Concordance Between Intracervical and Fundal Injections for Sentinel Node Mapping in Patients With Endometrial Cancer?: A Study Using Intracervical Radiotracer and Fundal Blue Dye Injections

Cervical versus utero-ovarian ligament injection of the tracer for the pelvic sentinel lymph node mapping in gynecologic oncology: a prospective observational study

OBJECTIVE

In gynecologic oncology, the consolidated injection site for the pelvic sentinel lymph node mapping is the cervix. However, in apparent early-stage ovarian cancer, current trials map the pelvic area injecting the tracers in the utero-ovarian ligament. A different injection site is proposed based on a possible different lymphatic ovarian drainage through the utero-ovarian ligament and uterus and consequently a different pelvic sentinel lymph node mapping than the cervix; however, this was never proven. On that basis, this study aimed to investigate whether injecting the tracer in the utero-ovarian ligament map the same or a different pelvic sentinel lymph node than the cervix.

DESIGN

Prospective observational study.

METHODS

All consecutive women undergoing primary surgery for gynecologic malignancy with planned pelvic sentinel lymph node mapping were enrolled. The cervical injection was performed at 3 and 9 o'clock injecting indocyanine green. Bilateral utero-ovarian ligament injection was performed injecting methylene blue. The probability of detecting the same sentinel lymph node (concordance rate) and the probability of detecting a different sentinel lymph node (discordance rate) in each hemipelvis were compared using the McNemar's exact test.

RESULTS

Out of 36 hemipelvis (18 patients), the overall detection rate with cervical indocyanine green injection was 86.1% (31/36) versus 52.8% (19/36) with utero-ovarian ligament methylene blue injection (p=0.0004). Indocyanine green and methylene blue identified the same sentinel lymph node in all hemipelvis when sentinel lymph node mapping was obtained by both dyes (19/19; concordance rate 100%). No different or additional sentinel lymph nodes were identified by one of the two dyes (0/19; discordance rate 0%). The probability of detecting the same pelvic sentinel lymph node by the two injections sites was significantly higher than the probability of detecting a different pelvic sentinel lymph node (p<0.0001).

LIMITATIONS

The use of two different dyes with known different sentinel lymph node mapping performance impedes to evaluate differences in detection rate attributable to the two injection sites, limiting the comparison only in hemipelvis in which both dyes identified a sentinel lymph node.

CONCLUSIONS

Cervix and utero-ovarian ligament are two sites for the tracer injection that have a higher probability of detecting the same than a different pelvic sentinel lymph node. Given the higher technical challenge in performing the utero-ovarian ligament injection, these results suggest that the injection of the tracer into the cervix could be a more reliable alternative for the pelvic sentinel lymph node mapping in ovarian cancer.

Lymphoscintigraphy in the Time of COVID-19: Effect of Molybdenum-99 Shortage on Feasibility of Sentinel Node Mapping

Background: In the current study, we reported our experience on sentinel node mapping of breast cancer patients during the extreme shortage of Mo99-Tc99m generators using Tc-99m phytate. Methods and Results: During the period from March 7, 2019, to April 18, 2020, due to disruption of molybdenum supply chain, we used low specific activity Tc-99m pertechnetate elute (0.5-2 mCi of ^99mTcO₄ in 5 mL) for each kit preparation. Two or three intradermal periareolar injections were done for each patient (0.02-0.1 mCi/0.2 mL for each injection). Immediately following injection, dynamic lymphoscintigraphy was done. Surgery was done the same day of injection and the axillary sentinel node was sought using a gamma probe. Overall, 35 patients were included in the study. The specific activity of the Tc-99m elute (in 5 mL) used for kit preparation was 2 mCi/10 mg in four, 1.5 mCi/10 mg in eight, 1.25 mCi/10 mg in eight, 1 mCi/10 mg in three, 0.75 mCi/10 mg in five, and 0.5 mCi/10 mg of ^99mTc-Phytate in seven patients. For the first four groups of patients, we used two 0.2 mL injections, while in the latter two groups, three 0.2 mL injections were used. At least one sentinel node was detected in all patients but three in whom axilla was involved. Conclusion: Sentinel node biopsy can be achieved with low specific activity of Tc-99m elute at the time of Mo99-Tc-99m generator shortage. If special personal protection is used, sentinel node mapping can be done in nuclear medicine departments with excellent results despite the COVID-19 pandemic and disruption of generator shipment.

Sentinel lymph node mapping in endometrial cancer: performance of hysteroscopic injection of tracers

OBJECTIVE

To report on the performance of hysteroscopic injection of tracers (indocyanine green (ICG) and technetium-99m (Tc-99m)) for sentinel lymph node (SLN) mapping in endometrial cancer.

METHODS

Single-center retrospective evaluation of consecutive patients who underwent SLN mapping following hysteroscopic peritumoral injection of tracer. Detection rate (overall/bilateral/aortic) diagnostic accuracy, and oncologic outcomes were evaluated.

RESULTS

A total of 221 procedures met the inclusion criteria. Mean patient age was 60 (range 28-84) years and mean body mass index was 26.9 (range 15-47) kg/m² . In 164 cases (70.9%) mapping was performed laparoscopically. The overall detection rate of the technique was 94.1% (208/221 patients). Bilateral pelvic mapping was found in 62.5% of cases with at least one SLN detected and was more frequent using ICG than with Tc-99m (73.8% vs 53.3%; p<0.001). In 47.6% of cases SLNs mapped in both pelvic and aortic nodes, and in five cases (2.4%) only in the aortic area. In eight patients (3.8%) SLNs were found in aberrant (parametrial/presacral) areas. Mean number of detected SLNs was 3.7 (range 1-8). In 51.9% of cases at least one node other than SLNs was removed. Twenty-six patients (12.5%) had nodal involvement: 12 (46.2%) macrometastases, six (23.1%) micrometastases, and eight (30.7%) isolated tumor cells. In 12 cases (46.8%) the aortic area was involved. Overall, 6/221 (2.7%) patients had isolated para-aortic nodes. Three false-negative results were found, all in the Tc-99m group. All had isolated aortic metastases. Overall sensitivity was 88.5% (95% CI 71.7 to 100.0) and overall negative predictive value was 96.5% (95% CI 86.8 to 100.0). There were 10 (4.8%) recurrences: five abdominal/distant, four vaginal, and one nodal (in the aortic area following a unilateral mapping plus side-specific pelvic lymphadenectomy). Most recurrences (9/10 cases) were patients in whom a completion lymphadenectomy was performed. No deaths were reported after a mean follow-up of 47.7 months.

CONCLUSIONS

Hysteroscopic injection of tracers for SLN mapping in endometrial cancer is as accurate as cervical injection with a higher detection rate in the aortic area. ICG improves the bilateral detection rate. Adding lymphadenectomy to SLN mapping does not reduce the risk of relapse.