Pemetrexed long-term maintenance therapy for advanced severe lung cancer with long-term progression-free survival: a case report.

It is relatively rare to achieve a median progression-free survival (PFS) of 40 months with pemetrexed monotherapy maintenance, especially in patients with advanced and severe lung cancer. Here, we reported a case of advanced severe lung adenocarcinoma treated with pemetrexed monotherapy maintenance achieving long survival with a median PFS of 46 months. A 52-year-old female diagnosed with stage IV lung adenocarcinoma was tested for no targeted drug benefit in the driver gene. The patient was financially disadvantaged and could not afford and refused immune checkpoint inhibitor drugs but was in the favor of platinum-based double-drug chemotherapy. After six cycles of effective administration of cisplatin in combination with pemetrexed, pemetrexed monotherapy was given for long-term maintenance treatment to date, with a median PFS of 46 months, with a treatment effect close to complete response and tolerable side effects.