DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed metastatic or inoperable non-small cell lung, breast, or colon cancer or duct cell carcinoma of the exocrine pancreas

• Bidimensionally measurable lesions that are not previously irradiated

  • New lesions that have developed in a previously irradiated field may be used as measurable disease

• No brain metastases

  • Patients with prior brain metastases are allowed provided they have undergone prior resection of metastases and/or 1 prior course of cranial irradiation, have no new sites of brain metastases since then, have no worsening CNS symptoms, and have discontinued prior corticosteroids for at least 30 days

• Hormone receptor status:

  • Not specified

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Sex:

• Not specified

Menopausal status:

• Not specified

Performance status:

• ECOG 0-2

Life expectancy:

• Not specified

Hematopoietic:

• Absolute neutrophil count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3

Hepatic:

• Bilirubin no greater than 2 times upper limit of normal (ULN)
• AST or ALT no greater than 2 times ULN (5 times ULN if due to liver involvement)

Renal:

• Creatinine no greater than 1.5 times ULN

Other:

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 30 days after study participation
• Capable of swallowing intact study medication capsules
• Capable of following instructions regarding study medication or has daily caregiver to administer study medication
• No concurrent serious infection
• No life-threatening illness unrelated to tumor
• No other prior or concurrent malignancy within the past 3 years except nonmelanoma skin cancer or carcinoma in situ of the cervix

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 2 weeks since prior immunotherapy or biologic therapy

Chemotherapy:

• At least 4 weeks since prior cytotoxic chemotherapy
• No more than 1 prior cytotoxic chemotherapy regimen for metastatic non-small cell lung or colon cancer
• No more than 2 prior cytotoxic chemotherapy regimens for breast cancer
• No prior cytotoxic chemotherapy for pancreatic cancer

Endocrine therapy:

• See Disease Characteristics
• At least 2 weeks since other prior hormonal therapy

Radiotherapy:

• See Disease Characteristics
• At least 3 weeks since prior radiotherapy and recovered
• No concurrent radiotherapy

Surgery:

• See Disease Characteristics

Other:

• No other concurrent anticancer agents