***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The incidence of brain metastases secondary to small cell lung cancer ( SCLC ) is about 35 % and the treatment strategy of brain irradiation with respect to dose and fractionation is controversial . In order to evaluate treatment outcome of brain irradiation in SCLC patients with brain relapse , we retrospectively evaluated all patients treated with brain irradiation in the eastern part of Denmark from 1988 to 1992 ( PCI patients excluded ) . During this 5-year period , 101 evaluable patients were included ( 44 females , 57 males ) ( median age 61 years ; range , 39 - 75 years ) . Forty-four patients , of whom 43 were in extracerebral complete remission ( CR ) , received  extended course ( EC ) brain irradiation  ( > 45 Gy , treatment schedule > 4 weeks ) . Fifty-seven patients received short course ( SC ) brain irradiation ( < 30 Gy , treatment schedule < 1 week ) . Among the SC treated patients , 14 were in CR , 20 had partial remission or stable disease and 23 had progressive extracerebral disease . The median survival ( from diagnosis of brain metastases ) in the group receiving irradiation with EC ( 44 patients ) was 160 days ( range , 74 - 2021 days ) , while the 57 patients treated with SC had a median survival of 88 days ( range , 20 - 948 days ) ( P = 0.00001 , Log-Rank analysis ) . In a subgroup of 14 patients in extracerebral CR , receiving SC irradiation , the median survival was 83 days ( range , 15 - 948 days ) . When the latter patients were compared to the 43 patients in CR in the group treated with EC , a statistically significant difference was shown ( P = 0.034 , Log-Rank analysis ) . Using Cox-hazard regression analysis with backward elimination , liver metastases and poor performance status were adverse prognostic signs , although the only significant parameters of survival were gender ( female vs. male , relative risk of dying 1 and 1.52 , P = 0.05 ) and schedule of brain irradiation ( extended course vs. short course , relative risk of dying , 0.36 and 1 , P < 0.001 ) . Extended course irradiation of brain relapse secondary to SCLC seems in general to be of limited value , although a significant prolonged survival at approximately 7 weeks , was obtained . The prolongation of survival does not seem worthwhile considering the length of treatment time ( 5 - 6 weeks ) compared to SC treatment ( 1 week ) . However , the data do not permit evaluation of the quality of life of the patients . This retrospective evaluation suggests the need for r and omized trials with carefully planned quality -of-life assessment 
    Output:
    
From the limited evidence available , survival appeared to increase when patients were selected by performance status ( survival increasing from approximately three to seven months in high performance status groups , as defined by Karnofsky performance status or Recursive Partitioning Analysis classification ) .
The evidence suggests no survival benefit when patients with poor performance status were treated with whole brain radiotherapy .
WBRT appears to be of benefit in higher performance status patients but not in low performance status patients .