Para-Aortic Lymphadenectomy in Ovarian, Endometrial, Gastric, and Bladder Cancers: A Systematic Review of Randomized Controlled Trials

BACKGROUND

Para-aortic lymphadenectomy can be used for both diagnostic and therapeutic purposes as it aids in staging, provides prognostic data, and influences the patient's options for adjuvant therapy. However, there is still contention over its potential in treating cancer. A systematic review of the literature was performed to look into the published randomized controlled studies (RCTs) that have reported the effectiveness of lymphadenectomy.

METHODS

Five different electronic databases, including PubMed, Cochrane Library, Clinical trials.gov, ICTRP, and Embase, were used to conduct a comprehensive search. Original RCTs reporting on the impact of lymphadenectomy on the overall survival in various cancers were included. Information related to the study population, intervention, type of cancer, primary endpoints, and key findings of the study were extracted. Quality assessment of the selected studies was conducted using the Revised Cochrane Risk of Bias Tool Rob 2 for randomized trials.

RESULTS

A total of 1693 citations, with 1511 from PubMed, 80 from the Cochrane Library, 67 from Embase, 18 from ICTRP, and 17 from Clinicaltrials.gov were retrieved. Preliminary screening was performed, and after applying selection criteria, nine articles were included in the final qualitative analysis. The total number of patients was 4231, and the sample size ranged from 70 to 1408. Among these nine studies, four studies were on genital cancers (two ovarian cancers, one endometrial cancer, and one cervical cancer); four on digestive cancers (advanced gastric cancers); and one on urinary cancer (advanced bladder cancer). These studies reported that para-aortic lymphadenectomy did not improve overall survival and disease-free survival in advanced ovarian cancers, early endometrial cancers, advanced gastric, and bladder cancers. All of the studies had a low risk of bias.

CONCLUSIONS

Para-aortic lymphadenectomy is not advised in advanced ovarian cancers, early endometrial cancers with low risks, advanced gastric cancers, and bladder cancers. SNB could be an alternative to lymphadenectomy for ovarian cancer in the future. Clinicians should inform patients regarding the benefits of para-aortic lymphadenectomy in terms of survival and the potential risks associated with it.

Applications and Safety of Sentinel Lymph Node Biopsy in Endometrial Cancer

Lymph node status is important in predicting the prognosis and guiding adjuvant treatment in endometrial cancer. However, previous studies showed that systematic lymphadenectomy conferred no therapeutic values in clinically early-stage endometrial cancer but might lead to substantial morbidity and impact on the quality of life of the patients. The sentinel lymph node is the first lymph node that tumor cells drain to, and sentinel lymph node biopsy has emerged as an acceptable alternative to full lymphadenectomy in both low-risk and high-risk endometrial cancer. Evidence has demonstrated a high detection rate, sensitivity and negative predictive value of sentinel lymph node biopsy. It can also reduce surgical morbidity and improve the detection of lymph node metastases compared with systematic lymphadenectomy. This review summarizes the current techniques of sentinel lymph node mapping, the applications and oncological outcomes of sentinel lymph node biopsy in low-risk and high-risk endometrial cancer, and the management of isolated tumor cells in sentinel lymph nodes. We also illustrate a revised sentinel lymph node biopsy algorithm and advocate to repeat the tracer injection and explore the presacral and paraaortic areas if sentinel lymph nodes are not found in the hemipelvis.

Should Endometrial Cancer Treatment Be Centralized?

Endometrial cancer (EC) is the most common malignancy of the female genital tract in Western and emerging countries. In 2012, new cancer cases numbered 319,605, and 76,160 cancer deaths were diagnosed worldwide. ECs are usually diagnosed after menopause; 70% of ECs are diagnosed at an early stage with a favorable prognosis and a 5-year overall survival rate of 77%. On the contrary, women with advanced or recurrent disease have extremely poor outcomes because they show a low response rate to conventional chemotherapy. EC is generally considered easy to treat, although it presents a 5-year mortality of 25%. Though the guidelines (GLs) recommend treatment in specialized centers by physicians specializing in gynecologic oncology, most women are managed by general gynecologists, resulting in differences and discrepancies in clinical management. In this paper we reviewed the literature with the aim of highlighting where the treatment of EC patients requires gynecologic oncologists, as suggested by the GLs. Moreover, we sought to identify the causes of the lack of GL adherence, suggesting useful changes to ensure adequate treatment for all EC patients.

