1975
Because there is little information on the expression of topo I in colorectal tumors , this study evaluated and characterized topo I protein expression in primary colorectal cancer and lymph node metastases and studied the association between topo I protein expression and clinicopathologic data , p53 status , and proliferating cell nuclear antigen ( PCNA ) status .
 colorectal tumors, primary colorectal cancer, lymph node metastases
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Anatomy 
Text: {0} 
Answer:
 colorectal tumors, primary colorectal cancer, lymph node metastases