RATIONALE: Dalteparin may be effective in inhibiting the growth of blood vessels in tumors, decreasing the risk of metastatic cancer, preventing the formation of blood clots, and improving quality of life in treating patients with advanced cancer that has not responded to previous treatment. It is not yet known if standard therapy is more effective with or without dalteparin in treating advanced breast, lung, colorectal, and prostate cancer.

PURPOSE: Randomized double blinded phase III trial to compare the effectiveness of standard therapy with or without dalteparin in treating patients who have advanced breast, lung, colorectal, or prostate cancer that has not responded to previous chemotherapy or hormone therapy.

OBJECTIVES: I. Compare the effect of low molecular weight heparin (dalteparin) plus standard therapy versus standard therapy alone on the overall survival rate of patients with advanced cancers. II. Compare the toxic effects of these regimens and the effect on the quality of life of these patients. III. Assess the incidence of symptomatic thrombotic events such as deep venous thrombosis (DVT), pulmonary embolus (PE), and clotted catheters in these patients.

OUTLINE: This is a randomized study. Patients are stratified according to prognostic index (good vs bad vs unsure), current therapy (systemic vs radiation vs both vs none), age (50 or under vs over 50), disease site (breast vs colon vs small cell lung vs nonsmall cell lung vs prostate), history of prior thrombotic event over 1 year ago (yes vs no), and gender. Patients are randomized to receive low molecular weight heparin (dalteparin) plus standard therapy or standard therapy alone.

DISEASE CHARACTERISTICS: Histologically or cytologically proven breast, lung, colorectal, or prostate cancer that has failed prior chemotherapy or hormone therapy No active CNS metastases Hormone receptor status: Not specified

PATIENT CHARACTERISTICS: Age: 18 and over Menopausal status: Not specified Performance status: ECOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: WBC at least 3500/mm3 Platelet count at least 150,000/mm3 Fibrinogen above lower limits of normal Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) SGOT no greater than 3 times ULN Prothrombin time no greater than 1.5 times ULN Active partial thromboplastin time no greater than 1.5 times ULN Renal: Creatinine no greater than 1.5 times ULN Other: No history of heparin associated thrombocytopenia At least 1 year since prior thromboembolic phenomenon such as deep venous thrombosis, pulmonary embolus, or clotted catheter No prior intolerance of unfractionated or low molecular weight heparin

PRIOR CONCURRENT THERAPY: No concurrent anticoagulation therapy No concurrent enrollment on systemic or radiation therapy study (therapy off study allowed)