**4. Published guidelines**

114 Deep Vein Thrombosis

(Kahn et al., 2007). Similar findings were also reported in the IMPROVE study in which only 45% of cancer patients who either met the ACCP criteria for requiring prophylaxis or were eligible for enrollment in randomized clinical trials that have shown the benefits of pharmacologic prophylaxis actually received prophylaxis [Tapson et al., 2007]. In another study conducted by our group, two hundred cancer patients with established diagnosis of VTE were identified; majority (91.8%) had advanced-stage cancer at time of VTE diagnosis. In addition to cancer, many patients had multiple coexisting risk factors for VTE with 137 (68.5%) patients had at least three, while 71 (35.5%) had four or more. Overall, 111(55.5%) patients developed lower-extremity DVT while 52 (26%) patients developed PE, other sites accounted for 18%. Almost three quarters of the patients (73.5%) had not received any antecedent prophylaxis. Prophylaxis rate was 23% among patients with >3 risk factors and

50% among the highest risk group with >5 risk factors (Abdel-Razeq et al., 2011).

underutilized.

admitted with.

(Abdel-Razeq et al., 2010).

Compared to surgical patients, decisions on when to offer prophylaxis in cancer patients admitted to medical units is difficult to make (Monreal et al., 2004); medical patients typically have many risk factors, the interaction of which is difficult to quantify. In a recent survey, The Fundamental Research in Oncology and Thrombosis (FRONTLINE), marked differences were seen in the use of thromboprophylaxis for surgical and medical cancer patients, with over 50% of surgeons reporting that they initiated thromboprophylaxis routinely, while most medical oncologists reported using thromboprophylaxis in less than 5% of medical cancer patients (Kakkar et al., 2003). These studies and many others (Chopard et al., 2005; Ageno et al., 2002), demonstrate that VTE prophylaxis in cancer patients is still

Many factors may contribute to the low VTE prophylaxis rate in cancer patients. Obviously, concerns about bleeding especially in patients undergoing active treatment with chemotherapy that can lead to low blood counts is one of these reasons; this issue was evident in our study patients where 113 (18.6%) had prolonged PT and or PTT and another 92 (15.2%) had platelet counts < 100 K (Abdel-Razeq et al., 2001). While these may not represent absolute or even relative contraindications for using anticoagulants for VTE prophylaxis, nevertheless, such factors may prevent physicians from prescribing anticoagulant prophylaxis for cancer patients. Other reasons may include concerns about higher bleeding risks from tumor metastasis in vital structures like the brain. Such patients can be offered mechanical methods if anticoagulants deemed contraindicated. However, the absence of a suitable risk assessment model may also contribute to such low prophylaxis rate; such risk assessment model should take into account the additive or even the synergistic effect of the many other additional risk factors that cancer patients are typically

Caprini et al. had established a risk assessment model to help health professionals in making the decision on when and how to prescribe VTE prophylaxis (Caprini et al., 2001 ; Motykie et al., 2000). Though we found it useful, we faced several limitations when we tried to apply such model in cancer patients. All cancer patients were given the same risk score; while in fact type of cancer, stage, nature of anti-cancer therapy and time since cancer diagnosis are, as discussed above, important factors that affect VTE rate in cancer patients Several clinical and scientific groups including the ACCP (Geerts et al., 2008), the American Society of Clinical Oncology (ASCO) (Lyman et al., 2007) and the National Comprehensive Cancer Network (NCCN) (Wagman et al., 2008) have established guidelines for VTE prophylaxis in cancer patients. All have different and somewhat conflicting recommendations but all lack a risk assessment model. While the ACCP guidelines were very conservative and advised prophylaxis for cancer patients who are bedridden with an acute medical illness, the NCCN, on the other hand, lowered their threshold for VTE prophylaxis; their most recent updated guidelines stated: ''The panel recommends prophylactic anticoagulation therapy for all inpatients with a diagnosis of active cancer (or for whom clinical suspicion of cancer exists) who do not have a contraindication to such therapy (category 1).'' Their recommendation was based on an assumption that ambulation in hospitalized cancer patients is inadequate to reduce VTE risk (Wagman et al., 2008). The ASCO guidelines published in 2007 have taken a more neutral position by stating in their summary conclusions: "Hospitalized patients with cancer should be considered candidates for VTE prophylaxis with anticoagulants in the absence of bleeding or other contraindications to anticoagulation" (Lyman et al., 2007).
