It has been previously reported that without thromboprophylaxis, the incidence of symptomatic VTE following major surgery was 1.5-6.0% [12, 13]. In surgical patients with mechanical prophylaxis, administration of heparin, or both of these, the incidence of symptomatic VTE was 0.9–3.4%, 0.5–1.9%, or 0.2–0.9%, respectively [12–16]. These studies also reported that major bleeding was observed in 1.2–4.5% of patients [12, 14, 15]. The incidence of fatal PE in the patients with thromboprophylaxis was reduced to 0.1–0.5%, compared to 0.3–1.2% in the patients without thromboprophylaxis [4]. In the clinical practice guidelines reported by the American College of Chest Physicians and the American Society of Clinical Oncology, the type of thromboprophylaxis was determined according to the risk stratification of VTE and bleeding complications. For patients with a moderate risk of VTE, administration of heparin or mechanical prophylaxis was recommended, while for the patients at a high risk of VTE, the administration of heparin with the addition of IPCD was recommended [4, 17]. However, if the patients were at high risk for major bleeding complications, the administration of heparin was avoided. In this study, all patients were classified as moderate or high risk, as evaluated by the Caprini score. Heparin was only administered to patients with acute or subacute DVT, or with PE before ISBT. This was because ISBT, in which 10 or more needles were placed for 2–3 days, was considered to be a procedure that had a potential for major bleeding. As a result, the incidence of VTE was observed in 2 (4.2%) out of 47 patients, and worsening of VTE was observed in 5 (10.6%) out of 47 patients. However, there was no occurrence of symptomatic VTE, and no major bleeding complications occurred during or after ISBT under thromboprophylaxis in this study.
The risk of VTE appeared to be highest for patients undergoing abdominal or pelvic surgery for malignancy [4, 18, 19]. In addition, advanced age (especially 60 years or older), prior VTE, bed rest (4 days or longer), and longer length of hospital stay were also considered to be risk factors for VTE following surgery [4, 13, 20–22]. Tasaka et al. reported that the risk factors for VTE at pretreatment were advanced age (60 years or older) and bulky tumors (40 mm or greater) for cervical cancer patients, and advanced age, stage III/IV disease, and bulky tumors (60 mm or greater) for endometrial cancer patients [23]. In univariate analysis of this study, advanced age, bulky tumors, and long bed rest were not significantly related to the incidence or worsening of VTE (Table 3). However, the presence of VTE before ISBT, a Caprini score ≥ 6, a difference in DD values between pre-ISBT and the day of needle removal ≥ 1, and a difference between pre-ISBT and the day following needle removal ≥ 1 were risk factors for VTE.
The risk stratification for VTE following surgery was mainly evaluated according to the Rogers score [4, 8] and the Caprini score [4, 9]. The Rogers score was established based on the analysis of VTE incidence in 183,069 patients undergoing vascular and general surgery [8] and consists of patient factors (female gender, higher American Society of Anesthesiologists class, ventilator dependence, preoperative dyspnea and transfusion in the 72 hours before operation), preoperative laboratory values (albumin, bilirubin, sodium and hematocrit), and surgical characteristics (type of surgical procedure, work relative value units, and infected/contaminated wounds). In this study, all patients were categorized as very low risk, because the Rogers score is composed of factors that are less affected by ISBT. In contrast, the Caprini score, which was mainly established by referring to the medical literature, contains patient factors (age, body mass index, prior VTE, family history of VTE, coagulation factors such as Factor V Reiden and Lupus anticoagulant, malignancy, and bed rest) and surgical characteristics (type of surgical procedure). In this study, the incidence or worsening of VTE was significantly higher in the high-risk group, as determined by a Caprini score ≥ 6, than in the high risk group (Caprini score 5) or the moderate risk group (Caprini score 3–4) (p < 0.01). Because factors such as age, bed rest, and prior VTE were included in the Caprini score, it was considered more suitable than the Rogers score to evaluate a risk for the incidence or worsening of VTE during ISBT.
To predict the incidence or worsening of VTE during ISBT, changes in DD values detected by close monitoring and a diagnosis of VTE before ISBT are necessary to screen gynecological cancer patients treated with ISBT. The Caprini score may be useful to predict the incidence or worsening of VTE, not only for the surgical patients but also for the patients treated with ISBT. Additionally, the close monitoring of DD values and the management of VTE that was modelled in this study could be suggested as a novel approach for thromboprophylaxis in gynecological cancer patients treated with ISBT.