Genetic Markers in Patients With Colorectal Cancer

OBJECTIVES:

- Determine the clinical and pathologic significance of unstable DNA elements in
colorectal cancer (tumor microsatellite instability).

- Determine the clinical and pathologic significance of loss of heterozygosity for
chromosomes 5, 8, 17, and 18 (as the primary targets) and of chromosomes 1, 14, and 22
(as the secondary targets) in colorectal cancer.

OUTLINE: DNA is examined for unstable elements (microsatellite instability and loss of
heterozygosity) by analyzing at least 10 separate (CA)n-repeats localized to 5 separate
chromosomes (5q, 8p, 15, 17p, and 18q). Loss of heterozygosity is analyzed for at least four
chromosomal arms (5q, 8p, 17p, and 18q) and later other chromosomes (e.g., 1, 14, and 22).
Immunohistochemistry is used to test for the presence or absence of the genes involved in
DNA mismatch repair (hMLH1 and hMSH2).

Patients do not receive the results of the genetic testing and the results do not influence
the type or duration of treatment.

PROJECTED ACCRUAL: This study will accrue up to 708 specimens.

DISEASE CHARACTERISTICS:

- Must have had a resectable adenocarcinoma of the colon or rectum and must have
participated in one of the following NCCTG randomized clinical trials:

- 784852: No Treatment Control Versus Levamisole Versus Levamisole Plus
Fluorouracil (5-FU)

- 794604: No Treatment Control Versus 5-FU by Portal Vein Infusion

- 794751: Postoperative Radiation Versus Postoperative Radiation Plus Sequential
Chemotherapy with Methyl CCNU and 5-FU

- 844652: An Intergroup Study - An Evaluation of Levamisole Plus 5-FU as Surgical
Adjuvant Treatment for Resectable Adenocarcinoma of the Colon

- 864751: Phase III Protocol for Surgical Adjuvant Therapy of Rectal Carcinoma: A
Controller Evaluation of (A) Protracted-Infusion 5-FU as a Radiation Enhancer
and (B) 5-FU Plus Methyl-CCNU Chemotherapy

- 874651: M/N - A Controller Evaluation of Recombinant Interferon-gamma (IFL GM)
and 5-FU and Folinic Acid With or Without Levamisole as Adjuvant Treatment for
Resectable Adenocarcinoma of the Colon

- 894651: A Controller Phase III Evaluation of 5-FU Combined With Levamisole and
Leucovorin as Adjuvant Treatment for Resectable Colon Cancer

- Tissue blocks from the primary colorectal cancer must have been received by the NCCTG
operations office