TrendMicro as well as US-CERT issued a warning about this piece of software from Apple. At the moment, there are two known QuickTime vulnerabilities, they're not very high risk but it's probably best to stay on the safe side and just get rid of QuickTime.
Computers running QuickTime for Windows will continue to work after support ends. However, using unsupported software may increase the risks from viruses and other security threats. Potential negative consequences include loss of confidentiality, integrity, or availability of data, as well as damage to system resources or business assets. The only mitigation available is to uninstall QuickTime for Windows.Details on how to uninstall QuickTime can be found over here.