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

Abstract

Introduction

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.

Conclusion

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

Introduction

Oral cavity cancer is currently a globally prominent malignancy. According to the Global Burden of Disease database, more than 300,000 patients had lip and oral cavity cancer worldwide in 2017 [1].

The oral cavity is a sophisticated anatomical structure, comprising the buccal mucosa, gingiva, hard palate, floor of mouth, tongue and retromolar region. The mortality rates for oral cavity cancer in these various parts differ [2]. Oral cavity cancer risk factors are smoking, betel nut chewing and alcohol consumption [3,4].

The 5-year overall survival rate is approximately 50% for patients with oral cavity cancer [2,5]. Due to advances in medical technology [6,7], patients with the cancer live longer than previously. Subsequently, quality of life has become increasingly prominent concern.

According to National Comprehensive Cancer Network (NCCN) guideline, the standard oral cavity cancer treatment is operation or surgical resection. When adverse pathological features exist in oral cavity cancer, including in the positive or close margin and the extracapsular nodal extension, adjuvant concurrent chemoradiation should be administered. In patients with other risk factors, including pathological stage T3 or T4 disease, N2 disease, perineural invasion, and lymphovascular invasion, adjuvant radiotherapy should be delivered [8].

The appropriateness of contralateral neck irradiation in the adjuvant setting of oral cavity cancer is a prominent question in clinical settings. Reportedly, the omission of contralateral neck irradiation better preserves the contralateral parotid gland and reduces xerostomia [9]. The basic principle of radiotherapy is to reduce irradiation volume without compromising locoregional control.

There is some research on this topic. However, after literature review, no systematic review or meta-analysis have been performed. Considering the heterogeneous setting of these studies, a systemic approach is required to obtain conclusive results. As the result, our study aimed to identify the patient groups of oral cavity cancers who were candidate of elective contralateral neck irradiation.