Is Axillary Lymph Node Dissection Necessary After a Positive Sentinel Lymph Node Biopsy?

The Lymphatic System in Breast Cancer: Anatomical and Molecular Approaches

Breast cancer is one of the most important causes of premature mortality among women and it is one of the most frequently diagnosed tumours worldwide. For this reason, routine screening for prevention and early diagnosis is important for the quality of life of patients. Breast cancer cells can enter blood and lymphatic capillaries, then metastasizing to the regional lymph nodes in the axilla and to both visceral and non-visceral sites. Rather than at the primary site, they seem to enter the systemic circulation mainly through the sentinel lymph node and the biopsy of this indicator can influence the axillary dissection during the surgical approach to the pathology. Furthermore, secondary lymphoedema is another important issue for women following breast cancer surgical treatment or radiotherapy. Considering these fundamental aspects, the present article aims to describe new methodological approaches to assess the anatomy of the lymphatic network in the axillary region, as well as the molecular and physiological control of lymphatic vessel function, in order to understand how the lymphatic system contributes to breast cancer disease. Due to their clinical implications, the understanding of the molecular mechanisms governing lymph node metastasis in breast cancer are also examined. Beyond the investigation of breast lymphatic networks and lymphatic molecular mechanisms, the discovery of new effective anti-lymphangiogenic drugs for future clinical settings appears essential to support any future development in the treatment of breast cancer.

Candidates of Genomic Tests in HR+/HER2- Breast Cancer Patients With 1-2 Positive Sentinel Lymph Node Without Axillary Lymph Node Dissection: Analysis From Multicentric Cohorts

Background

The genomic tests such as the MammaPrint and Oncotype DX test are being gradually applied for hormone receptor positive/HER-2 negative (HR+/HER2-) breast cancer patients with up to three positive axillary lymph nodes (ALNs). The first results from RxPONDER trial suggested that Oncotype DX could be applied to patients with 1-2 positive sentinel lymph nodes (SLNs) without axillary lymph node dissection (ALND), which constituted 37.4% of the intent-to-treat population. However, there was no distinctive research on how to apply genomic tests precisely to HR+/HER2- patients with 1-2 positive SLNs without ALND. The purpose was to construct a nomogram using the multi-center retrospective data to predict precisely which HR+/HER2- candidates with 1-2 positive SLNs could be subjected to genomic tests (≤ 3 positive lymph nodes).

Methods

We conducted a retrospective analysis of 18,600 patients with stage I-III breast cancer patients treated with sentinel lymph node biopsy (SLNB) in Shandong Cancer Hospital, Fudan University Shanghai Cancer Center, and West China Hospital. The univariate and multivariate logistic regression analysis was conducted to identify the independent predictive factors of having ≤ 3 positive nodes among patients with 1-2 positive SLNs. A nomogram was developed based on variables in the final model with p<0.05. Calibration of the nomogram was carried out by internal validation using the bootstrap resampling approach and was displayed using a calibration curve. The discrimination of the model was evaluated using the ROC curve.

Results

Based on the database of the three institutions, a total of 18,600 breast cancer patients were identified undergoing SLNB between May 2010 and 2020. Among the 1817 HR+/HER2- patients with 1-2 positive SLNs undergoing ALND, 84.2% harbored ≤ 3 totals metastatic ALNs. The multivariate logistic regression analysis identified imaging abnormal nodes (OR=0.197, 95%CI: 0.082-0.472), the number of positive SLNs (OR=0.351, 95%CI: 0.266-0.464), the number of negative SLNs (OR=1.639, 95%CI: 1.465-1.833), pathological tumor stage (OR=0.730, 95%CI: 0.552-0.964), and lympho-vascular invasion (OR=0.287, 95%CI: 0.222-0.398) as independent predictors for the proportion of patients with ≤ 3 total metastatic ALNs (all p<0.05). These five predictors were used to create a predictive nomogram. The AUC value was 0.804 (95%CI: 0.681-0.812, p<0.001). The calibration curve showed a satisfactory fit between the predictive and actual observation based on internal validation with a bootstrap resampling frequency of 1000.

Conclusion

The nomogram based on the multi-centric database showed a good accuracy and could assist the oncologist in determining precisely which HR+/HER2- candidates with 1-2 positive SLNs without ALND could perform genomic tests. In the era of SLNB and precision medicine, the combined application of genomic tests and SLNB could provide patients with a better strategy of dual de-escalation management, including the de-escalation of both surgery and systemic treatment.

Surgical Management of the Axilla in Elderly Women With Node-Positive Breast Cancer

BACKGROUND

Elderly women with clinically node-positive (cN+) breast cancer (BC) often have comorbidities that limit life expectancy and complicate treatment. We sought to determine whether the number of lymph nodes (LNs) retrieved among older women with node-positive BC was associated with overall survival (OS).

METHODS

Using the National Cancer Database (2010-2015), women 70-90 y with cN + BC and ≥1 LNs removed were categorized by treatment sequence: upfront surgery or neoadjuvant chemotherapy (NAC). Multivariable Cox proportional hazards models with restricted cubic splines characterized the functional association of LN retrieval with OS; threshold values of LN retrieval were estimated. Cox proportional hazards models were used to estimate the association of LN retrieval groups with OS.

