Which pair showed the only statistically significant difference in Beclin-1 expression across disease categories, with P = 0.001?

• A. Primary tumors vs lymph node metastases
• B. Primary tumors vs recurrences
• C. Recurrences vs lymph node metastases
• D. Primary vs recurrent vs lymph node metastases

Answer: (A)

The key idea is interpreting what a low P-value means for differences in a biomarker across disease categories. Beclin-1 is an autophagy-related protein, and its expression can vary as tumors progress from primary sites to recurrences or metastases. A P-value of 0.001 indicates a very strong, unlikely-to-be-due-to-chance difference between the two groups being compared.

In this scenario, Beclin-1 expression differs significantly between primary tumors and lymph node metastases, with only a 0.1% probability that this observed difference is due to random variation. That makes this pair the only one showing a real difference in Beclin-1 levels across the categories.

The other pairings (primary versus recurrences and recurrences versus metastases) did not reach this level of statistical significance, so the data do not provide evidence that Beclin-1 expression differs between those groups. The overall pattern suggests a distinct shift in Beclin-1 expression when tumors metastasize to lymph nodes compared with the original primary tumors.