title: Apoptosis and Ki-67 as predictive factors for response to radiation therapy in feline nasal lymphomas.
abstract: Nasal lymphoma is the most common nasal tumor in cats and is generally a solitary and radiosensitive tumor. We retrospectively evaluated the response to radiation and survival time in relation to apoptosis and Ki-67 indices in feline nasal lymphomas treated with radiation therapy. The apoptotic and Ki-67 indices were evaluated with TUNEL and immunohistochemical staining in 30 biopsy tissues that were taken before any treatment. These two indices were compared, and differences between different treatment response groups were analyzed. The correlation between the median survival times (MST) and the indices was estimated using the Kaplan Meier method, and statistical differences between survival curves were analyzed using a log-rank method. With regard to apoptotic index, a statistical difference was observed between the samples taken from cats with complete response and stable disease (1.22% vs. 0.45%; P=0.045). The Ki-67 index in cats with both complete response and partial response was significantly higher than in cats with stable disease (44.4% and 39.6% vs. 16.3%; P<0.001 and P=0.008, respectively). The cats with a high level of apoptosis (>0.9%) nasal lymphoma were not significantly prolonged MSTs (P=0.202), however, high Ki-67-positive (>40%) cats experienced a statistically significant relationship with longer survival time (P=0.015). Our results indicate that spontaneous apoptotic and Ki-67 indices are strong predictors for response to radiation therapy in feline nasal lymphomas.
authors.affiliation: Laboratory of Veterinary Clinical Oncology, Small Animal Clinical Sciences, Graduate School of Veterinary Medicine, Rakuno Gakuen University, 582 Midorimachi, Bunkyodai, Ebetsu, Hokkaido 069-8501, Japan.
authors.forename: Dah-Renn
authors.initials: DR
authors.lastname: Fu
authors.forename: Daiki
authors.initials: D
authors.lastname: Kato
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Endo
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kadosawa
mesh_terms: D000818:Animals; D017209:Apoptosis; D001706:Biopsy / Q000662:veterinary; D002371:Cat Diseases / Q000503:physiopathology / Q000532:radiotherapy*; D002415:Cats; D005260:Female; D019394:Ki-67 Antigen / Q000378:metabolism*; D008223:Lymphoma / Q000378:metabolism / Q000503:physiopathology / Q000532:radiotherapy / Q000662:veterinary*; D008297:Male; D009669:Nose Neoplasms / Q000378:metabolism / Q000503:physiopathology / Q000532:radiotherapy / Q000662:veterinary*; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D019394:Ki-67 Antigen