Gemcitabine-Based Chemoradiation in the Treatment of Locally Advanced Head and Neck Cancer: Systematic Review of Literature and Meta-Analysis

Background. Platinum-based concurrent chemoradiation (CCRT) improves locoregional control and overall survival of locoregionally advanced (LA) squamous cell carcinoma of the head and neck (SCCHN) when compared to radiotherapy alone, but this approach is hampered by significant toxicity. Therefore, alternative ways to enhance the radiation effects are worth investigating. Gemcitabine (2',2'-difluorodeoxycytidine), in addition to its activity against a variety of solid tumors, including SCCHN, is one of the most potent radiosensitizers, and it has an overall favorable safety profile. In this paper, the clinical experience with gemcita bine-based chemoradiation in the treatment of patients with LA-SCCHN is reviewed. Methods. We conducted a review of the literature on the clinical experience with radiotherapy combined with either single-agent gemcitabine or gemcitabine/cisplatin-based polychemotherapy for the treatment of patients with LA-SCCHN. We also searched abstracts in databases of major international oncology meetings from the last 20 years. A meta-analysis was performed to calculate pooled proportions with 95% confidence intervals (Os) for complete response rate and grade 3-4 acute mucositis rate. Results. A total of 13 papers were eligible for the literature review. For schedules using a gemcitabine dose intensity (DI) below 50 mg/m2 per week, the complete response rate was 86% (95% CI, 74%-93%) with grade 3-4 acute mucositis rate of 38% (95% CI, 27%-50%) and acceptable late toxicity. In one of the studies employing such low Dls, survival data were provided showing a 3-year overall survival of 50%. Compared with DI 50 mg/m2 per week, there was no difference in the complete response rate (71%; 95% Cl, 55%-83%; p =.087) but a significantly higher (p <.001) grade 3-4 acute mucositis rate of 74% (95% Cl, 62V0-83%), often leading to treatment interruptions (survival data provided in 8 studies; 3-year overall survival, 27%-63%). Late toxicity comprising mainly dysphagia was generally underreported, whereas information about xerostomia and skin fibrosis was scarce. Conclusion. This review highlights the radiosensitizing potential of gemcitabine and suggests that even very low dosages (less than 50 mg/m2 per week) provide a sufficient therapeutic ratio and therefore should befurther investigated. Refinements in radiation schemes, including intensity-modulated radiation therapy, in combination with low-dose gemcitabine and targeted agents, such as cetuximab, are currently being investigated.