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Introduction: Monocarboxylate transporter 4 (MCT4) is a cell membrane transporter of lactate. MCT4 is a tumor-specific marker of oxidative stress, glycolysis and hypoxia in tumor stromal cells. We investigated HPV positive and negative tumors with regional metastases to cervical lymph nodes (LN) to study how the metastatic tumor cells interact with their microenvironment. By selecting cancers with extracapsular extension (ECE), we intended to evaluate the interaction between metastases and the surrounding extranodal tissue.


Clinical data were collected from 24 advanced stage oropharyngeal squamous cell carcinoma (OPSCC) patients with neck LN metastasis. All patients presented with at least N1 disease and had ECE. Sixteen cases were negative for HPV and eight were positive. Ten patients (42%) had ECE < 1 mm, and 14 (58%) had ECE > than 1 mm. The extent of ECE was quantified on H&E stains by distance from the edge of capsule. The paraffin-embedded metastatic LN sections were stained with MCT4 and quantification was accomplished using the Aperio Co-localization algorithm.


High stromal MCT4 expression was strongly associated with the extent of ECE regardless of HPV status (p=0.031). The stromal MCT4 expression in ECE area was significantly higher as opposed to the surrounding extranodal tissue adjacent to intact capsule (p<0.001). We also found a borderline difference in expression of MCT4 in HPV- LN with ECE >1mm vs. <1mm(p=0.06).


MCT4 is a marker of oxidative stress and higher expression of stromal MCT4 in ECE area is significantly correlated with the extent of ECE. The stromal cells separating nests of cancer cells in ECE area have apparent expression of the MCT4. Together these findings provide new insight into the critical role of stromal MCT4 in nodal metastasis and ECE in OPSCC and it may be useful to develop a novel prognostic marker and new anti-cancer agents.