Vascular surgeons are frequently consulted to optimize hospital care among patients identified with de novo DVT, PE, and VTE. Often, such care features surgical oncology patients having undergone operative resection. Although there is a widespread recognition for associated hypercoaguability among patients with malignancy, less is known about the potential variation in thrombotic complications in this presumptive high-risk group. Moreover, despite potential variations in the risk of VTE among patients with different cancer diagnoses, there are few variations in prophylactic care to prevent these morbid complications. This study demonstrates that the risks of DVT, PE, and concordantly VTE, vary across the spectrum of neoplastic diagnoses. Specifically, these data suggest that patients undergoing prostatectomy, esophagectomy, hysterectomy, and hepatectomy for cancer are at increased risk of VTE. Interestingly, hospital length of stay appears to be one of the greatest risk factors associated with VTE.
Intuitively, patients undergoing cancer surgery remain at a high risk for VTE as they meet criteria for Virchow’s triad of hypercoaguability, stasis, and endothelial injury. Furthermore, cancer has been shown in prior population-based studies to carry a fourfold increased risk of VTE.6,12
The pathophysiology of hypercoagulability in cancer remains complex and likely involves a series of cytokine signaling, abnormal fibrinolysis, and dysfunctional platelet adhesion.13
In addition, surgical resection may carry as much as a 22-fold increased risk of VTE,6
which may still be augmented by varying cancer type, adjuvant chemotherapy, and the requisite need for indwelling catheters.13
Several studies have documented that the risk of VTE varies by the type of cancer.5,8,14
Across studies, pancreatic, brain, lung, stomach, and hematologic malignancies remain associated with a higher risk of VTE. In contrast, head and neck cancers, as well as breast malignancies, although still greater than control, appear to have a lower associated thrombotic risk. Interestingly, although perhaps not surprisingly, the presence of metastatic disease may double the risk of VTE.8
This study demonstrates that the risk of VTE also appears to vary by cancer procedure, in addition to cancer type. Yet our analysis demonstrates that previously perceived lower-risk malignancies such as prostate cancer, esophageal cancer, and liver cancer may actually carry a higher risk of VTE than previously believed. This finding may be due to several differences in our study compared with others. Previous studies have been predominantly epidemiologic in nature5,8
and not specific to patients in the perioperative period. ACS-NSQIP represents a special population of cancer patients, and their risk of VTE likely reflects a combination of both their specific cancer type as well as the magnitude of their surgery. Thus, it is not unexpected for example, that esophageal cancer may carry a more significant increased risk of VTE, as this diagnosis often requires an anatomic resection in both the abdomen and thorax. Therefore, we believe these findings represent a novel analysis of VTE risk among cancer patients.
The current American College of Chest Physicians guidelines recommend pharmacologic VTE prophylaxis for patients with multiple risk factors for thrombotic complications and for those undergoing moderate to major risk surgical procedures. Patients at low risk and undergoing low-risk procedures do not require routine chemical prophylaxis. Ongoing pharmacologic prophylaxis, however, remains recommended for hospitalized cancer patients following surgery, or those who are felt to be medically high risk or bedridden.1
Interestingly, there is currently no variation in method or duration of prophylaxis among cancer types, oncological procedures, or length of stay despite a clear disparity in the risk of sustaining a thrombotic event. Although length of stay alone as a risk factor for the development of a DVT is not well established, the association of prolonged hospitalization, increased cost, and mortality referable to VTE is well known. Specifically, VTE may result in an additional 5 days of hospitalization, an increased cost of $20,000, and a 6% increased mortality on average based on National Inpatient Sample data.15
Based on these findings, this study may assist efforts to reduce VTE events in postoperative cancer patients, by minimizing length of stay, including proper risk stratification, vigilant prophylaxis, minimizing postoperative infectious complications, and minimizing requisite transfusions.
Although Merkow et al previously demonstrated a variation in the incidence of VTE in a similar patient population, the study focused more on associated rates of postdischarge VTE in an effort to recognize the potential need for prolonged prophylaxis.16
This study, in contrast, highlights the perioperative factors that may predispose patients to VTE. Thus, the model incorporated herein utilized additional variables, such as length of stay, which has been shown to increase the risk of DVT.17–19
Length of stay is also a reflection of surgical magnitude and an effect of overall complication rates. As these data point out, prolonged hospital stay is a major risk factor for VTE, which may reflect extended bed rest and associated venous stasis. Thus, our estimates of risk across cancer surgeries are more conservative as we have incorporated these important perioperative variables.
This study has several important limitations. Using these retrospective data, we remain unable to prove causation between specific malignancy resection and thrombotic complications but rather only association. In addition, specific patient-level data remain unavailable within the ACS-NSQIP public use file. Accordingly, we remain unable to identify patients with prior VTE, who may be at higher risk for a second event. Furthermore, specific VTE prophylaxis, such as specific pharmacologic protocols, inferior vena cava filter use, or sequential compression device use, may vary by both surgeon and facility, which could impact the observed rates of variation. Lastly, anatomic features of DVTs (upper vs lower extremity) or the presence of indwelling catheters remain unknown, which may confound these results. Nevertheless, these results do depict variation in thrombotic events associated with various malignancies in real-world contemporary practice. Moreover, this analysis has identified both higher-risk surgeries and independent predictors of DVT, PE, and VTE, which may be considered in an attempt to diminish the incidence of these morbid complications. These results may be used to develop prospective cohort studies designed to validate risk of VTE in patients undergoing various cancer surgeries. This will then be able to overcome the limitations of observational data.