Adjuvant contralateral neck irradiation for oral cavity cancer - A systematic review and meta-analysis

Whether contralateral neck irradiation should be administered for oral cavity cancer is a critical question because patients receiving bilateral neck irradiation experience more adverse effects. Patients not receiving contralateral neck irradiation are at risk of contralateral neck recurrence of oral cavity cancer MATERIALS AND METHODS: Meta-analysis and subgroup analysis were performed for the rates of contralateral neck recurrence of oral cavity cancer in patients receiving no contralateral neck radiation. We aimed to identify the patient group suitable for contralateral neck radiotherapy omission. The PRISMA guideline was used for this study. We extracted data including the first author, country, sample size, numbers of patients receiving ipsilateral neck radiotherapy and experiencing contralateral neck recurrence, participant characteristics, and details of cancer types RESULTS: The rate of contralateral neck recurrence is extremely low, 3.4% (95% confidence interval: 2.2%-5.4%). Isolated contralateral neck recurrence occurred in 18 of 524 patients receiving radiotherapy to the primary tumor site with or without ipsilateral irradiation. The subgroup analysis was conducted to investigate pathological lymph node stage and subsite. Subgroup analysis showed that the N2-3 group was more likely to exhibit recurrence in contralateral neck than the N0-1 group was (14.4% versus 1.5%, p = 0.0008). In addition, the contralateral neck recurrence rate was 6.3% (95% CI = 2.3%-13.1%) and 2.8% (95% CI = 1.5%-4.8%), in the tongue cancer patient group and the non-tongue cancer patient group, respectively. Meta-regression showed that the rate of contralateral recurrence was not different between both groups (p = 0.08). Only 2 exhibited isolated contralateral neck recurrence (5.1%) in pN0-1 tongue cancer patient. Most of them (>90%) are lateralized.

In conclusion, the omission of contralateral irradiation is reasonable in pN0-1, well lateralized oral cavity cancer.