SAN DIEGO (FRONTLINE MEDICAL NEWS) – Lymphadenectomy is unnecessary if sentinel lymph node mapping successfully stages low-grade endometrial cancer, according to researchers from Johns Hopkins University in Baltimore.

Lymphadenectomy guided by frozen section remains common in the United States. But the Johns Hopkins research team found that using sentinel lymph node (SLN) mapping and biopsy instead cuts the rate of lymphadenectomy by 76%, without reducing the detection of lymphatic metastases.

It’s an important finding for cancer patients likely to survive their diagnosis. “We see low-grade patients in the clinic” who’ve had unnecessary lymphadenectomies, “and they are in terrible shape,” said investigator Dr. Abdulrahman Sinno, a gynecologic oncology fellow at Johns Hopkins. Up to half “have horrible side effects,” including crippling lymphedema and pain.

SLN mapping is “an alternative that gives us the information we need for nodal assessment without putting patients at risk. You’ll know if patients have metastases or not. If they fail to map, you do a frozen section, and if you have high-risk features, a lymphadenectomy only on [the side] that didn’t map,” Dr. Sinno said at the annual meeting of the Society of Gynecologic Oncology.

For the past several years, physicians at Johns Hopkins has been doing both SLN mapping for low-grade endometrial cancer as well as frozen sections to decide the need for lymphadenectomy. Using both approaches allowed the investigators to review how patients would have fared if they had gotten only one.

“[We could] safely study the utility of SLN mapping while maintaining the historical standard of using frozen sections to direct the need for lymphadenectomy,” Dr. Sinno said.

SLN mapping outperformed frozen section. Among 114 women, most with grade 1 disease but some with grade 2 or complex atypical hyperplasia, 8 had lymph node metastases. Mapping identified every one, five by standard hematoxylin-eosin staining, and three by ultrastaging. Frozen-section guided lymphadenectomy missed three.

Eighty four (37%) of the 224 hemi-pelvises in the study had lymphadenectomies based on worrisome frozen-section findings. If SNL mapping had been relied on to make the call, lymphadenectomies would have been performed in 20 (9%), a statistically significant difference (P = 0.004).

“Strategies that rely exclusively on uterine frozen section result in significant overtreatment. In the absence of a therapeutic benefit to lymphadenectomy, we believe” this is “unjustifiable when an alternative exists.” At Johns Hopkins these days, “if you map, you’re done,” Dr. Sinno said.

Almost two-thirds of the women had grade 1 endometrial cancer on preoperative histopathology, and about the same number on final pathology. Bilateral SLN mapping was successful in 71 cases (62%) and unilateral mapping in 27 cases (24%). At least one SLN was detected in 98 women (86%).

There were six recurrences after a median follow-up of 15 months. Four were in women who had full pelvic and periaortic lymphadenectomies that were negative. There was also a port site recurrence and a recurrence in an outlying patient with advanced disease. Overall, “recurrence was independent of whether sentinel nodes were applied,” Dr. Sinno said.

Women in the study were a median of 60 years old, with a median body mass index of 33.3 kg/m2.

Dr. Sinno reported having no relevant financial disclosures.