Adding Concomitant Chemotherapy to Postoperative Radiotherapy in Oral Cavity Carcinoma with Minor Risk Factors: Systematic Review of the Literature and Meta-Analysis

SIMPLE SUMMARY: Oral cavity carcinoma (OCC) is the 11th most frequently diagnosed cancer; despite a multimodal treatment, locally advanced OCC, managed by surgery and adjuvant therapies, remains at high risk of recurrence, with a 5-year overall survival (OS) of 51%. The efficacy of postoperative chemotherapy in addition to radiotherapy (POCRT) in low–intermediate risk OCC is a controversial matter in the absence of high-risk features (ENE, R1). To establish the role of POCRT in a population with solely minor risk factors (perineural invasion or lymph vascular invasion; pN1 single; DOI ≥ 5 mm; close margin; node-positive level IV or V; pT3 or pT4; multiple lymph nodes without ENE), we performed a systematic review and meta-analyses focused on OS, disease-free survival (DFS), and local-recurrence-free survival (LRFS). Thirteen studies met the inclusion criteria and were included in the quantitative meta-analyses. Our preliminary results are in favor of POCRT in terms of OS but not conclusive for DFS and LRFS. Further analyses are suggested. ABSTRACT: When presenting with major pathological risk factors, adjuvant radio-chemotherapy for oral cavity cancers (OCC) is recommended, but the addition of chemotherapy to radiotherapy (POCRT) when only minor pathological risk factors are present is controversial. A systematic review following the PICO-PRISMA methodology (PROSPERO registration ID: CRD42021267498) was conducted using the PubMed, Embase, and Cochrane libraries. Studies assessing outcomes of POCRT in patients with solely minor risk factors (perineural invasion or lymph vascular invasion; pN1 single; DOI ≥ 5 mm; close margin < 2–5 mm; node-positive level IV or V; pT3 or pT4; multiple lymph nodes without ENE) were evaluated. A meta-analysis technique with a single-arm study was performed. Radiotherapy was combined with chemotherapy in all studies. One study only included patients treated with POCRT. In the other 12 studies, patients were treated with only PORT (12,883 patients) and with POCRT (10,663 patients). Among the patients treated with POCRT, the pooled 3 year OS rate was 72.9% (95%CI: 65.5–79.2%); the pooled 3 year DFS was 70.9% (95%CI: 48.8–86.2%); and the pooled LRFS was 69.8% (95%CI: 46.1–86.1%). Results are in favor of POCRT in terms of OS but not significant for DFS and LRFS, probably due to the heterogeneity of the included studies and a combination of different prognostic factors.