Incidence of Blood Clots in Patients Undergoing Chemotherapy for Solid Tumors

DISEASE CHARACTERISTICS:

* Cytologically or histologically confirmed diagnosis of 1 of the following:

  * Metastatic breast cancer
  * Colorectal cancer
  * Gastric cancer
  * Lung cancer
  * Ovarian cancer
  * Pancreatic cancer
  * Hormone-refractory prostate cancer
* Scheduled to undergo chemotherapy for ≥ 3 months

  * Chemotherapy for colorectal, gastric, lung, ovarian, or pancreatic cancer may be administered in the neoadjuvant, adjuvant, or palliative setting
* History of deep vein thrombosis or pulmonary embolism allowed if treatment and secondary prevention of the last episode was completed prior to study entry

  * Negative baseline bilateral compression ultrasonography

PATIENT CHARACTERISTICS:

* Life expectancy \> 3 months

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* More than 6 weeks since prior chemotherapy\*

  * Hormonal therapy alone is not considered chemotherapy
* More than 4 weeks since prior major surgery, including surgery for cancer

  * Minor surgery (e.g., implant of a port-a-cath) within the past 4 weeks allowed
* No concurrent major surgery, including surgery for cancer, during the observation period
* Radiotherapy before or during the observation period allowed
* Concurrent chemotherapy\* in combination with additional hormonal therapy allowed
* Concurrent treatment (with the exception of antithrombotic therapy) in any other clinical trial allowed
* No concurrent or scheduled use of thromboprophylaxis or any anticoagulant therapy, including any of the following:

  * Parenteral anticoagulants (e.g., heparin, low molecular-weight heparin, or other agents, such as fondaparinux or bivalirudin)
  * Oral anticoagulants (e.g., vitamin K antagonists)
  * Thrombolytic agents

    * Chronic treatment with antiplatelet agents, such as low-dose aspirin (≤ 300 mg/day) or clopidogrel allowed NOTE: \*Chemotherapy is defined as treatment with any antineoplastic agent, including biologicals