Biopsy-Free Detection of Melanoma Metastasis

According to the results of a new study, a new imaging technique is able to detect the distant spread of melanoma to the lymph nodes, which could help patients avoid potentially risk surgery. Researchers tested the non-invasive technique in a first-in-human study as a potential alternative to standard lymph node surgery.

The results, from researchers at the University Hospital Essen and the University of Duisburg-Essen in Germany, are published in Science Translational Medicine.

The novel audio-visual approach used to image patients with melanoma both ex vivo and in vivo significantly improved the tumor metastasis detection rate in excised sentinel lymph nodes compared with standard protocols (22.9% vs 14.2%).

For patients diagnosed with melanoma, cancer guidelines recommend a sentinel lymph node excision to assess the presence of microscopic metastatic disease. Yet in most patients, the surgery does not find evidence of cancer spread and exposes patients to potential complications and adverse effects from surgery.

Joachim Klode, MD, of the department of dermatology, venerology, and allergology at the University Hospital Essen and the University of Duisburg-Essen in Germany, and colleagues used a non-radioactive approach known as multispectral optoacoustic tomography (MSOT) that is able to visualize melanin, the pigment produced by melanocytes and melanoma cells. A fluorescent green dye, rather than radioactive material was used to visualize the lymph nodes. Then, a handheld MSOT detector pulses light through the skin and into the lymph nodes to generate an ultrasound signal. If no melanin is detected in the lymph nodes, the patient is metastasis free.

The researchers first tested the approach on more than 500 lymph nodes removed from 214 melanoma patients. The technique was reliable and performed better compared to current diagnostic approaches, according to the researchers.

The combined MSOT and lymph node detection using a fluorophore reliably visualized the sentinel lymph node in 20 patients, with up to a 5 cm penetration, and was better able to detect metastasis compared to biopsy visualization using radioactive imaging.

This initial study resulted in no false negatives, that is, no patients were found metastasis-free using the technique when, in fact, they had melanoma spread.

This visualization technique may also be used to detect lymph node metastasis in patients with other tumor types, according to the study authors.

“If validated in larger studies, this approach could alleviate the need for invasive sentinel lymph node excision surgery in a significant number of patients,” concluded the study authors.