Additional updates
CNS metastases. The anticoagulation recommendations were also updated to include patients with metastatic central nervous system malignancies (those with primary CNS malignancies were included previously). Both those with primary and metastatic CNS malignancy should be offered anticoagulation for established VTE as described for patients with other types of cancer. However, the panel stressed that “uncertainties remain about choice of agents and selection of patients most likely to benefit.”
“Patients with intracranial tumors are at increased risk for thrombotic complications and intracranial hemorrhage (ICH), but the presence of a stable or active primary intracranial malignancy or brain metastases is not an absolute contraindication to anticoagulation,” they wrote.
Limited evidence suggests that therapeutic anticoagulation does not increase ICH risk in patients with brain metastases, but it may increase risk in those with primary brain tumors, the panel added.
Additionally, preliminary data from a retrospective cohort of patients with metastatic brain disease and venous thrombosis suggest that DOACs may be associated with a lower risk of ICH than is LMWH in this population.
Long-term postoperative LMWH. Extended prophylaxis with LMWH for up to 4 weeks is recommended after major open or laparoscopic abdominal or pelvic surgery in cancer patients with high-risk features, such as restricted mobility, obesity, history of VTE, or with additional risk factors. Lower-risk surgical settings require case-by-case decision making about appropriate thromboprophylaxis duration, according to the update.
A 2014 RCT looking at thromboprophylaxis duration in 225 patients undergoing laparoscopic surgery for colorectal cancer prompted the addition of laparoscopic surgery to this recommendation. In that study, VTE occurred by 4 weeks in nearly 10% of patients receiving 1 week of prophylaxis and in no patients in the 4-week arm. Major bleeding occurred in one versus zero patients in the thromboprophylaxis arms, respectively (Ann Surg. April 2014;259[4]:665-9).
Reaffirmed recommendations
Based on the latest available data, the panel reaffirmed that most hospitalized patients with cancer and an acute medical condition require thromboprophylaxis for the duration of their hospitalization and that thromboprophylaxis should not be routinely recommended for all outpatients with cancer.
The panel also reaffirmed the need for thromboprophylaxis starting preoperatively and continuing for at least 7-10 days in patients undergoing major cancer surgery, the need for periodic assessment of VTE risk in cancer patients, and the importance of patient education about the signs and symptoms of VTE.
Perspective and future directions
In an interview, David H. Henry, MD, said he was pleased to see ASCO incorporate the latest DOAC data into the VTE guideline.
Dr. David H. Henry
The AVERT and CASSINI studies, in particular, highlight the value of using the Khorana Risk Score, which considers cancer type, blood counts, and body mass index to predict the risk of thrombosis in cancer patients and to guide decisions regarding prophylaxis, said Dr. Henry, vice chair of the department of medicine and clinical professor of medicine at Penn Medicine’s Abramson Cancer Center, Philadelphia.
The DOACs also represent “a nice new development in the treatment setting,” he said, adding that it’s been long known – since the 2003 CLOT trial – that cancer patients with VTE had much lower recurrence rates with LMWH versus warfarin (Coumadin).
“Now fast forward to the modern era ... and DOACs now appear to be a good idea,” he said.
Dr. Henry also addressed the recommendation for expanded postoperative LMWH use.
“That I found interesting; I’m not sure what took them so long,” he said, explaining that National Comprehensive Cancer Network and European Society of Medical Oncology recommendations have long stated that, for patients with abdominal cancers who undergo abdominopelvic surgery, DVT prophylaxis should continue for 4 weeks.
Dr. Henry said that a survey at his center showed that those recommendations were “very poorly followed,” with surgeons giving 4 weeks of prophylaxis in just 5% of cases.
“The good news from our survey was that not many people had a VTE, despite not many people following the recommendations, but I must say I think our surgeons are catching on,” he said.
Overall, the updated guideline highlights the importance of considering the “cancer variable” when it comes to VTE prevention and treatment.
“We’ve known forever that when we diagnose a DVT or PE in the outpatient setting – and this is independent of cancer – that you should treat it. Add the cancer variable and we now know that we should worry and try to prevent the VTE in certain high-risk patients, and there are some drugs to do it with,” he said, adding that “you should worry about the person you’ve just provoked [with surgery] as well.”
An important question not addressed in the guideline update is the indefinite use of DOACs in cancer patients with ongoing risk, he said.
“When we see DVT or PE, we usually treat for 3 months – that’s the industry standard – and at the end of 3 months ... you do a time out and you say to yourself, ‘Was this person provoked?’ ” he said.
For example, if they took a long flight or if pregnancy was a factor, treatment can usually be safely stopped. However, in a cancer patient who still has cancer, the provocation continues, and the patient may require indefinite treatment.
Questions that remain involve defining “indefinite” and include whether (and which of) these drugs can be used indefinitely in such patients, Dr. Henry said.
Dr. Key reported receiving honoraria from Novo Nordisk, research funding to his institution from Baxter Biosciences, Grifols, and Pfizer, and serving as a consultant or advisor for Genentech, Roche, Uniqure, Seattle Genetics, and Shire Human Genetic Therapies. Numerous disclosures were also reported by other expert panel members.