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Characteristics of mucinous adenocarcinoma highlighted



– Head and neck mucinous adenocarcinoma is commonly diagnosed at a low tumor stage with no nodal involvement but with the potential for distant metastases.

The findings come from the largest study of its kind to date, which was presented by Neel R. Sangal at the Triological Society’s Combined Sections Meeting.

“Mucinous carcinoma was previously classified as colloid carcinoma, which leads to increased confusion in the nomenclature,” said Mr. Sangal, a 4th-year student at New Jersey Medical School, Newark.

“This changed in the 1980s, which led to difficulty in characterizing the disease over time. This histology is well studied in the GI system, in the lungs, and in the breast, but the head and neck presentation is extremely rare, and it lacks comprehensive study.

“It commonly presents as a slow-growing, painless, nonulcerated nodule. From case reports, it’s typically low-grade and indolent, but it commonly recurs, and it does have metastatic potential,” he said. “Histologically, it’s characterized by nets of aggressive epithelial cells that are accompanied by significant extracellular mucin.”

In an effort to understand the demographic, clinicopathologic, treatment, and survival characteristics of mucinous adenocarcinoma, the researchers evaluated cases from the Surveillance, Epidemiology, and End Results Program (SEER) database between 1973 and 2014. They selected patients based on their International Classification of Diseases morphological code specific for mucinous adenocarcinoma and ICD primary site code consistent for cancers of the head and neck.

In all, 583 cases met criteria, “which highlights how rare this disease is,” Mr. Sangal said at the meeting, which was jointly sponsored by the Triological Society and the American College of Surgeons.

The mean age at diagnosis was 64.8 years; 55.2% of cases were male, 64.5% were white, 15.4% were black, 8.7% were Hispanic, 6.7% were Asian, and the remaining 5% were from other ethnicities. The four most frequent primary sites were the eyelid (29.8%), followed by skin of the face (22.6%), skin of the scalp and neck (12.2%), and the parotid gland (8.7%). Most of the lesions lacked nodal involvement and metastasis (94.1% and 96.2%, respectively). Histology presented mainly at lower stages. Specifically, 68% had T0-1 disease, 21.5% had T2-3 disease, and 10.5% had T4 disease.

When the researchers stratified treatment frequency by various clinical pathologic characteristics, they found large differences in the type of treatment received by the primary site. “Those on the salivary gland tended to receive radiation at a much higher percentage than those of the skin, which mostly received surgery alone,” Mr. Sangal said. “We also found a linear correlation between T stage and increased use of radiation alongside surgery. Similarly, those with nodal involvement and distant metastasis had increased rates of radiation with surgery.”

Disease-specific survival and overall survival rates were 92.2% and 80.5%, respectively. Advanced age at diagnosis was a significant predictor of survival. In addition, Hispanics had the highest rates of survival, while the white and black patients had similar survival curves. “Tumors of the parotid gland had significantly worse survival outcomes than those of the skin,” Mr. Sangal added. “We also found a linear correlation between T stage and survival. Similarly, those with nodal involvement and distant metastasis also had decreased survival.”

He acknowledged certain limitations of the study, including the potential for inconsistent coding in the SEER database.

Samer T. Elsamna was lead author on the study. None of the researchers reported having financial disclosures.

SOURCE: Elsamna ST et al. Triological CSM 2019, Abstracts.

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