Nicole Eggert -- who's battling cancer herself -- says she can sympathize with what Kate Middleton is now going through herself ... telling us there's a lot to juggle on this journey.

We talked to the actress Friday and she weighed in on Kate's announcement -- where she revealed she'd been diagnosed with cancer and was receiving preventative chemotherapy. Nicole, who has breast cancer, tells us there's a lot she can relate to with her own diagnosis.

For starters, NE says there's a lot of pressure having to weather this storm for public figures -- and perhaps even doubly so for someone like Kate ... who's a senior Royal.

Nicole says the public should lend her some grace during this time and not scrutinize as much as they have been ... because Kate will undoubtedly go through some changes in the near future, some of which she might not want to share with everyone despite the curiosity.

There's another element to this as well, and that includes how to deal with parenting her three young children as she and William navigate these choppy waters ... something Nicole tells us will be no easy task.

Take a listen to how she describes this -- NE says Kate not only has to process her diagnosis and manage how her body feels throughout this ... but she'll have her children to worry about as well, which is why a solid foundation at home and help will go a long way.

We also spoke with Dr. Lawrence Piro -- an oncologist from Los Angeles -- and he told us what Kate could come to expect as she continues on with her chemotherapy ... especially in terms of side effects, etc. Dr. Piro also made clear to us ... stress of any kind is not helpful.

With all that said, hopefully Kate can properly recover now and focus on what she needs to without all the gossip and speculation. At this point, it's obvious she's going through it.