211P - Five-year survival outcomes from PIT-2: S-1 plus cisplatin with concurrent radiotherapy followed by surgery in stage IIIA (N2) lung squamous cell carcinoma

Background

Personized Induction Therapy-2 (PIT-2) is a multicenter, phase II trial of S-1 plus cisplatin and concurrent thoracic radiation therapy (TRT) followed by surgery for stage IIIA (N2) lung squamous cell carcinoma (LSCC). The primary endpoint, 2-year progression-free survival (PFS) rate, was 67% (90% confidence interval [CI]; 54–78%). We report exploratory analyses of survival outcomes approximately 5 years after the last patient was enrolled.

Methods

Patients with stage IIIA (pathologically proven N2) LSCC received induction therapy comprising three cycles of S-1 and cisplatin plus concurrent TRT (45 Gy in 25 fractions) followed by surgery. S-1 was administered orally at a dose of 40 mg/m² twice daily for 14 days along with an intravenous infusion of cisplatin (60 mg/m²) on day 1. Five-year overall survival (OS), 5-year PFS, and patterns of postoperative recurrence were analyzed. Prognostic factors for OS were analyzed in surgically resected patients using the Cox proportional hazards model.

Results

The median follow-up was 65.1 months. In 43 treated patients, the 5-year OS and PFS rates were 58.1% (95% CI; 42.0–71.1) and 46.4% (95% CI; 31.1–60.4), respectively. Among the 39 surgically resected patients, pathological complete response and major pathological response were significant prognostic factors for OS (P=0.001 and P < 0.001, respectively). Pathological nodal downstaging was marginally significant (P=0.07). Age, sex, clinical T stage, clinical lymph node status on computed tomography, and preoperative serum CEA and CYFRA levels did not have a significant prognostic impact on OS. The patterns of postoperative recurrence were locoregional only in five (36%), distant metastasis only in six (43%), and both in three (21%) patients. The recurrence in ipsilateral hilar or mediastinal lymph nodes (irradiation field) developed in seven (18%) among 39 surgically resected patients.

Conclusions

Five-year survival outcomes of PIT-2 indicate that induction therapy with S-1 plus cisplatin and concurrent TRT followed by surgery is the optimal treatment for stage IIIA (N2) LSCC, especially for cases contraindicated for immunotherapy.

Clinical trial identification

UMIN: 000012413, jRCT: s031180403.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.