Lymphatic mapping in esophageal cancer surgery

Lymphatic spread strongly influences the staging and treatment of oesophageal cancer. Tumour cells may travel beyond the primary lesion through a network that crosses the chest and abdomen, making the pattern of nodal involvement clinically important during oesophagectomy.

Lymphatic mapping uses tracers, imaging, or fluorescence techniques to show drainage pathways and potentially identify sentinel lymph nodes. The approach is intended to support a more precise lymphadenectomy, guide pathology, and improve understanding of how individual tumours spread.

This subject received attention at the 17th World Congress for Esophageal Diseases, hosted virtually by the International Society for Diseases of the Esophagus from 27–30 September 2021. Scientific sessions, workshops and research abstracts examined developments relevant to surgeons, gastroenterologists, oncologists and specialist nurses.

For Australian clinicians, the issue is particularly relevant to multidisciplinary services in Sydney, Melbourne, Brisbane, Adelaide and Perth. Patients may move between metropolitan cancer centres and regional hospitals, so a mapping strategy must fit local imaging, operating theatre, pathology and Medicare-funded care pathways.

Why lymphatic drainage matters

The oesophagus has an extensive longitudinal lymphatic system. A lesion in the upper, middle or lower third can drain to different nodal stations, and tumour cells may bypass the nearest apparent node. This makes a limited, location-based dissection potentially unreliable when used without full staging information.

Standard treatment often combines neoadjuvant chemotherapy or chemoradiotherapy with surgery for locally advanced disease. The operation may include transthoracic or transhiatal oesophagectomy and a two-field lymphadenectomy. The appropriate extent depends on tumour location, histology, response to treatment, patient fitness and the expertise of the treating centre.

Mapping can add a visual or anatomical layer to this decision-making. It does not currently replace careful nodal dissection or comprehensive histopathological examination, but it may help researchers and surgeons identify unexpected drainage routes and refine operative planning.

Techniques used to trace tumour drainage

Several methods have been investigated. A tracer can be injected around the tumour during endoscopy, allowing surgeons to follow its route to regional lymph nodes. Radiocolloid mapping may be combined with lymphoscintigraphy, while blue dyes can provide direct visual evidence during surgery.

Near-infrared fluorescence with indocyanine green is increasingly studied because it can display lymphatic channels in real time. The technology may help identify nodes that are difficult to see through normal tissue, although visibility varies with injection technique, tissue depth, equipment and the effects of prior treatment.

Common mapping approaches include:

• Indocyanine green fluorescence during minimally invasive or robotic surgery
• Radiocolloid injection with preoperative lymphoscintigraphy
• Blue dye or carbon-based tracers for visual node localisation
• Sentinel lymph node sampling linked to detailed pathology

Where mapping may influence surgery

The main potential benefit is improved identification of lymph nodes at risk of harbouring micrometastatic disease. If a sentinel node contains tumour, this finding may reinforce the need for broader nodal clearance or additional treatment. If it is negative, the result could eventually support more selective surgery in carefully chosen patients.

That possibility remains under investigation in oesophageal cancer. Neoadjuvant therapy can alter lymphatic channels and reduce the reliability of sentinel node techniques. Tumour regression, fibrosis and multifocal drainage can produce false-negative results, so a negative mapped node cannot automatically exclude disease elsewhere.

Mapping may also contribute to safer dissection. Clearer recognition of lymphatic pathways could support research into reducing unnecessary tissue trauma, although the procedure still carries the established risks of oesophagectomy, including anastomotic leak, pulmonary complications, chyle leak and recurrent laryngeal nerve injury.

Applying the evidence in Australia

Australian practice is shaped by centralised high-volume surgery, multidisciplinary tumour boards and access to specialist pathology. A patient in regional New South Wales or Queensland may have imaging locally but travel to Sydney or Brisbane for surgery, while follow-up and systemic treatment may return to a regional service. Consistent documentation is therefore essential.

The technique selected should match the resources of the hospital and the experience of the surgical team. Fluorescence-capable laparoscopic or robotic systems are available in some Australian centres, but access is not uniform. The cost of tracers, theatre time, nuclear medicine support and pathology processing should be considered alongside the expected clinical value.

Important implementation points include:

• Confirming the injection protocol and timing before the operation
• Recording mapped nodes separately for the pathology team
• Correlating fluorescence or radiotracer findings with preoperative imaging
• Discussing uncertain evidence within the multidisciplinary meeting

From research findings to patient care

The most useful role for lymphatic mapping at present may be as an adjunct to established staging and surgery. It can generate detailed anatomical information, help standardise research protocols and reveal patterns that are difficult to appreciate through conventional imaging alone.

Future studies need to clarify whether mapping improves recurrence outcomes, reduces morbidity or safely permits a less extensive operation in selected patients. Australian research networks and specialist centres can contribute valuable data by recording tracer choice, injection site, nodal yield, treatment response and long-term follow-up in a consistent format.

For a patient being assessed for oesophageal cancer surgery, the practical next step is to have the proposed mapping method, lymphadenectomy extent and pathology plan documented at the multidisciplinary tumour board before the operation.