In a Canadian first, researchers at Princess Margaret Cancer Centre found a less invasive surgical procedure can accurately identify whether cancer has spread in patients with an aggressive endometrial cancer.
Led by Drs. Maria Cusimano and Sarah Ferguson, clinician-researchers at the Princess Margaret and University of Toronto (U of T), the study found that a simpler sentinel lymph node biopsy can replace a more invasive and riskier surgical procedure, with a high degree of accuracy to detect cancer metastases or spread.
The less invasive sentinel node biopsy procedure has less risk of surgical complications, such as injury to major blood vessels or nerves, and lymphedema, an uncomfortable swelling of the lower leg that can occur after surgery.
The study enrolled 156 patients with high-grade endometrial cancer – a cancer that begins in the lining of the uterus and tends to grow quickly, leading to a higher risk of spread and recurrence.
Results of the study were published in
JAMA Surgery in the Nov. 11, 2020 online issue.
"This changes how we manage patients with aggressive endometrial cancer," says Dr. Ferguson, a gynecologic-oncologist and surgeon at the Princess Margaret.
"It is a game changer, because we do much less to get the same information about patients' cancer. For our patients, it's so much easier, with more benefits."
Sentinel node biopsy accurately identified cancer spread in 96 per cent of patients
In the study, the researchers, who are also surgeons, performed two different surgical procedures on each patient in succession, but in the same operation. They began with the less invasive sentinel lymph node biopsy, removing one lymph node on each side of the pelvis in each patient.
They then performed the standard surgical procedure, currently used to evaluate endometrial cancer spread in patients, in which surgeons remove up to 25 lymph nodes in a patient. This procedure is longer, riskier, with potentially more long-term effects such as lymphedema.
When comparing the results from the two procedures, they found that sentinel node biopsy accurately identified cancer spread in 96 per cent of patients, with only one patient misclassified by the sentinel node procedure.
This resulted in a low false-negative rate of four per cent, which is similar to results found in breast and melanoma cancers using this same procedure.
A low false negative rate means that the chances of missing someone whose cancer has spread is low.
All patients with high-grade endometrial cancer are at risk of having their cancer spread to their lymph nodes, explains Dr. Ferguson, who is also the Director of Research, Division of Gynecologic Oncology at UHN.
If cancer has spread to lymph nodes, there's a higher risk that the cancer might recur after surgery. This information determines if additional treatment, such as chemotherapy or radiation, is required after surgery.
"Before this study, we were reluctant to use the simpler sentinel node biopsy technique for this high-risk group of patients because of the fear of missing someone whose cancer metastasized," says Dr. Ferguson, noting that the technique has now been adopted in hospitals such as UHN, Sunnybrook Health Sciences Centre, and Trillium Health Sciences.
Study took five years to complete
"This type of study takes a huge amount of effort, but it moves the field forward because we can't adopt this technique without this type of evidence," says Dr. Maria Cusimano, the lead author and a surgical resident in obstetrics and gynecology at U of T, adding that the study took about five years to complete.
"We want patients, specifically women with less common high-grade tumours, to benefit from high quality research. That takes a dedicated approach."
For patients, this means undergoing a surgery that is an hour to 90 minutes shorter, with less likelihood of major surgical complications, and a 10 per cent decrease in risk of getting lymphedema.
"This research improves the overall patient experience," says Dr. Ferguson.
"Lymphedema, for example, is a debilitating side effect of the more invasive, more complex surgery. A leg can swell three times its normal size. Patients can't wear their shoes. Their skin breaks down. It's painful.
"How we impact patients with treatments is vital. We want to give patients a better quality of life, as well as cure their cancer."
Rates of endometrial cancer have been steadily rising for the past 30 years in Canada.
High-grade endometrial cancer makes up 25 per cent of all endometrial cancers, but 70 per cent of all deaths. Although endometrial cancer incidence is increasing in women aged 30 to 49, it is mostly diagnosed in women age 50 and older.
An estimated 7,400 Canadian women were diagnosed with uterine cancer in 2020, and an estimated 1,300 will die from the disease.
The study was supported by the Princess Margaret Cancer Foundation and the McArthur Research Fund of the Department of Obstetrics and Gynecology at the University of Toronto.
