All valid points. Thank you! Aside from tinting, what other options would you suggest? 

Brow/lash tint can be done provided:

The client has no sensitivity in and around eyes from chemo; depends how much chemo they have had and whether hair will hold tint with drug in system.  Be prepared to answer the question if client has a reaction or the hair falls out after application - whether or not it has to do with you applying tint....could be that hair was going to fall out.  So, there are lots of questions to be asked....there are also other options if tint is not the answer.