Sentinel Lymph Node Mapping in High-Grade Endometrial Cancer

Sentinel lymph node (SLN) mapping is becoming an acceptable alternative to full lymphadenectomy for evaluating lymphatic spread in clinical stage I endometrial cancer (EC). While the assessment of pelvic and para-aortic lymph nodes is part of the surgical staging of EC, there is a long-standing debate over the therapeutic value of full lymphadenectomy in this setting. Although lymphadenectomy offers critical information on lymphatic spread and prognosis, most patients will not derive oncologic benefit from this procedure as the majority of patients do not have lymph node involvement. SLN mapping offers prognostic information while simultaneously avoiding the morbidity associated with an extensive and often unnecessary lymphadenectomy. A key factor in the decision making when planning for EC surgery is the histologic subtype. Since the risk of lymphatic spread is less than 5% in low-grade EC, these patients might not benefit from lymph node assessment. Nonetheless, in high-grade EC, the risk for lymph node metastases is much higher (20–30%); therefore, it is crucial to determine the spread of disease both for determining prognosis and for tailoring the appropriate adjuvant treatment. Studies on the accuracy of SLN mapping in high-grade EC have shown a detection rate of over 90%. The available evidence supports adopting the SLN approach as an accurate method for surgical staging. However, there is a paucity of prospective data on the long-term oncologic outcome for patients undergoing SLN mapping in high-grade EC, and more trials are warranted to answer this question.

Sentinel node biopsy for diagnosis of lymph node involvement in endometrial cancer

BACKGROUND

Pelvic lymphadenectomy provides prognostic information for those diagnosed with endometrial (womb) cancer and provides information that may influence decisions regarding adjuvant treatment. However, studies have not shown a therapeutic benefit, and lymphadenectomy causes significant morbidity. The technique of sentinel lymph node biopsy (SLNB), allows the first draining node from a cancer to be identified and examined histologically for involvement with cancer cells. SLNB is commonly used in other cancers, including breast and vulval cancer. Different tracers, including colloid labelled with radioactive technetium-99, blue dyes, e.g. patent or methylene blue, and near infra-red fluorescent dyes, e.g. indocyanine green (ICG), have been used singly or in combination for detection of sentinel lymph nodes (SLN).

OBJECTIVES

To assess the diagnostic accuracy of sentinel lymph node biopsy (SLNB) in the identification of pelvic lymph node involvement in women with endometrial cancer, presumed to be at an early stage prior to surgery, including consideration of the detection rate.

SEARCH METHODS

We searched MEDLINE (1946 to July 2019), Embase (1974 to July 2019) and the relevant Cochrane trial registers.

SELECTION CRITERIA

We included studies that evaluated the diagnostic accuracy of tracers for SLN assessment (involving the identification of a SLN plus histological examination) against a reference standard of histological examination of removed pelvic +/- para-aortic lymph nodes following systematic pelvic +/- para-aortic lymphadenectomy (PLND/PPALND) in women with endometrial cancer, where there were sufficient data for the construction of two-by-two tables.

DATA COLLECTION AND ANALYSIS

Two review authors (a combination of HN, JM, NW, RG, and WH) independently screened titles and abstracts for relevance, classified studies for inclusion/exclusion and extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We calculated the detection rate as the arithmetic mean of the total number of SLNs detected out of the total number of women included in the included studies with the woman as the unit of analysis, used univariate meta-analytical methods to estimate pooled sensitivity estimates, and summarised the results using GRADE.

