Supplementary Material for: Neck node squamous cell metastasis from unknown primary and mutagen sensitivity: A case series

Most of the neck node metastasis from cancer of unknown primary (CUP) are squamous cell carcinomas (SCCs). The majority of which are human papillomavirus (HPV)-related, frequently show cystic morphology referring to Waldeyer’s ring origin. Here we report four neck node SCCs metastases from CUP. In our institute between 1996 and 2006, 432 patients with head and neck (HN) SCC underwent pretreatment mutagen sensitivity (MS) assay. Four of them with age ≤50 years had metastatic cervical nodes (CNs) from CUP. Primary treatment was CN dissection ± radiotherapy. All patients had elevated (>1.0 chromatid break/cell) MS. The man died of progressive neck metastasis within 3 years and the three women still alive more than 15 years after initial treatment of HPV+ (two) or cystic (one) SCC. Two women developed second and third distant site metachronous primary cancers. HPV+ or cystic HNSCC from CUP with elevated MS indicates good outcome. Distant site metachronous cancers of different histologic origin cannot be explained by field cancerization. The clinical significance of elevated MS in neck node SCC metastasis from CUP needs further investigation.