Objective
Ovarian vein thrombosis is associated with pregnancy and pelvic surgery. Postpartum ovarian vein thrombosis is associated with infection and a high morbidity rate and is treated with anticoagulant and intravenous antibiotic therapy. The natural history of such thrombotic events after debulking surgery for ovarian cancer has not been well described. Our objective was to characterize the presentation and outcomes for patients with this condition at our institution.
Study Design
We conducted a retrospective study of patients who underwent surgical debulking for ovarian cancer at Memorial Sloan Kettering Cancer Center between the years 2001 and 2010. Patients were included if contrast computed tomography scans of both the abdomen and pelvis were performed within 12 weeks before and 12 weeks after the surgery. The images were reviewed to assess for the presence and extent of a new postoperative ovarian vein thrombosis. When available, subsequent studies were assessed for thrombus progression. Medical records were reviewed to determine whether anticoagulation was used for treatment of the thrombotic episode and to record the occurrence of any new significant venous thromboembolic event in the next year.
Results
One hundred fifty-nine patients had satisfactory imaging. New ovarian vein thrombosis was a common complication of debulking surgery, as found in 41 of patients (25.8%). Only 5 women with ovarian vein thrombosis were started on anticoagulation, of which 2 individuals had an independent venous thromboembolic event as indication for treatment. Only 2 of the ovarian vein thromboses (4.9%) progressed to the inferior vena cava or left renal vein on subsequent scan. The estimated cumulative incidence of venous thromboembolism 1 year after the first postoperative scan was 17.1% for patients in the new ovarian vein thrombosis group vs 15.3% of individuals for the group without a postoperative ovarian vein thrombosis ( P = .78).
Conclusion
Ovarian vein thrombosis is commonly encountered after debulking surgery for ovarian cancer. Anticoagulation is usually not indicated, and clinically meaningful thrombus progression rarely occurs.
Ovarian vein thrombosis (OVT) is a rare event that usually is encountered in the postpartum period. It has also been found in association with malignancy, abdominopelvic surgery, inflammatory bowel disease, and pelvic inflammatory disease. Treatment of the pregnancy-associated variant has consisted of antibiotic therapy and anticoagulation, with a low rate of pulmonary embolism. Appropriate management in the setting of cancer has not been established; observation and short-term anticoagulation both are considered acceptable strategies.
Debulking surgery for initial treatment of ovarian cancer usually includes bilateral oophorectomy that results in the formation of a stump at the level of the ovarian veins. Such anatomic change leads to absent blood flow in the affected vessels and a high rate of thrombosis. The effects of local surgical manipulation and thrombophilia that are associated with neoplasia may also contribute to a high rate of OVT in the immediate postoperative period of debulking surgery for ovarian cancer.
Postoperative OVT is typically asymptomatic and identified incidentally on a follow-up, routine contrast enhanced computed tomography (CT) scan. However, the natural history of this complication has not been well-documented, and optimal management remains unclear. Given the high rate of symptomatic lower extremity deep vein thrombosis that is associated with abdominopelvic cancer surgery, going into this project we were concerned that some women might be experiencing clinically significant OVT after debulking for ovarian cancer. We characterized the epidemiologic information and natural history of OVT after debulking for ovarian cancer at our institution to better inform therapeutic decisions in this area.
Methods
This project was deemed exempt from review by the institutional review board based on the low risk to the privacy of individual patients. Informed consent was not obtained based on the retrospective nature of the study and in agreement with the institutional review board. All cases that underwent debulking surgery for ovarian cancer at Memorial Sloan Kettering Cancer Center in the years 2001-2010 were assessed. Data that were captured included date of birth, comorbid conditions, tumor histologic information, last follow-up examination, and survival. This information was entered prospectively at the occasion of clinical encounters with the physicians who cared for individual patients. No cases were excluded from entry.
