Leaving a cell out of a concatenate formula if another cell is blank

I have created the attached spreadsheet which pulls together various pieces of data a user enters and concatenates them into a string.

The content the user enters in C8 is optional. If the user leaves this blank then I do not want the content in C17 to be included in the results cell (B10). The results cell currently contains the following formula:

=CONCATENATE(C4,A14,C6,A15,C5,A16,C7,A17,C8)

How would I amend this to remove the info in A17 if C8 is left blank?

Thanks

Glayva