The purpose of this study is to examine whether setting test groups of cisplatin + irinotecan + Krestin therapy as first-line treatment and chemotherapy (radiotherapy or radiotherapy + chemotherapy also allowed) combined with Krestin as second-line treatment after exacerbation and comparing with historical control or community control is appropriate as the protocol and regimen for the phase III clinical trial on extensive-stage disease (ED) small cell lung cancer.

To examine whether the following protocol and regimen is appropriate for the phase III clinical trial on extensive-stage disease (ED) small cell lung cancer: set test groups of cisplatin + irinotecan + Krestin therapy as first-line treatment and chemotherapy (radiotherapy or radiotherapy + chemotherapy also allowed) combined with Krestin as second-line treatment after exacerbation, evaluate the efficacy and safety of treatment in a small number of cases, and compare with historical control or community control.

Inclusion Criteria:

• Patients with histologically or cytologically proven small cell lung cancer

• Patients receiving chemotherapy for the first time

• Patients with no indication for radical radiotherapy or surgical resection

• Patients diagnosed as ED* by full staging [chest X ray, chest C, brain CT or MRI, abdominal CT or abdominal ultrasonography, whole body bone scintigraphy (may be replaced by PET/CT)]

  • ED: Patient with distant metastasis including contralateral hilar lymph node metastasis, but ipsilateral pleural effusion without distant metastasis is excluded.

• Patients with lesions measurable or evaluable by the RECIST criteria

• Patients aged from 20 years to below 75 years

• Patients with preserved organ functions as indicated by the following test values (data obtained within 14 days prior to registration) Hemoglobin: ≥9.0 g/dL White blood cell count: ≥4,000/mm3, ≤12,000 /mm3 Neutrophil count: ≥ 2,000/mm3 Platelet count: ≥100,000 /mm3 GOT, GPT: below 2.5 times the upper limit of normal range for individual facility Total bilirubin: ≤1.5 mg/dL Serum creatinine: below the lower limit of normal range for individual facility Creatinine clearance: ≥ 60mL/min Arterial oxygen tension （PaO2）: ≥60 torr (resting)

• Performance status (PS): 0-1

• Absence of serious concurrent cardiac or pulmonary disease

• Patients expected to survive for at least 3 months

• Patients from whom written informed consent can be obtained

Exclusion Criteria:

• Patients with serious infection and other serious complications (including gastrointestinal bleeding and diarrhea)
• Patients with pleural effusion, ascites, or pericardial effusion that requires treatments including puncture drainage and intracavity administration
• Patients showing definite interstitial pneumonitis or pulmonary fibrosis on plain chest radiograph
• Patients manifesting central nervous system symptoms due to brain metastasis at registration
• Patients with active multiple cancers
• Patients who had undergone bone marrow transplantation
• Patients who had undergone peripheral blood stem cell transplantation
• Patients with a history of definite drug allergy
• Pregnant and nursing patients, patients who may be pregnant or who intend to become pregnant
• Male patients with reproductive capacity who have no intention of contraception during the clinical trial
• Patients with poorly controlled diabetes
• Patients who had been administered Krestin in the past
• Others: patients who are judged by the investigator or subinvestigator to be unsuitable as subject