DNA damage is present in a variety of cancers, and animals have evolved ways of repairing DNA damage to maintain the integrity of this important means of transferring genetic information. Now a group of Cornell researchers funded by the Cornell Feline Health Center has demonstrated that DNA damage is a common feature of feline injection site sarcomas (FISS), a type of cancer that typically arises at the sites of injections in cats. The discovery represents an important step in understanding how this cancer arises and spreads, and perhaps in predicting how individual cases of FISS may respond to chemotherapy. Read the research article. FISS can develop in the weeks, months, or years following immunization and they can be very invasive and spread easily. Surgical management of this aggressive cancer can be extremely disfiguring and difficult. Chemotherapy for FISS is often not successful, and understanding the mechanism behind the lack of response of FISS to chemotherapy holds promise for improving our ability to treat this dreadful feline disease. The findings funded by the Cornell Feline Health Center may pave the way for improved diagnostic and therapeutic options for FISS, which would significantly improve the lives of cats afflicted with this clinically challenging condition.