In a study of women with high-grade uterine cancer, researchers at MD Anderson Cancer Center found sentinel lymph node (SLN) mapping accurately identified all women with node-positive, high-risk uterine cancer, when prospectively compared to a complete pelvic and para-aortic lymphadenectomy (LAD), the current standard of care.
The study offers promise that the less-invasive procedure may one day serve as a staging tool for the most common gynecological malignancy — as it does now for other cancers — with fewer associated risks and complications to patients.
According to the American Cancer Society, 54,870 women will be diagnosed with uterine cancer in 2015, and 10,170 will die from the disease. It’s the most common gynecological cancer, says Soliman, and with its strong association with obesity, there’s been an increase both in overall incidence as well as the number of younger women diagnosed with disease.
For women with uterine cancer, the current standard of care for initial evaluation usually involves a hysterectomy and complete LAD. However, in addition to obesity, other risk factors associated with the disease include diabetes and hypertension. These comorbidities inherently can make surgery more difficult and put women at higher risk for complications such as lymphedema and swelling, explains Soliman.
SLN mapping involves the use of dyes and/or radioactive substances to identify the first lymph nodes in which the cancer is most likely to spread. Hypothetically, cancer should appear in the sentinel node before other nodes and places in the body, says Soliman.
As the technique has been proven and accepted for the staging of diseases such as breast and vulva cancers and melanoma, other institutions have looked at the technique in uterine cancer. Yet the MD Anderson research is the first validation study in which patients received both the mapping and the complete LAD.
“It was important for us to understand that if we performed only the sentinel lymph node mapping, there would be patients who wouldn’t be identified with appropriate disease, as well as to understand the false negatives rate of the technique,” she explains. “If we could still identify patients with positive nodes yet not have to do a full lymphadenectomy, we could potentially decrease the morbidity of the procedure and still appropriately determine post-operative therapy.”
For the single-institution prospective study, MD Anderson is currently enrolling 100 patients with high-risk, grade three uterine cancer. At the meeting, Soliman reported on 73 enrolled patients, 60 of whom were evaluable. The median age and Body Mass Index of the women was 61.1 years and 30.1, respectively. Patients were considered evaluable if SLN mapping was attempted and a full LAD was performed. All of the participants received a PET/CT prior to surgery.
To date, when comparing the mapping results to final surgical pathology, the researchers found that each patient with positive lymph nodes was also found to have a positive SLN — meaning no false negatives were found. In the evaluable women, the researchers were able to identify at least one positive SLN and bilateral SLN in 92.3% (56) and 60.7% (37) of the patients, respectively. These findings are consistent with other research to date, showing the feasibility of the procedure.
For each patient with a node positive for metastatic disease, at least one SLN was also positive for metastatic disease, for a rate of both specificity and sensitivity of 100%.
With further study, the findings could impact standard of care for women with both high- and low-risk disease, says Soliman.
“This study serves as a proof of principal and based on our early results, finds an acceptable false negative rate,” she explains. “Potentially, if we continue to see such promising results, and can identify patients with positive nodes by sentinel lymph node mapping only, it could change practice for the overall management of the endometrial cancer’s general population, much like we have for others diseases.”
Soliman and her colleagues will continue to enroll patients with high-risk endometrial cancer, and the study of SLN in women with early-stage, low-risk disease is ongoing.