Intensity-Modulated Radiotherapy For Nasopharyngeal Carcinoma:a Systematic Review

Objective Intensity-modulated radiation therapy (MRT) is an advanced form of three-dimensional conformal radiation therapy (3D-CRT) that uses non-uniform radiation beam intensities to increase the delivery of radiation to the planned treatment volume while minimizing irradiation of normal tissue outside the target. But in some clinical studies, the results of IMRT over conventional radiation therapy (CRT) for nasopharyngeal carcinoma (NPC) have not yet been clarified. Aim to assess the efficacy and safety of IMRT for NPC, randomized controlled trials (RCT) and quasi-randomized control trial were fully retrieved and assessed in this Systematic review.Methods We searched relevant RCTs from CBM(1978-2014.3), VIP(1989-2014.3), CNKI(1994-2014.3), Wanfang(1997-2014.3), Cochrane Library (2014.3), PubMed(1966-2014.3), EMBASE(1974-2014.3). RCTs of IMRT versus CRT for NPC were included. Two researchers evaluated the quality of these included studies and analyzed data by Review Manager5.1software independently.Results24RCTs were included (4in English and20in Chinese),2385patients in all. Meta analysis suggested that:Compared with CRT, IMRT can significantly improve the recent effective rate (RR=1.30,95%CI:1.17-1.46, P＜0.00001). IMRT can also significantly improve1-year overall survival(OS)(RR=1.08,95%CI:1.02-1.15, P=0.007),2-year OS (RR=1.23,95%CI:1.11-1.36, P＜0.0001) and5-year OS(RR=1.19,95%CI:1.08-1.31, P=0.0004), improve1-year local relapse-free survival (LRFS)(RR=1.21,95%CI:1.11-1.32, P＜0.0001) and4-year LRFS (RR=1.25,95%CI:1.01-1.55, P=0.04), significantly improve1-year distant metastasis-free survival (DMFS)(RR=1.06,95%CI:1.00-1.12, P=0.04),2-year DMFS (RR=1.15,95%CI:1.04-1.27, P=0.005). Compared with CRT, IMRT had a higher fractional stimulated whole salivary flow rate and stimulated parotid salivary flow rate.IMRT can also significantly reduce the early xerostomia (RR=0.56,95%CI:0.44-0.72, P＜0.00001), reaction of mucosa (RR=0.83,95%CI:0.73-0.94, P=0.003), reaction of skin (RR=0.54,95%CI:0.41-0.72, P＜0.0001) and xerostomia1year post-RT(RR=0.51,95%CI:0.33-0.77, P=0.001), trismus (RR=0.33,95%CI:0.13-0.87, P=0.02)and temporal lobe neuropathy (RR=0.59,95%CI:0.42-0.85, P=0.004).IMRT has an trend to shorten treatment time, but increase cost.Conclusion Current available evidence demonstrated that compared with CRT, Intensity-modulated Radiotherapy can improve the recent effective rate and long-term survivals rates while reduce the acute and late complications for nasopharyngeal carcinoma. So it was recommended as a chief treatment method for nasopharyngeal carcinoma. How more studies about IMRT is still needed.