Omitting CTV for Primary Tumor in LS-SCLC

Twice-daily (45 Gy/30 fractions) or once-daily (45 Gy/15 fractions) thoracic radiotherapy after 2-4 cycles of chemotherapy

Carboplatin IV (AUC=5) on day 1 combined with etoposide IV (100mg/m2) on days 1-3, or cisplatin IV (25mg/m2) on days 1-3 combined with etoposide IV (100mg/m2) on days 1-3. Treatment is repeated every 21 days for 4-6 cycles.

A margin of 0.8 cm beyond the gross target volume of primary tumor.

Beginning 4-6 weeks after chemoradiotherapy completion, patients in both arms who achieve a complete or partial response without brain metastasis receive PCI at 25 Gy/10 fractions or 26 Gy/13 fractions, delivered once daily (5 days per week).