Lymphosarcoma in cats is most frequently the result of feline leukemia (FeLV) or feline immunovirus (FIV). Both are typically genetic and both can be tested for, although a negative result does not necessasry mean that they have lifelong immunity. If they aren't already, please be sure all of the cats in this family lineage are spayed or neutered.
Yes....this is WAY beyond our scope in this community! I do totally understand your concern for the offspring, and I hope you get some answers.
Have you tried doing some research online? Or, you can post on our Ask A Vet forum also on MedHelp!!
Best wishes to you and for the kids to grow up healthy and happy! =)
PS-Please, come on back and let us know what you find out.
I'm so sorry to hear of your cat. We aren't Veterinarians on this site, we are only pet owners like you....we share information with one another from personal experience and I'm not at all familiar with the sarcoma you are looking for answers about(maybe someone else on here will be able to help)
I can give you another site that may or may not lead to some answers....good luck with the other kitties and with the search too.
http://www.marvistavet.com/html/body_feline_lymphoma.html