Survey of the clinical practice pattern of using sentinel lymph node biopsy in patients with gynecological cancers in Japan: the Japan Society of Gynecologic Oncology study

Long-term outcomes of sentinel lymph node navigation surgery for early-stage cervical cancer

BACKGROUND

Sentinel lymph node navigation surgery, which identifies the sentinel lymph node in early cervical cancers and omits systemic pelvic lymphadenectomy in cases where no lymph node metastasis is present, has recently gained attention. However, there are few reports on lymph node recurrence and the long-term outcomes of cervical cancer surgery performed using sentinel lymph node navigation surgery. In this study, we aimed to evaluate the long-term outcomes of sentinel node navigation surgery for early-stage cervical cancer.

METHODS

One hundred thirty-eight patients with cervical cancer were enrolled. Sentinel lymph nodes were identified by injecting 99 m Technetium-labeled phytate and indocyanine green into the uterine cervix. Surgery and survival outcomes were also analyzed.

RESULTS

The median age and body mass index of the patients were 40 years (20-78) and 21.7 kg/m2 (16.5-50.4), respectively. Open surgery, laparoscopic surgery, and robotic surgery were performed in 77 (56%), 53 (38%), and 8 (6%) patients, respectively. The overall and bilateral detection rates of the sentinel lymph node were 100% and 94%, respectively. Only one case (0.7%) exhibited lower extremity lymphedema, and pelvic lymphocele was observed in three cases (2.2%). Four cases (3%) experienced recurrence over a median follow-up of 57.5 months (range, 2-115 months), with five-year recurrence-free and overall survival rates of 97% and 97.3%, respectively.

CONCLUSIONS

Our results demonstrate that sentinel node navigation surgery may be safe and effective for early-stage cervical cancer.

Development of novel tracers for sentinel node identification in cervical cancer

Indocyanine green (ICG) with near-infrared (NIR) fluorescence imaging is used for lymphatic mapping. However, binding of ICG to blood proteins like serum albumin can shorten its retention time in sentinel lymph nodes (SLNs). Here, we investigated the efficacy and safety of a new fluorescence tracer comprising phytate and liposome (LP)-encapsulated ICG. Coadministration of phytate with LP containing phosphatidic acid promotes chelation mediated by Ca2+ in bodily fluids to enhance SLN retention. Uniformly sized LPs (100 nm) encapsulating ICG under conditions that minimized fluorescence self-quenching during storage were produced. We analyzed the behavior of the new tracer (ICG-phytate-LP) and control tracers (ICG and ICG-LP) in the lymphatic flow of mice in terms of lymph node retention time. We also tested lymphatic flow and safety in pigs that have a more human-like lymphatic system. LPs encapsulating stabilized ICG were successfully prepared. Mixing LP with phytate in the presence of Ca2+ increased both the particle size and negative surface charge. In mice, ICG-phytate-LP had the best lymph node retention, with a fluorescence intensity ratio that increased over 6 h and then decreased slowly over the next 24 h. In pigs, administration of ICG and ICG-phytate-LP resulted in no death or weight loss. There were no obvious differences between blood test results for the ICG and ICG-phytate-LP groups, and the overall safety was good. ICG-phytate-LP may be a useful new tracer for gynecological cancers that require time for lymph node identification due to a retroperitoneal approach.

The Role of Sentinel Lymph Node Mapping in High-grade Endometrial Cancer

OPINION STATEMENT

Total hysterectomy with lymph node assessment is the current standard-of-care for surgical staging in apparent early-stage endometrial cancer. Compared to the traditional complete pelvic lymphadenectomy with or without para-aortic lymphadenectomy, sentinel lymph node (SLN) mapping results in fewer surgical complications, decreased operative time, and lower rates of chronic lymphedema. The technique is endorsed by the National Comprehensive Cancer Network and the Society of Gynecologic Oncology guidelines, and over the past two decades the majority of gynecologic oncologists worldwide have adopted SLN mapping into their practice. However, as the results of the initial SLN studies were mostly based on low-grade tumors, adoption of the technique in high-grade tumors has been slower and more controversial. In this review, we discuss the most recent studies evaluating the SLN mapping in high-grade endometrial cancers. The results of these studies suggest that the SLN detection rate is acceptably high and the negative predictive value is sufficiently low to support the use of SLN mapping in high-grade endometrial tumors to replace complete lymphadenectomy. Validity of SLN mapping techniques does, however, require following a standard algorithm, and success depends also on surgeon expertise. Moreover, the impact of SLN mapping on overall survival in high-grade tumors requires future prospective randomized studies. Finally, a transition toward near-universal SLN mapping techniques for endometrial cancers could significantly impact on the adequacy of gynecologic oncology fellows' surgical training and competency in lymphadenectomy.

Clinical issues of surgery for uterine endometrial cancer in Japan

OBJECTIVE

The mainstay of treatment for uterine endometrial cancer is surgery, and recurrent-risk cases require multidisciplinary treatment, including surgery, chemotherapy and radiation therapy.

METHODS

The standard surgery for uterine endometrial cancer is hysterectomy and bilateral salpingooophorectomy, with additional retroperitoneal lymph node dissection and omentectomy, depending on the case. The appropriate treatment is determined based on the risk classification, such as the depth of invasion into the myometrium, diagnosis of histological type and grade, and risk assessment of lymph node metastasis.

RESULTS

Recently, minimally invasive surgery has been widely used not only in low-risk patients but also in intermediate- and high-risk patients. In low-risk patients, the possibility of ovarian preservation is discussed from a healthcare perspective for young women. Determining the need for retroperitoneal lymph node dissection based on sentinel lymph node evaluation may contribute in minimizing the incidence of post-operative lymphedema while ensuring accurate diagnosis of lymph node metastasis. Recently, many studies using sentinel lymph nodes have been reported for patients with uterine endometrial cancer, and the feasibility of sentinel lymph node mapping surgery has been proven. Unfortunately, sentinel lymph node biopsy and sentinel lymph node mapping surgery have not been widely adopted in surgery for uterine cancer in Japan. In addition, the search for biomarkers, such as RNA sequencing using The Cancer Genome Atlas, metabolic profile and lipidomic profile for early detection and prognostic evaluation, has been actively pursued.

CONCLUSIONS

Gynecologic oncologists expect to be able to provide uterine endometrial cancer patients with appropriate treatment that preserves their quality of life without compromising oncologic outcomes in the near future.