Metformin and Temsirolimus in Treating Patients With Metastatic or Unresectable Solid Tumor or Lymphoma

DISEASE CHARACTERISTICS: * Histologically confirmed malignancy, including any of the following types: * Renal cell * Endometrial * Breast * Small cell lung carcinoma * Lymphoma * Metastatic or unresectable disease for which standard curative or palliative measures do not exist or are no longer effective * Measurable disease according to RECIST criteria * No unstable primary CNS tumors or metastases PATIENT CHARACTERISTICS: Inclusion criteria: * ECOG performance status (PS) 0-2 or Karnofsky PS 60-100% * Life expectancy \> 12 weeks * Absolute neutrophil count ≥ 1.5 x 10\^9/L * Platelets ≥ 100 x 10\^9/L * AST ≤ 2.5 times upper limit of normal (ULN) * Serum creatinine ≤ ULN * Serum bilirubin ≤ 1.5 times ULN * Negative pregnancy test * Fertile patients must use effective contraception * Able to understand and willing to sign a written informed consent document Exclusion criteria: * Allergies to or a history of allergic reactions attributed to any other compound of similar chemical or biologic composition to temsirolimus or metformin * Diabetes mellitus (type I or II) * Uncontrolled hypertriglyceridemia (triglyceride levels \> 10 mmol/L) * History of lactic acidosis * Inability to swallow or digest oral medications * Uncontrolled intercurrent illness including, but not limited to, any of the following: * Uncontrolled hypertension * Ongoing or active infection * Symptomatic congestive heart failure * Unstable angina pectoris * Cardiac arrhythmia * Psychiatric illness/social situation that would limit compliance with study requirements * Significant traumatic injury within 21 days prior to treatment PRIOR CONCURRENT THERAPY: Inclusion criteria: * Recovered from all prior therapy * At least 4 weeks since prior chemotherapy or radiotherapy (6 weeks for carmustine or mitomycin C) except low-dose, non-myelosuppressive radiotherapy * No limitation on other prior therapy * Concurrent low-dose anticoagulant (i.e., warfarin) allowed provided INR ≤ 1.1 times ULN * Concurrent full-dose anticoagulant (i.e., warfarin) allowed provided INR is within institutional therapeutic range (usually 2.0-3.0) Exclusion criteria: * Major surgery within the past 21 days * Prior temsirolimus (or other known inhibitors of mammalian target of rapamycin) or metformin * Concurrent combination antiretroviral therapy for HIV-positive patients * Concurrent enzyme-inducing anti-epileptic drugs (EIAEDs) (e.g., phenytoin, carbamazepine, or phenobarbital) or other CYP3A4 inducer (e.g., rifampin or Hypericum perforatum \[St. John's wort\]) * Concurrent investigational or commercial agents or therapies to treat the patient's malignancy * Other concurrent investigational agents other than temsirolimus or metformin