% vs 84.0%, P = 0.000), and neuropathy (0% vs 61.8% vs 28.0%, P = 0.006). CONCLUSION: In elderly patients, combination therapy is more effective than G mono. However, G mono is superior for the management of metastatic pancreatic cancer in very elderly patients.