Anticoagulation use and rate of bland thrombus
A total of 10 (20%) patients with tumor thrombus received
anticoagulation in combination with cancer-directed therapies. Patient
and tumor thrombus characteristics are summarized in Table 2. Six
patients received therapeutic doses of anticoagulation and 4 received
prophylactic doses of anticoagulation. The rationale for starting
anticoagulation was symptomatic tumor thrombus in 4 patients: pulmonary
embolism (PE, n=2), renal vein thrombus (RVT, n=1) and lower extremity
pain and swelling (n=1) concomitant to tumor thrombus diagnosis. Patient
6 was a teenager who relapsed with a right atrial thrombus identified on
routine surveillance imaging after completing therapy and achieving
complete remission of osteosarcoma. Despite therapeutic anticoagulation,
she developed a symptomatic PE 1 week later which required urgent
mechanical thrombectomy. Tissue specimen confirmed relapsed osteosarcoma
and the anticoagulant was discontinued. She subsequently died of another
PE. Patient 7 had newly diagnosed Ewing sarcoma treated with upfront
radical nephrectomy and IVC tumor thrombectomy, which was confirmed by
pathology. Routine scans obtained 2 weeks later, showed possible
residual tumor thrombus in IVC surgical site and pulmonary infarcts with
confirmation of PE via CT angiography. She was started on chemotherapy
following the surgery. The finding of thrombus on repeat imaging was
concerning for tumor thrombus vs a component of bland thrombus that
might have developed post thrombectomy. Hence, she was started
therapeutic anticoagulation in addition to chemotherapy for Ewings
sarcoma. After 6 months of therapeutic anticoagulation and chemotherapy,
repeat imaging studies showed complete resolution of IVC thrombus and
PE. She ultimately died due to relapsed disease. Patient 8 had clear
cell sarcoma with extensive tumor thrombus extending from IVC to common
iliac and femoral veins. Chemotherapy was initiated soon after
diagnosis, but anticoagulation was not started at that time. However, he
presented a few weeks later with left lower leg pain and swelling.
Repeat imaging showed the same extensive tumor thrombus and a new
separate small occlusive thrombus in the superficial femoral vein which
could be tumor thrombus vs bland thrombus. Given the patient was
symptomatic, he was started on therapeutic anticoagulation. Leg pain and
swelling resolved after 4 days and anticoagulation was discontinued at
that point. Patient underwent surgical resection and IVC thrombectomy
later and pathology confirmed the finding of tumor thrombus. Finally,
patient 10 was started on therapeutic anticoagulation for occlusive
renal vein tumor thrombus causing elevated creatinine, concerning for
acute kidney injury. He received three months of therapeutic
anticoagulation along with chemotherapy for metastatic embryonal
carcinoma and repeat imaging at the end of three months showed improved
blood flow through the renal vein. The other six patients had an
asymptomatic tumor thrombus. Rationale for initiating anticoagulation in
these patients was to prevent further progression and possible embolism
of the bland thrombus component of the tumor from high risk locations
(IVC and/or right atrium).
The follow up period for the cohort was a median of 13.5 months (range 1
month to 7 years). Of the patients with or without anticoagulation, none
developed a subsequent bland thrombus and/or embolization secondary to
tumor thrombus, although there was uncertainty about one patient:
Patient 7 developed another thrombus post-surgical resection, but
without pathologic exam, it was unknown if this was bland thrombus or a
remnant of the previous tumor thrombus. A single patient developed a
clearly catheter-associated deep vein thrombus not related to tumor
thrombus 1 month after his cancer diagnosis.