ORLANDO—The use of low molecular weight heparin to prevent deep vein thrombosis (DVT) might not be necessary among women who undergo robotic surgery for endometrial cancer, researchers said here at the Annual Meeting on Women‘s Cancer of the Society of Gynecologic Oncology.
Among individuals who did not receive prophylaxis after leaving the hospital following robot-assisted surgery, no cases of venous thromboembolism (VTE) were observed, said Nikki Neubauer, MD, a gynecologic oncology fellow at the Feinberg School of Medicine of Northwestern University in Chicago.
“Given the costs associated with low molecular weight heparin venous thromboembolism prophylaxis and the low incidence of venous thromboembolism noted in our study, extended prophylaxis upon discharge from the hospital does not appear to be warranted for patients undergoing robotic surgery for endometrial cancer.”
Two women who underwent open laparotomy experienced pulmonary emboli during the two-year period of the study; and another women who had extended prophylactic therapy experienced a DVT, said Dr. Neubauer, who presented one of five posters at the meeting that was selected to be highlighted as an oral abstract.
“Prevention of venous thromboembolism is the number one health safety recommendation of the US Department of Health and Human Services Agency for Healthcare Research and Quality in 2001,” Dr. Neubauer said in her slide presentation. “It is one of the complications that hospitals are working hard to prevent.
Women with gynecologic cancer are at increased risk of developing venous thromboembolism both due to the hypercoaguable state associated with malignancy and because of the surgical treatment often required for these conditions.”
She cited studies that indicate that women with gynecologic cancer may have a rate of DVT of 11% to 18% and a risk of pulmonary embolism of 1% to 3%. The optimal prophylaxis for patients with gynecologic cancer undergoing surgical treatment often involves early ambulation, sequential compression devices, and use of low molecular weight heparin.
The occurrence of VTE in patients with endometrial cancer is associated with a doubling of mortality in the disease, Dr. Neubauer noted. “Thus the prevention of venous thromboembolism is an important topic in gynecologic oncology.”
The American College of Chest Physicians currently recommends that patients undergoing major abdominal or pelvic surgery who are over age 60 or who have cancer or a prior diagnosis of VTE should receive extended prophylaxis VTE therapy with low molecular weight heparin for four weeks.
“The method of venous thromboembolism prophylaxis, the duration of therapy, and the need for therapy after minimally invasive surgeries remains to be proven,” she noted, and she and her colleagues therefore sought to compare the rates of VTE between women with endometrial carcinoma who underwent open abdominal hysterectomy and staging procedures and those who were treated with robotic-assisted staging procedures.
The researchers also compared the rates of VTE in women who underwent a minimally invasive procedure and received extensive VTE prophylaxis postoperatively with low molecular weight heparin with those who did not. All the patients received VTE prophylaxis while they were in the hospital.
In the retrospective study conducted at a single institution, Dr. Neubauer and her colleagues identified 114 women who were treated with an open abdominal hysterectomy procedure between January 1, 2007 and June 30, 2009. All 114 of the women received low molecular weight heparin prophylaxis against VTE for four weeks. Two episodes of VTE were diagnosed—about 1.8%
During the same time frame, 210 women underwent robot-assisted surgery. Of that group, 101 were treated with extended low molecular weight heparin prophylaxis for two weeks. One episode of VTE was observed in this group—about 1%. That event occurred about six weeks after undergoing surgery—”well past the time she had taken low molecular weight heparin for prophylaxis,” Dr. Neubauer noted.
The other 109 women did not receive extended low molecular weight heparin prophylaxis, and none had any venous thromboembolism. The difference in the rates of episodes of VTE did not reach statistical significance.
All three of the patients who had VTE had risk factors for developing the blood clots. One of the laparotomy patients had an extended hospital stay of eight days—and a six-hour operation and Stage IVB disease—all increasing the risks of embolic episodes.
The other laparotomy patient was 74 years old, had surgery that lasted more than four hours, and spent six days in the hospital. The patients with deep vein thrombosis was 68, was morbidly obese with a body mass index of 43, and spent more than three and a half hours in surgery.
Dr. Neubauer did note that there were significant differences in the patient population. Those who underwent robotic-assisted surgery and did not receive post-hospitalization prophylaxis were about 56—younger than those who received extended low molecular weight prophylaxis who were about 61. The median age for those who underwent open surgery was 59.
The patients who had the robotic assisted surgery without extended prophylaxis also had a smaller body mass index—28 vs 31 for patients who were put on extended prophylaxis and 34 for those who had open surgery.
In the laparotomy group, 30% of patients had a body mass index greater than 40 compared with 25% of the patients in the robotic group.
Those patients who had robotic-assisted surgery were more likely to have Stage 1A cancer—55% of those receiving extended prophylaxis had Stage 1A cancer compared with 48% who did not have extended prophylaxis. About 35% of patients undergoing open surgery had Stage 1A disease.
Most of the patients in the laparotomy group with a VTE were diagnosed with a pulmonary embolism in the immediate postoperative period prior to discharge from the hospital.
The one woman in the robotic group who had extended prophylaxis was diagnosed with a deep vein thrombosis while on a two-week course of postoperative prophylactic low molecular weight heparin.
“Patients undergoing a robotic minimally invasive surgical procedure are at a lower risk of postoperative venous thromboembolism as compared with patients undergoing an open laparotomy,” Dr. Neubauer said.
In discussing the presentation, Susan C. Modesitt, MD, Associate Professor and Director of the Gynecologic Oncology Division at the University of Virginia, cautioned that the study was retrospective: “The problem with any of us doing retrospective reviews is that they are fraught with all the inherent bias of retrospective reviews.
“When you are looking at such a minute number of events, even though you have a population of a couple of hundred, there is no meaningful data that you can extract to say that one treatment is different from another. The important thing is that the incidence is low no matter what.
“We had a little poll among those of us at the front table and none of us are sending our robotic patients for extended prophylaxis,” Dr. Modesitt said.