Efficacy of platinum-based adjuvant chemotherapy for epidermal growth factor receptor-mutant lung adenocarcinoma.

BACKGROUND

The ADAURA trial reported that osimertinib improved overall survival (OS) as an adjuvant chemotherapy for pathological stage IB-IIIA epidermal growth factor receptor (EGFR) mutant lung cancer compared with a placebo. Currently, platinum-based adjuvant chemotherapy is the standard treatment for patients with or without EGFR mutations. This study aimed to evaluate the efficacy of platinum-based adjuvant chemotherapy in patient with stage II-IIIA EGFR mutant lung adenocarcinoma.

METHODS

We collected the medical records of consecutive patients who underwent surgical resection for lung adenocarcinoma between 2005 and 2012 at the four participating institutions. The data of 173 patients with different EGFR mutation status were retrospectively evaluated to determine the efficacy of platinum-based adjuvant chemotherapy for OS and recurrence-free survival (RFS). We further analyzed OS using the inverse probability of treatment weighting method with propensity scores.

RESULTS

The median age was 69 years (range, 45-85 years); 95 (54.9%) were male and 74 (42.8%) had EGFR mutations. A total of 43 patients with EGFR mutants (58.1%) and 43 patients with wild-type EGFR tumors (43.4%) received platinum-based adjuvant chemotherapy. No differences in RFS and OS were observed between EGFR mutant and wild-type EGFR in lung adenocarcinoma without adjuvant therapy. However, wild-type EGFR showed an improvement in OS with platinum-based adjuvant chemotherapy in inverse probability of treatment weighting analysis, whereas those with EGFR mutations showed no significant difference in OS between the surgery-only group and the adjuvant group. The deletion of exon 19 and exon 21 L858R point mutation showed no significant differences in OS between the surgery-only group and the adjuvant group, respectively. The hazard ratio (HR) exceeded 1 for uncommon EGFR mutations.

CONCLUSIONS

Platinum-based adjuvant chemotherapy may be less effective for EGFR-mutant lung adenocarcinoma, regardless of the mutation type.