 Patients diagnosed with cancer at the Center for Cancer and Blood Disorders will have a catheter inserted for cancer related treatment. After insertion, eligible patients who provide consent will be enrolled in the diagnosis component of the study. The principal investigator and research team will monitor for catheter complications occlusion and bacteremiafungemia. After two complications, participants will be screened for occult CVC-related DVT by contrast venography, ultrasonography, or magnetic resonance venography. If DVT is not diagnosed, participant will go off the study. If DVT is diagnosed, participant will be asked to consent to enroll in the treatment study. After enrollment, participant is randomized between the two arms of observation and enoxaparin treatment. After 6 weeks, patients will have another image; this represents the end of treatment period. After the follow-up imaging, patients will be monitored for 10 weeks to obtain primary outcomes. Once a primary outcome progression to symptomatic DVT PE, blood stream infection or catheter removal is achieved the participants can be treated with anticoagulation again if necessary, but primary oncologist will determine treatment. 