In univariable analysis of dogs receiving adjunctive therapy for MCTs, which factors showed significant differences in survival when analyzed individually?

• A. Kiupel grade, mitotic count, and KIT immunolabeling pattern
• B. Beclin-1 immunolabeling
• C. Kiupel grade only
• D. Mitotic count only

Answer: (A)

In univariable survival analysis, each factor is tested on its own to see if it associates with survival outcomes. Kiupel grade captures the overall histologic aggressiveness of a canine mast cell tumor; higher grade tumors consistently behave more aggressively, translating to shorter survival when analyzed separately. Mitotic count reflects how actively the tumor cells are dividing; a higher mitotic index indicates a more proliferative tumor and poorer prognosis in isolation. KIT immunolabeling pattern indicates how the KIT receptor is organized in the tumor cells; aberrant patterns (such as cytoplasmic or disrupted membranous staining) are linked to more malignant behavior and worse survival when looked at alone. Beclin-1 immunolabeling, while of interest for autophagy-related biology, did not show a significant association with survival when evaluated without adjusting for other factors in this dataset. Therefore, the factors that stand out as significant in univariable analysis are Kiupel grade, mitotic count, and KIT immunolabeling pattern.