Ultrasound-guided biopsy: Procedure highly sensitive for melanoma metastasis detection

March 1, 2009

A new ultrasound-guided fine needle aspiration cytology technique used to extract cells from suspected melanoma-infiltrated sentinel lymph nodes offers a more sophisticated and very accurate clinical assessment of sentinel lymph nodes.

Key Points

Berlin - Sentinel lymph node dissection and biopsy has become common practice, as it is deemed necessary by many clinicians to rule out the spread of melanoma.

However, a novel sophisticated ultrasound-guided fine-needle aspiration cytology (US-FNAC) technique proves to be extremely accurate in ruling out metastatic melanoma spread to sentinel lymph nodes (SL), and can potentially spare melanoma patients from unnecessary sentinel lymph node biopsy (SLNB) surgeries.

"The US-FNAC procedure is much less invasive than traditional SLNB, and because of its extreme accuracy, melanoma patients now should not have to undergo SLNBs to assess their tumor status," says Christiane A. Voit, M.D., head of the diagnostic unit at the Skin Cancer Center, department of dermatology, Charité Hospital, Humboldt University, Berlin.

Dr. Voit headed a study conducted through the European Organization for Research and Treatment of Cancer (EORTC) melanoma group in which the value of tyrosinase reverse-transcriptase polymerase chain reaction (RT-PCR) of aspirates obtained by US-FNAC of sentinel nodes in patients with melanoma before SLNB and the value of RT-PCR of blood samples of all SLNB patients were compared.

Fine-needle aspiration cytology was performed in sentinel nodes of all patients before and after SLNB. Average follow-up was 28 months.

In the study, which included 590 melanoma patients, US-FNAC could identify 51 of 79 (65 percent) sentinel node metastases.

Overall, Dr. Voit says 65 percent of the samples were determined by the ultrasound system, but specificity reached 99 percent. The positive predictive value was 93 percent; the negative predictive value was 92 percent.

"On the downside, the US-FNAC technique could not correctly identify 7 percent of cases in the sentinel node-negative population; however, because the survival curves for the US-FNAC technique are similar to those for sentinel node surgery, 7 percent can be acceptable," Dr. Voit tells Dermatology Times.

Benefits

Statistics show that approximately 20 percent of patients who undergo sentinel node surgery actually have metastasis to those dissected nodes, effectively making 80 percent of sentinel lymph node dissection procedures superfluous.

"Melanoma patients can greatly benefit from the US-FNAC technique, as it can greatly reduce unnecessary surgeries," Dr. Voit says.

The US-FNAC technique is already being successfully used to assess the status of the sentinel lymph nodes in breast cancer.

Disclosures: Dr. Voit reports no relevant financial interests.