The records were included for this analysis if satisfactory information was available: adequate quality of CT scans of the abdomen and pelvis with intravenous contrast performed within 12 weeks before (baseline) and 12 weeks after debulking surgery. These were reviewed independently by 2 radiologists (D.S. and W.M.) for the presence of OVT with or without extension into the left renal vein or inferior vena cava (IVC). Only patients without a preexisting OVT on preoperative CT scans were included in this analysis.
If a second, postoperative contrast-enhanced CT of the abdomen and pelvis was available, it was reviewed for the progression of an existing OVT into the IVC or left renal vein for right and left ovarian vein thromboses, respectively. Differences in assessment for the presence or absence of OVT for a given study were resolved by a discussion between the radiologists.
The survival status up to 1 year after debulking surgery was assessed from the Memorial Sloan Kettering clinical data system. The latter was also the source of information for diagnosis of any concomitant or new venous thromboembolic (VTE) episode during the observation period and anticoagulant administered if any.
The data were analyzed with the R for Windows statistical platform (version 3.0). The clinical outcomes of the patients who experienced an OVT in the postoperative period were compared with those of the patients who did not. The cumulative incidence of new VTE episodes was assessed with the cmprsk package, treating death as a competing event. The difference in cumulative incidence of new VTE episodes for patients with and without postoperative new OVT was assessed with the use of Gray’s test. Overall survival was estimated with the use of Kaplan-Meier methods, and the difference in survival was assessed with the use of the log-rank test. Fisher exact tests and Wilcoxon rank sum tests were used to compare the characteristics of the 2 groups.
Results
Five hundred seventy-five patients underwent surgical debulking for ovarian cancer between 2001 and 2010. Study analysis was performed on 159 patients (161 patients had adequate preoperative and postoperative contrast enhanced CT scans; we removed 2 patients who had preexisting OVT on the baseline CT scan). Cohen’s Kappa for initial interobserver agreement on the presence of a new OVT was 0.63. All differences were resolved between the 2 radiologists. All records were reviewed for events that occurred up to 1 year after the index postoperative CT. The baseline characteristics of patients are shown in Table 1 : median age was 60 years (range, 37–74 years) in the group of patients with a new OVT, compared with 59.5 years (range, 23–85 years) in the group without an event ( P = .17); 75.6% of patients had stage IIIC ovarian cancer, and 22.0% of patients had stage IV disease in the subset of patients with a new OVT, compared with 72.9% and 22.9%, respectively, for those without thrombosis ( P = .99).
| Characteristic | New ovarian vein thrombosis (n = 41) | No new ovarian vein thrombosis (n = 118) | P value a |
|---|---|---|---|
| Age, y b | 60 (37–74) | 59.5 (23–85) | .17 |
| Stage, n (%) | .99 | ||
| IIIB | 1 (2.4) | 5 (4.2) | |
| IIIC | 31 (75.6) | 86 (72.9) | |
| IV | 9 (22.0) | 27 (22.9) | |
| Hypertension, n (%) | 11 (26.8) | 26 (22.0) | .64 |
| Diabetes mellitus, n (%) | 3 (7.3) | 2 (1.7) | .11 |
| Pulmonary disease, n (%) | 0 | 4 (3.4) | .57 |
| Coronary artery disease, n (%) | 1 (2.4) | 3 (2.5) | .99 |
| Renal disease, n (%) | 1 (2.4) | 2 (1.7) | .99 |
| Congestive heart failure, n | 0 | 0 | NA |
| Dementia, n | 0 | 0 | NA |
| Stroke, n (%) | 0 | 1 (0.8) | .99 |
| Hepatic disease, n (%) | 2 (4.9) | 3 (2.5) | .60 |
| Peripheral vascular disease, n (%) | 1 (2.4) | 1 (0.8) | .45 |
| Weight, kg b | 70.2 (44.5–112) | 64.0 (40.7–134.5) | .063 |
| Height, cm b | 163.0 (150–179) | 160.0 (131–176.5) | .81 |
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