Patients were randomly assigned ( 1:1 ) by use of a central interactive voice response system using a block randomisation schedule ( block size four ) stratified by hormone receptor status , first-line progression-free survival , selected chemotherapy , and lactate dehydrogenase concentration , to receive second-line single-agent chemotherapy either alone or with bevacizumab ( 15 mg/kg every 3 weeks or 10 mg/kg every 2 weeks ) .