Possibly some versions accept startup options beginning with - as well as / -- but if so, I wouldn't depend on it continuing to future releases! Don't rely on undocumented behavior if there's an easy way not to.
C:\Temp >cmd /?
Starts a new instance of the Windows command interpreter
CMD [/A | /U] [/Q] [/D] [/E:ON | /E:OFF] [/F:ON | /F:OFF] [/V:ON | /V:OFF]
[[/S] [/C | /K] string]
/C Carries out the command specified by string and then terminates
/K Carries out the command specified by string but remains