Removing lymph nodes during cancer surgery has saved countless lives in many tumour types. Yet recent research is challenging parts of this long-standing practice.

Imagine your body's immune defences as a city, and lymph nodes as the hubs where police and firefighters gather fresh intel to launch their attack on criminals. What happens if you remove too many of these hubs? This is a new question at the centre of modern cancer surgery.

When surgeons remove lymph nodes, it's usually for two reasons: to find out whether cancer has spread, and to prevent further spread to other organs. For decades, this approach represented the best standard of care.

If a tumour escapes its original site, cancer cells often travel through lymph vessels and settle in the nearest lymph nodes, which act as

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