Introduction
Cervical cancer is the second most commonly diagnosed cancer and the third leading cause of cancer-related deaths among females, with significant upward trends in its incidence and mortality1-2. Conventionally, women with early-stage cervical cancer (FIGO 2009 stages Ia2–IIa2) undergo hysterectomy with pelvic lymph node dissection (PLND). However, early-stage cervical cancer with nodal metastases accounts for only 8–26% of cases3, suggesting that approximately more than 75% of those patients routinely undergo unnecessary PLND. PLND increases the incidence of short- and long-term complications, especially leg lymphedema, and removing “healthy” lymph nodes may negatively influence the immune system4. All complications markedly decrease the quality of post-operative life. Hence, avoiding unnecessary PLND in early-stage cervical cancer patients is clinically important.
The so-called sentinel lymph node (SLN) is the first lymph node to drain from a primary tumour5. If SLNs are metastasis-negative, then upstream nodes should (in theory) also be metastasis-free. To reduce the morbidity associated with PLND, SLN biopsy (SLNB) is diagnostically beneficial when assessing for nodal metastases in early-stage cervical cancer6. The National Comprehensive Cancer Network (NCCN) guidelines recommend SLNB as an alternative to PLND (Recommendation 2A)7. However, the implementation of SLNB is limited, especially in China, where one-fourth of the cervical cancer cases in the world occur1. According to an anonymous online survey completed by all full and candidate members of the Society of Gynaecology and Obstetrics (SGO), only 70% (n = 139) of the 198 respondents (response rate = 17.7%) indicated that they perform SLNB. The main reason for not performing SLNB was the lack of standardized training and technology8. Inevitable heterogeneity was observed in patient selection and tracer application in previous studies, which were mainly retrospective studies with small sample sizes. Moreover, there are some disadvantages to using the most common tracers, such as allergic reactions, radioactive pollution, and the cost of and dependence on expensive imaging technology9-11.
Therefore, we investigated carbon nanoparticle suspension (CNS), a new tracer that can be used in SLNB for patients with early-stage cervical cancer. A previous study showed that CNS permits easy identification, has good lymphatic tracer effects, and results in increased lymph node retrieval12. Its use in SLNB for cervical cancer is relatively new. Accordingly, the objectives of this study were to assess the safety and feasibility of CNS in SLNB, and to determine the diagnostic validity of the SLN status for assessing lymphatic spread in early-stage cervical cancer.