789
Severe C. difficile colitis occurred in 2 patients (6.1%) after receiving cisplatin-based combination chemotherapy for ovarian malignancies.
 ( adverse event: occurred ,  2 patients (6.1%): Subject, 2: Subject.Population, (6.1%): Subject.Population, Severe C. difficile colitis: Effect, cisplatin-based combination chemotherapy: Treatment, cisplatin: Treatment.Drug, ovarian malignancies: Treatment.Disorder, chemotherapy: Treatment.Route) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: adverse event,potential therapeutic event, Arguments type: Treatment.Disorder,Treatment.Time_elapsed,Treatment.Dosage,Subject.Race,Treatment.Drug,Treatment.Route,Subject.Disorder,Treatment.Freq,Treatment,Effect,Subject.Population,Treatment.Duration,Combination.Drug,Subject,Subject.Age,Subject.Gender. 
Text: {0} 
Answer:
 ( adverse event: occurred ,  2 patients (6.1%): Subject, 2: Subject.Population, (6.1%): Subject.Population, Severe C. difficile colitis: Effect, cisplatin-based combination chemotherapy: Treatment, cisplatin: Treatment.Drug, ovarian malignancies: Treatment.Disorder, chemotherapy: Treatment.Route) 