Twice-daily SIB Radiotherapy Versus Standard Radiotherapy for Patients With SCLC

Inclusion Criteria:

* Read the patient information and Sign the informed consent before enrollment
* Either sex, age ≥18 and ≤70
* Histologically or cytologically confirmed SLCL
* Limited stage disease(AJCC, 2009 version 7), stage I-III(T any, N any, M0) that can be safely treated with definitive radiation doses, excludes T3-4 due to multiple lung nodules that are too extensive or have tumor/nodal volume that is too large to be encompassed in a tolerable radiation plan, clinical nonmalignant diagnosis by investigator when the pleural is too few to obtain cytological evidence.
* measurable lesion according RECIST 1.1
* PS ECOG 0-1
* having zero to two cycles of systemic chemotherapy with etoposide and cisplatin (cisplatin 60-80 mg/m2 at day1 or divided into two to three days, etoposide 100-120 mg/m2 at day 1 to 3, Q21d, and the treatment delay between two cycles shouldn't be more than 14days).
* patients especially female patients must satisfy the investigator that they are not pregnant, or are not of childbearing potential, or are using adequate contraception. Man must also use adequate contraception
* adequate haematological function: white blood cell ≥3.0×109/L , neutrophils ≥1.5×109/L, platelet ≥100×109/L, hemoglobin ≥90g/L.
* adequate liver and renal function: total bilirubin ≤1.5 ×upper limit normal , alanine transaminase and aspartate aminotransferase ≤1.5 ×upper limit normal, normal serum creatinine and/or calculated creatinine clearance ≥60ml/min.

Exclusion Criteria:

* prior surgical resection of the primary tumor or prior RT for lung cancer
* mixed small-cell and non-small-cell histological features
* contemporaneous immunotherapy or target therapy
* pregnancy or lactation
* physical or mental disease that could impact treatment plan
* unable to understand the trial, or could not follow the process
* to refuse the sign the informed consent.
* no history of previous malignancy in the past 5 years (except non-melanomatous skin or in situ servix carcinoma)
* be allergic to any known protocol in this trail
* be enrolled in other clinical trial in past 30days