Julie A. Sosa, MD
A new study by Duke cancer researchers is providing the first-ever guidance for physicians and patients on what constitutes an adequate lymph node dissection, especially in cases of intermediate-risk papillary thyroid cancer (PTC).
Cancer of the thyroid (a gland located at the base of the neck that produces hormones that regulate metabolism) is the fastest increasing cancer in the U.S. in both men and women, though it’s three times as common in women. The incidence has increased nearly 300 percent in 30 years, partly due to improved detection methods.
About half of patients with PTC, the most common kind of thyroid cancer, will have metastatic disease to lymph nodes near the thyroid gland at diagnosis, say researchers.
“It’s a common cancer and it’s becoming more common, and we are still not improving survival,” said one of the study authors Julie A. Sosa, MD, who leads the Endocrine Neoplasia Diseases Group at the Duke Cancer Institute (DCI) and Duke Clinical Research Institute (DCRI) “This study has potentially profound implications for who should be doing thyroid cancer surgery, and affects how we counsel patients about risk of recurrence and prognosis and how we decide about the need for adjuvant treatment after surgery.”
The study brought together the collaborative work of researchers from the Duke University departments of surgery, radiation oncology, biostatistics and bioinformatics, medicine, and the DCI and DCRI. The retrospective study was published Monday, Aug. 15, in the Journal of Clinical Oncology.
The surgical management of intermediate-risk disease is controversial. Experts still do not fully agree whether surgery should be restricted to removing the thyroid gland alone or to take out nearby lymph nodes as well. If lymph nodes are removed, how many should be taken out? Do the potential benefits outweigh the risks? When does it provide survival advantage?
Studies show that most intermediate-risk PTC patients have between one and three lymph nodes removed, which might not be enough to determine if there is in fact metastatic disease.
“Decisions are being made on only a couple of nodes, a lot of the time, in the data that we saw,” said the study’s senior author Terry Hyslop, PhD, director of DCI Biostatistics, explaining that a physician shouldn’t assume, with such a small sample, that the patient doesn’t have occult disease.
In the study, researchers looked at the number of negative (disease-free) lymph nodes removed from the neck, and using a formula that included patient demographic, clinical and pathologic factors, anticipated the likelihood that a positive (metastatic) lymph node was left behind.