Methods for detecting nucleic acids indicative of cancer

Abstract

The invention provides methods for screening tissue or body fluid samples for nucleic acid indicia of cancer or precancer.

1 . A method for screening a patient for cancer or precancer, the method comprising the steps of:
 detecting in a patient tissue or body fluid sample comprising exfoliated cells and cellular debris, nucleic acid fragments that are greater than 200 base pairs in length;   the presence of said fragments being a positive screen for cancer or precancer.   
     
     
         2 . The method of  claim 1 , wherein said detecting step comprises conducting an amplification reaction designed to amplify only nucleic acids in said sample that are greater than 200 base pairs in length. 
     
     
         3 . The method of  claim 1 , wherein said sample is selected from the group consisting of stool, pus, and urine. 
     
     
         4 . The method of  claim 1 , further comprising the step of enriching said sample for human DNA. 
     
     
         5 . The method of  claim 1 , further comprising the step of isolating human DNA from said sample. 
     
     
         6 . A method for screening a patient for cancer or precancer, the method comprising the steps of:
 determining in a patient tissue or body fluid sample a first amount of nucleic acid fragments greater than 200 base pairs in length;   determining in said sample a second amount of nucleic acid fragments less than about 200 base pairs in length;   determining a ratio between said first amount and said second amount; and   identifying a positive screen if said ratios exceeds a threshold ratio for patients who do not have cancer or precancer.   
     
     
         7 . A method for screening a patient for cancer or precancer, the method comprising the step of
 detecting in a patient tissue or body fluid sample comprising exfoliated cells a nucleic acid fragment of a length that is not expected to be present in said sample in a healthy patient;   the presence of said fragment being a positive screen.