Bortezomib and Gemcitabine in Treating Older Patients With Advanced Solid Tumors

Inclusion Criteria: * Histologically or cytologically confirmed diagnosis of advanced non-hematologic malignancy, including any of the following: * Breast cancer * Lung cancer * Colon cancer * Pancreatic cancer * Head and neck cancer * Sarcoma * Must have failed or become intolerant to prior standard therapy and is no longer likely to respond to such therapy (for all diseases except pancreatic cancer) * Pancreatic cancer patients may be enrolled with no prior therapy requirements since gemcitabine is the current standard of care 1st line therapy * Measurable or nonmeasurable disease * Concurrent enrollment in the University of Minnesota study "Population Pharmacokinetics and Pharmacogenetics of Gemcitabine in Adult Patients with Solid Tumors" (Human Subjects Code 0508M72989) required * ECOG performance status of 0-1 * Absolute neutrophil count ≥ 1,500/mm³ * Platelet count ≥ 100,000/mm³ * Hemoglobin ≥ 10 g/dL * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * Alkaline phosphatase ≤ 3.0 times ULN (5 times ULN if liver has tumor involvement) * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3.0 times ULN (5 times ULN if liver has tumor involvement) * Calculated or measured creatinine clearance \> 30 mL/minute * Fertile patients must use effective contraception during and for 3 months after study participation * Recovered from all prior therapy * Prior systemic chemotherapy, immunotherapy, or biological therapy allowed * At least 3 months…