Impact of prior neck irradiation on surgical management of tongue cancer after nasopharyngeal carcinoma: A single-center retrospective study

Secondary malignancies pose a significant challenge for individuals with a history of nasopharyngeal carcinoma (NPC), a prevalent head and neck cancer among the Chinese population. Despite advancements in radiation techniques leading to improved locoregional control and overall survival, survivors of NPC face a higher risk of developing secondary cancers compared to the general population. Squamous cell carcinoma of the oral tongue is a common secondary malignancy among NPC survivors, adding to their burden. Surgery remains the cornerstone of treatment, and prophylactic neck dissection is recommended for patients with clinically node-negative disease due to the high rate of occult nodal metastasis. However, neck dissection in previously irradiated necks is associated with increased complications. This study aims to evaluate the efficacy of prophylactic neck dissection in NPC survivors, focusing on occult nodal metastasis rates and survival outcomes, in a 15-year retrospective cohort from the Department of Otorhinolaryngology of a tertiary referral center in Hong Kong. 262 tongue cancer patients treated surgically, including 33 NPC survivors, were included in the study. NPC survivors with secondary tongue cancers had significantly lower rates of occult nodal metastasis than patients with primary tongue cancer (5.3% vs. 25.6%, p = 0.049). No statistically significant survival benefit from prophylactic neck dissection was observed in the NPC survival group. This study highlighted a potentially important clinical observation -- NPC survivors with secondary tongue cancer appear to have a lower rate of occult nodal metastasis and no clear survival advantage from prophylactic neck dissection, compared with patients with primary tongue cancer. These findings suggest that routine prophylactic neck dissection may be unnecessary in this subgroup. However, they should be interpreted as hypothesis-generating and require confirmation in larger, multi-center cohorts to clarify the distinct clinical behavior of these patients and to optimize neck management strategies.