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