Bu konuda hassas olunmalý.

my try

he/she must be sensitive about this subject

 Very close.  Olmalý is active. Olunmalý is passive.

So the strict translation:

This is a subject one has to be sensitive about.

Or for a more natural English flow:

This is a sensitive subject

or

We have to be careful about this subject.

THANK YOU

to be sensitive to not about