MAIN RESULTS

The search revealed 6259 unique records after removal of duplicates. After screening 232 studies in full text, we found 73 potentially includable records (for 52 studies), although we were only able to extract 2x2 table data for 33 studies, including 2237 women (46 records) for inclusion in the review, despite writing to trial authors for additional information. We found 11 studies that analysed results for blue dye alone, four studies for technetium-99m alone, 12 studies that used a combination of blue dye and technetium-99m, nine studies that used indocyanine green (ICG) and near infra-red immunofluorescence, and one study that used a combination of ICG and technetium-99m. Overall, the methodological reporting in most of the studies was poor, which resulted in a very large proportion of 'unclear risk of bias' ratings. Overall, the mean SLN detection rate was 86.9% (95% CI 82.9% to 90.8%; 2237 women; 33 studies; moderate-certainty evidence). In studies that reported bilateral detection the mean rate was 65.4% (95% CI 57.8% to 73.0%) . When considered according to which tracer was used, the SLN detection rate ranged from 77.8% (95% CI 70.0% to 85.6%) for blue dye alone (559 women; 11 studies; low-certainty evidence) to 100% for ICG and technetium-99m (32 women; 1 study; very low-certainty evidence). The rates of positive lymph nodes ranged from 5.2% to 34.4% with a mean of 20.1% (95% CI 17.7% to 22.3%). The pooled sensitivity of SLNB was 91.8% (95% CI 86.5% to 95.1%; total 2237 women, of whom 409 had SLN involvement; moderate-certainty evidence). The sensitivity for of SLNB for the different tracers were: blue dye alone 95.2% (95% CI 77.2% to 99.2%; 559 women; 11 studies; low-certainty evidence); Technetium-99m alone 90.5% (95% CI 67.7% to 97.7%; 257 women; 4 studies; low-certainty evidence); technetium-99m and blue dye 91.9% (95% CI 74.4% to 97.8%; 548 women; 12 studies; low-certainty evidence); ICG alone 92.5% (95% CI 81.8% to 97.1%; 953 women; 9 studies; moderate-certainty evidence); ICG and blue dye 90.5% (95% CI 63.2.6% to 98.1%; 215 women; 2 studies; low-certainty evidence); and ICG and technetium-99m 100% (95% CI 63% to 100%; 32 women; 1 study; very low-certainty evidence). Meta-regression analyses found that the sensitivities did not differ between the different tracers used, between studies with a majority of women with FIGO stage 1A versus 1B or above; between studies assessing the pelvic lymph node basin alone versus the pelvic and para-aortic lymph node basin; or between studies that used subserosal alone versus subserosal and cervical injection. It should be noted that a false-positive result cannot occur, as the histological examination of the SLN is unchanged by the results from any additional nodes removed at systematic lymphadenectomy.

AUTHORS' CONCLUSIONS

The diagnostic test accuracy for SLNB using either ICG alone or a combination of a dye (blue or ICG) and technetium-99m is probably good, with high sensitivity, where a SLN could be detected. Detection rates with ICG or a combination of dye (ICG or blue) and technetium-99m may be higher. The value of a SLNB approach in a treatment pathway, over adjuvant treatment decisions based on uterine factors and molecular profiling, requires examination in a high-quality intervention study.

Combined pelvic and para-aortic is superior to only pelvic lymphadenectomy in intermediate and high-risk endometrial cancer: a systematic review and meta-analysis

BACKGROUND

Lymph node metastasis is a principal prognostic factor for the treatment of endometrial cancer. Added value of para-aortic lymphadenectomy to only pelvic lymphadenectomy for intermediate/high-risk endometrial cancer patients remains controversial.

OBJECTIVE

A systematic review and meta-analysis was performed to assess the impact of combined pelvic and para-aortic lymph node dissection (PPALND) compared to only pelvic lymph node dissection (PLND) on survival outcomes of intermediate and/or high-risk patients.

STUDY DESIGN

The systematic review and meta-analysis adhered to the PRISMA guidelines for meta-analyses of interventional studies. Pubmed, Scopus, EMBASE and Cochrane were searched up to April 20, 2018. Included studies were those comparing high-risk endometrial cancer patients that had performed pelvic and para-aortic lymph node dissection (PPALND) vs. only pelvic lymph node dissection (PLND) apart from standard procedure (total hysterectomy with bilateral salpingo-oophorectomy, TAHBSO). Primary outcomes of the study were overall survival and disease-free survival rates. Methodological quality of the included studies was assessed using the ROBINS-I tool. Overall quality of the evidence for the primary and secondary outcomes was evaluated as per GRADE guideline using the GRADE pro GD tool.

RESULTS

There were 13 studies identified with 7349 patients included. All studies were retrospective observational as no RCTs or prospective studies adhering to inclusion criteria were retrieved. Combined pelvic and para-aortic lymphadenectomy was associated with 46% decreased risk for death (HR 0.54, 95% CI 0.35-0.83, I² = 62.1%) and 49% decreased risk for recurrence (HR 0.51, 95% CI 0.28-0.93). It was also associated with increased 5-year OS rate (RR 1.13, 95% CI 1.04-0.24, I² = 57.3%) and increased 5-year DFS rate (RR 1.23, 95% CI 1.14-1.31, I² = 85.5) compared with only pelvic lymphadenectomy.

CONCLUSION

Combined pelvic and para-aortic lymphadenectomy is associated with improved survival outcomes compared with only pelvic lymphadenectomy in women with intermediate/high-risk endometrial cancers. Further prospective studies should be performed.