Beclin-1 expression across disease stages in canine mast cell tumors shows the only statistically significant difference between which categories and what is the P-value?

• A. Primary tumors and lymph node metastases (P = .001)
• B. Primary tumors and recurrences (P = .01)
• C. Recurrences and lymph node metastases (P = .02)
• D. Primary tumors and recurrences (P = .005)

Answer: (A)

Beclin-1 is an autophagy-related marker, and its level can reflect how autophagy activity changes as a tumor progresses. In this study, the only statistically significant difference in Beclin-1 expression occurs when comparing primary tumors to lymph node metastases, with a P-value of 0.001. This strong, unlikely-to-be-due-to-chance result indicates that Beclin-1–associated autophagy is regulated differently between the initial tumor site and metastatic involvement in the lymph node. The direction of change (whether Beclin-1 is higher or lower in metastases) depends on the data, but the key point is that this particular transition shows a real difference, whereas other stage comparisons did not reach the same level of statistical significance under the study’s criteria. This highlights how autophagy-related pathways can shift as tumors spread, signaling a potential role for Beclin-1–mediated processes in nodal metastasis.