RESULTS

In the upfront surgery cohort, a nonlinear association was identified between LNs retrieved and OS. In the NAC cohort, no association was identified. For the upfront surgery cohort, the optimal threshold value of LN retrieval was 21 LNs (90% confidence interval 18-23). Based on this estimate, LN retrieval groups were created: <6, 6-11, 12-17, 18-23, and >23 LNs. After adjustment, retrieval of <12 LNs in the upfront surgery group was associated with a worse OS. No differences were observed in the NAC group.

CONCLUSIONS

For elderly women receiving upfront surgery, there is no survival benefit to removing more than 12 LNs, and for those receiving NAC, there is no association between number of LNs removed and survival. In older women who present with cN + BC, aggressive surgery to remove more than 12 LNs may not be necessary.

Comparing Observation, Axillary Radiotherapy, and Completion Axillary Lymph Node Dissection for Management of Axilla in Breast Cancer in Patients with Positive Sentinel Nodes: A Systematic Review

PURPOSE

Several randomized controlled trials (RCTs) have investigated observation or axillary radiotherapy (ART) in place of completion axillary lymph node dissection (cALND) for management of positive sentinel nodes (SNs) in clinically node-negative women with breast cancer. The optimal treatment strategy for this population is not known.

METHODS

MEDLINE, Embase, and EBM Reviews-NHS Economic Evaluation Database were searched from inception until July 2019. A systematic review and narrative summary was performed of RCTs comparing observation or ART versus cALND in clinically node-negative female breast cancer patients with positive SNs. The Cochrane risk of bias tool for RCTs was used to assess risk of bias. Outcomes of interest included overall survival (OS), disease-free survival (DFS), axillary recurrence, and axillary surgery-related morbidity.

RESULTS

Three trials compared observation with cALND, and two trials compared ART with cALND. No studies blinded participants or personnel, and there was heterogeneity in inclusion criteria, study design, and follow-up. Neither observation nor ART resulted in statistically inferior 5- or 8-year OS or DFS compared with cALND. There was also no statistically significant increase in axillary recurrences associated with either approach. Four trials reported morbidity outcomes, and all showed cALND was associated with significantly more lymphedema, paresthesia, and shoulder dysfunction compared with observation or ART.

CONCLUSIONS

Women with clinically node-negative breast cancer and positive SNs can safely be managed without cALND.

The use of Thiel embalmed human cadavers for retrograde injection and visualization of the lymphatic system

In order to provide an alternative for fresh frozen specimens to map the lymphatic system, the possibility of using Thiel embalmed specimens for this purpose was explored. The thoracic duct was used to investigate if retrograde injection of contrast agent was possible in Thiel embalmed specimens and to verify up to which diameter lymphatic vessels could be reconstructed and rendered in 3D, after CT scanning. 3D renderings were used for digital diameter measurement, to determine the smallest lymphatic diameter that could still be visualized on CT. Finally, the contrast agent concentration was adapted based on the findings during image reconstruction and 3D rendering. All Thiel embalmed specimens proved suitable for retrograde injection of contrast agent into the thoracic duct and all 3D renderings perfectly overlapped with the dissection pictures. The smallest diameter of contrast filled lymphatics that could be reconstructed and rendered in 3D was 0.23 mm. Increasing the concentration of barium sulfate from 10 to 50% reduced the postprocessing time needed to render a "clean" 3D structure, following automatic segmentation based on grey values, by 95%. The authors would recommend the use of Thiel embalmed specimens for mapping the lymphatic system, as these specimens do not show the rapid putrefaction that occurs in fresh frozen specimens, thus greatly facilitating experimental planning.

Call for a Multidisciplinary Effort to Map the Lymphatic System with Advanced Medical Imaging Techniques: A Review of the Literature and Suggestions for Future Anatomical Research

This review intends to rekindle efforts to map the lymphatic system by using a more modern approach, based on medical imaging. The structure, function, and pathologies associated with the lymphatic system are first discussed to highlight the need for more accurately mapping the lymphatic system. Next, the need for an interdisciplinary approach, with a central role for the anatomist, to come up with better maps of the lymphatic system is emphasized. The current approaches on lymphatic system research involving medical imaging will be discussed and suggestions will be made for an all-encompassing effort to thoroughly map the entire lymphatic system. A first-hand account of our integration as anatomists in the radiotherapy department is given as an example of interdisciplinary collaboration. From this account, it will become clear that the interdisciplinary collaboration of anatomists in the clinical disciplines involved in lymphatic system research/treatment still holds great promise in terms of improving clinical regimens that are currently being employed. As such, we hope that our fellow anatomists will join us in an interdisciplinary effort to map the lymphatic system, because this could, in a relatively short timeframe, provide improved treatment options for patients with cancer or lymphatic pathologies all over the world. Anat Rec, 302:1681-1695, 2019. © 2019 American Association for Anatomy.