• Feasibility of detecting tumor-specific DNA mutations and DNA methylation abnormalities in biological fluids vs in tumor biopsies or resected tumor tissue [ Designated as safety issue: No ]
  

• Detection of tumor-specific nucleic acids as markers of active disease [ Designated as safety issue: No ]
  
• Correlation of known markers of inflammation and fibrosis with gastrointestinal toxicity [ Designated as safety issue: Yes ]
  

OBJECTIVES:

Primary

• Determine if tumor-specific DNA mutations and aberrant DNA methylation can be detected in the serum, urine, or stool at the time of diagnosis in patients undergoing radiotherapy for gastrointestinal malignancies.
• Determine if changes in mutational status at follow up are associated with disease persistence, recurrence, or survival of these patients.
• Determine if pre-treatment, post-treatment, and follow up measurements of TGFβ1 in the urine and plasma can be used to predict late gastrointestinal toxicity in these patients.

Secondary

• Determine which biological fluid (serum, urine, or stool) is most highly associated with the detection of tumor-specific DNA mutations and tumor-specific DNA methylation and provides the best source of tumor-specific DNA to measure at follow up for association with disease persistence, recurrence, or survival.
• Determine if novel serum, urine, and stool biomarkers obtained at the time of treatment and shortly after treatment can be used to predict the likelihood of chronic gastrointestinal toxicity in these patients.
• Determine if novel serum, urine, and stool biomarkers obtained at the time of treatment and shortly after treatment are influenced by the radiation dose delivered to abdominal organs in these patients.

OUTLINE: This is a pilot, prospective, longitudinal study.

Serum, plasma, urine, and stool samples are collected prior to any treatment, prior to radiotherapy, at completion of radiotherapy, and at 1, 3, 6, 12, 24, and 36 months after completion of radiotherapy for research studies. Tumor tissue collected at biopsy or resection and biological samples are analyzed by polymerase chain reaction (PCR) and methylation-specific PCR.

PROJECTED ACCRUAL: A total of 120 patients will be accrued for this study.