***TASK***
the task is to simplify the input abstract of a biomedical literature

***INPUT***
the input is the abstract of a biomedical literature

***OUTPUT***
the output is the simplified abstract for the input abstract of a biomedical literature

***DOCUMENTATION***

***EXAMPLES***

Input: Nineteen randomised studies (2728 participants) of concurrent chemoradiotherapy versus radiotherapy alone were included. Chemoradiotherapy significantly reduced overall risk of death (HR 0.71, 95% CI 0.64 to 0.80; I2 0%; 1607 participants) and overall progression-free survival at any site (HR 0.69, 95% CI 0.58 to 0.81; I2 45%; 1145 participants). Incidence of acute oesophagitis, neutropenia and anaemia were significantly increased with concurrent chemoradiation.  Six trials (1024 patients) of concurrent versus sequential chemoradiation were included. A significant benefit of concurrent treatment was shown in overall survival (HR 0.74, 95% CI 0.62 to 0.89; I2 0%; 702 participants). This represented a 10% absolute survival benefit at 2 years. More treatment-related deaths (4% vs 2%) were reported in the concurrent arm without statistical significance (RR 2.02, 95% CI 0.90 to 4.52; I2 0%; 950 participants). There was increased severe oesophagitis with concurrent treatment (RR 4.96, 95%CI 2.17 to 11.37; I2 66%; 947 participants). This update of the review published in 2004 incorporates additional trials and more mature data. It demonstrates the benefit of concurrent chemoradiation over radiotherapy alone or sequential chemoradiotherapy. Patient selection is an important consideration in view of the added toxicity of concurrent treatment. Uncertainty remains as to how far this is purely due to a radiosensitising effect and whether similar benefits could be achieved by using modern radiotherapy techniques and more dose intensive accelerated and/ or hyperfractionated radiotherapy regimens.
Output:

A total of twenty-five randomised studies (including 3752 patients) were included in this updated review: nineteen trials (2728 patients) comparing concurrent chemoradiotherapy with radiotherapy alone and six trials (1024 patients) comparing concurrent with sequential chemoradiotherapy. Both comparisons demonstrated significant reduction in risk of death with use of concurrent chemoradiation, with an associated increase in incidence of acute oesophagitis.