Pattern analyses reveal clues to better patient management
Subtle clues to the better management of cancer patients may lie hidden in images otherwise used exclusively for diagnosis. German researchers told colleagues Sept. 23 at the 34th Congress of the European Society for Medical Oncology that ultrasound images of lymph nodes may contain clues to whether and to what extent melanoma has begun to spread. The discovery raises the possibility that ultrasound might help oncologists predict a patient's probable survival without the need for sentinel node biopsy.
"For the first time we have established that ultrasound patterns can be used as criteria for diagnosing disease progression and tumor burden," said Christiane Voit, head of the diagnostic unit at the Skin Cancer Centre at Charit - Universittsmedizin Berlin.
The significance of this finding is hard to overestimate. Discovering whether cancer has spread to the lymph nodes is the most important factor influencing the prognosis and treatment of melanoma patients, according to Voit. Typically one or two sentinel nodes are removed and analyzed to see whether cancer has metastasized. For the vast majority of patients undergoing this procedure, however, sentinel node biopsy is unnecessary, as the tissues show evidence of cancer spread in only 20% of patients. All who have sentinel node biopsy, however, are at risk of adverse effects from the surgery, including chronic swelling and seroma. Using ultrasound first to detect the presence of sentinel node metastases could be a noninvasive way of limiting the number of patients who require surgery. It could also serve as a watchful follow-up, she said.
Two ultrasound patterns allowed Voit and colleagues to determine the presence of tumor cells in sentinel lymph nodes. The presence of these patterns indicated cancer spread in 75% to 90% of cases.
One, a balloon-shaped ultrasound pattern, indicated a large amount of cancer in the sentinel node. "This ultrasound pattern was a late sign, occurring only in cases of advanced metastasis," Voit said.
The second, a pattern of peripheral perfusion, where small blood vessels start to surround the lymph node, indicated that a small number of cancer cells were present in the node.
Correctly interpreting the two ultrasound patterns also leads to accurate predictions of patient survival, she said. The researchers found that 93% of patients with neither pattern, 87% of those with peripheral perfusion, and 56% of those with balloon-shaped ultrasound patterns survived for at least five years.
The research still needs to be confirmed in multicenter, randomized clinical trials, Voit said, but if the results pan out, this unconventional interpretation of ultrasound scans might spare future melanoma patients unnecessary surgery to remove sentinel nodes, she said.