S-1, an oral fluoropyrimidine derivative, with or without platinum-based chemotherapy may be an effective long-term adjuvant therapy option among patients with completely resected non-small cell lung cancer (NSCLC), according to a study published in Lung Cancer.1

The standard of care for stage II or stage III NSCLC postoperatively is cisplatin-based chemotherapy, but analyses of previous studies demonstrated only marginal benefits in survival and severe toxicities. Evidence suggests that S-1 monotherapy may be safe and effective for patients with NSCLC, but no comparative studies had been performed against cisplatin-based chemotherapy prior to the current study. 

For this phase 2 study, researchers randomly assigned 141 patients with stage II or stage IIIA NSCLC to receive oral S-1 80 mg/m2or S-1 80 mg/m2plus cisplatin 60 mg/m2for 1 year. Eligible patients had undergone complete resection, were not previously treated with chemotherapy or radiotherapy, and had adequate bone marrow and organ function. Patient characteristics were well balanced between the 2 arms, according to the researchers. 

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Results showed that the 2-year disease-free survival (DFS) rate was 52% (95% CI, 0.40-0.63) in the S-1 monotherapy group versus 61% (95% CI, 0.48-0.70) in the S-1 plus cisplatin group; both arms met the primary end point goal of a 2-year DFS rate greater than 40%. 

No significant differences were observed between the 2 study arms for DFS (P= .1695) or overall survival (P= .8684).

The most commonly reported grade 3 to grade 4 adverse events (AEs) included appetite loss (S-1 vs S-1 plus cisplatin; 4.3% vs 11.6%, respectively), decreased neutrophil count (5.7% vs 10.1%), and anemia (0% vs 5.8%). There was no significant difference between the rates of treatment completion, with 45.7% and 43.5% in the S-1 only and S-1 combination arms, respectively. 

The authors concluded that “long-term adjuvant chemotherapy with S-1 was a feasible and promising treatment for patients with completely resected NSCLC, regardless of whether cisplatin was added. We recommend that S-1 monotherapy should be investigated further owing to its low toxicity and practical convenience.”


  1. Okamoto T, Yano T, Shimokawa M, et al. A phase II randomized trial of adjuvant chemotherapy with S-1 versus S-1 plus cisplatin for completely resected pathological stage II/IIIA non-small cell lung cancer[published online August 19, 2018]. Lung Cancer. doi: 10.1016/j.lungcan.2018.08.015