Safe and less invasive search for metastases

Malignant melanoma is the most dangerous form of skin cancer. Every year more than 220,000 new cases are identified worldwide, and the annual incidence is climbing. The earlier one can make the diagnosis, the better the chances for a complete cure. If the tumor has already formed metastases, the prognosis for the patient becomes significantly worse. Since the tumor metastases spread primarily via the lymphatic system, one usually first assesses the lymph nodes closest to the primary tumor.

Typically, surgery would then follow to resect the lymph nodes. Thanks to the new imaging procedure established by Dr. Joachim Klode and Dr. Ingo Stoffels, surgery will not be necessary for many patients in the future.

Via a technology called “Multispectral Optoacoustic Tomography”, which has been developed by the German company iThera Medical, cancer cells in the lymph nodes closest to the primary tumor can be detected safely and less invasively.

First, the lymph nodes that should be diagnosed need to be identified. In contrary to today’s procedure, this no longer requires a radioactive tracer, but a dye called indocyanine green. Its drainage via the lymphatic vessels marks the sentinel lymph node. After identification, the lymph node would normally be surgically resected and assessed in the pathology. The patient needs to be hospitalized for several days for this procedure.

With optoacoustic technology, a pulsed laser illuminates the tissue through the skin. The light energy absorbed in the tissue generates an ultrasound signal which is acquired by a highly sensitive ultrasound detector.

Once the lymph node for diagnosis has been identified through detection of the injected dye, the images acquired at multiple wavelengths reveal the presence of melanin in the tissue. Melanin is a clear indicator for a possible metastasis. In the absence of such a signal, the patient can be given the all-clear. The patient then does not require a surgery.

In nearly half of the patients diagnosed with the new MSOT procedure, a metastasis could be ruled out. The usual surgical procedure with its burden on the patient would have been unnecessary in these cases. The results of this study are reported in the current edition of the scientific journal Science Translational Magazine.

The Skin Clinic is part of the West German Tumor Center (WTZ) at the University Hospital Essen. It is the country’s largest of its kind and has been awarded as oncologic excellence center. Oncology is an emphasis of the clinic, as is research and teaching at the University Hospital Essen and the Medical Faculty of the University Duisburg-Essen.

Further information: Christine Harrell, Tel. +49 (0)201 723-1615, christine.harrell@uk-essen.de

http://stm.sciencemag.org/content/7/317/317ra199.full