Kang S, Southard T, et al. DNA damage is a feature of feline injection-site sarcoma. Vet Comp Oncol. 2017 Jun;15(2):518-524. 

Injection site sarcomas in cats are a serious sequela that may occur following injections such as vaccinations. These soft tissue cancers are locally aggressive, may metastasize, and are difficult to treat. Damage to DNA and the ability of a cell to repair this damage may impact the success of treatment using chemotherapy. The more damage to the DNA of the involved neoplastic cells, the more resistant to successful treatment with chemotherapy. These investigators hypothesized that injection site sarcomas may have underlying DNA damage, and that attempts by the cell to repair this damage may contribute to the resistance of some cats to chemotherapeutics.

They assessed the presence of DNA damage in these sarcomas through evaluation of a particular protein which is made in response to DNA damage. They found that, out of 17 cats evaluated, the level of this protein varied significantly. This is a reflection of the amount of DNA damage and may explain why the efficacy of chemotherapy for injection site sarcomas varies among treated cats. They conclude that DNA damage does occur in injection-site sarcomas and may contribute to the resistance of some cats to chemotherapeutic drugs. Measurement of this protein may be a useful prognostic indicator of treatment success.  (MK)