RATIONALE: Studying samples of tumor tissue and blood from patients with cancer in the laboratory may help doctors learn more about changes that occur in DNA and identify biomarkers related to cancer. It may also help doctors predict how patients will respond to treatment.

PURPOSE: This clinical trial is studying how well biological factors work in predicting response to treatment in patients with esophageal cancer or rectal cancer.

OBJECTIVES:

Primary

• Analyze various biological factors that can be used as markers to predict response to treatment and correlate with the signaling pathway of EGFR.

Secondary

• Establish a tissue bank to store information about the response to treatment and survival.

OUTLINE: Patients undergo endoscopy, 11 biopsies of tumor tissue, and 3 biopsies of healthy mucosa. Blood samples are also collected. Samples are analyzed for the expression of 4 receptors in the EGFR family, polymorphisms at intron 1 of the EGFR gene, and gene mutations in downstream signaling pathways.

After surgery, patients are followed every 3 months.

DISEASE CHARACTERISTICS:

• Histologically confirmed adenocarcinoma or squamous cell carcinoma of the esophagus or rectum
• Planning to receive neoadjuvant treatment, including radiotherapy or chemoradiotherapy

PATIENT CHARACTERISTICS:

• Not pregnant or nursing
• No blood disorder
• Not deprived of freedom or protected by law

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics