Questions About Cancer? 1-800-4-CANCER
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NCI Dictionary of Cancer Terms


  A specific part of chromosome 9 called p21, which has a gene that may be involved in stopping tumor cell growth. In some types of cancer cells, including bladder cancer cells, this small part of chromosome 9 may be missing. This may cause cancer cell growth. Checking for 9p21 may help diagnose cancer or find out if cancer has come back. 9p21 is a type of tumor marker.