Inclusion Criteria:

          -  Participants must meet all the following criteria in order to be eligible to
             participate in the study:

          -  Histologically or cytologically confirmed T 3/4 or N+ (> 1 cm in size or FDG avid)
             Siewart 1-3 gastroesophageal (GE) junction or esophagogastric cancer. Diagnosis must
             be confirmed by a DF/HCC institution pathology department prior to registration.

          -  Age 18 years or older. There will be no upper age restriction.

          -  ECOG performance status ≤ 1

          -  Life expectancy of greater than 3 months

          -  Participants must have adequate organ and marrow function as defined below:

               -  absolute neutrophil count ≥ 1,500 cells/mm3

               -  platelets ≥ 75,000 cells/mm3

               -  total bilirubin ≤ 1.5 x upper limit of normal OR for patients who have undergone
                  biliary stenting, total bilirubin of ≤ 2.0 x upper limit of normal OR two down
                  trending values.

               -  AST(SGOT) ≤ 2.5 x upper limit of normal

               -  ALT (SGPT) ≤ 2.5 x upper limit of normal

               -  creatinine ≤ 1.5 mg/dL OR creatinine clearance ≥ 30 mL/min/1.73 m2 for
                  participants with creatinine levels above institutional normal.

          -  The effects of both radiation therapy and the chemotherapy agents used in this trial
             are known to be teratogenic. Therefore, women of child-bearing potential and men must
             agree to use adequate contraception (hormonal or barrier method of birth control;
             abstinence) prior to study entry and for the duration of study participation plus 30
             days from the last date of study drug administration. Should a woman become pregnant
             or suspect she is pregnant while she or her partner is participating in this study,
             she should inform her treating physician immediately.

          -  Female subject of childbearing potential should have a negative urine or serum
             pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG). If the urine
             test is positive or cannot be confirmed as negative, a serum pregnancy test will be
             required.

          -  Ability to understand and the willingness to sign a written informed consent document.

        Exclusion Criteria:

          -  Participants who fulfill any of the following criteria will be excluded from the
             study:

          -  Evidence of metastatic disease as determined by chest CT scan, abdomen/pelvis CT scan
             (or MRI with gadolinium and/or manganese) within six weeks of study entry. Distant
             nodal disease is allowed if it is in the radiation port.

          -  Any prior chemotherapy, targeted/biologic therapy, or radiation for treatment of the
             participant's esophagogastric cancer.

          -  Treatment of other invasive carcinomas within the last five years with greater than 5%
             risk of recurrence at time of eligibility screening. Carcinoma in-situ and basal cell
             carcinoma/ squamous cell carcinoma of the skin are allowed.

          -  Receipt of any other investigational agents within 4 weeks preceding the start of
             study treatment.

          -  Serious concomitant systemic disorders incompatible with the study (at the discretion
             of the investigator), such as significant cardiac or pulmonary morbidity
             (e.g.congestive heart failure, symptomatic coronary artery disease and/or cardiac
             arrhythmias not well controlled with medication) or myocardial infarction within the
             last 12 months, or ongoing infection as manifested by fever.

          -  History of uncontrolled seizures, central nervous system disorders or psychiatric
             disability judged by the investigator to be clinically significant, precluding
             informed consent, or interfering with compliance or drug intake.

          -  Pregnant women are excluded from this study because radiation therapy and the
             chemotherapy agents to be used have the potential for teratogenic or abortifacient
             effects. Because there is an unknown but potential risk for adverse events in nursing
             infants secondary to treatment of the mother with these agents, breastfeeding should
             be discontinued while the mother is receiving protocol therapy.

          -  Major surgery, excluding laparoscopy, within 4 weeks of the start of study treatment,
             without complete recovery.

          -  No concurrent administration of cimetidine (as it can decrease the clearance of 5-FU).
             Another H2-blocker or proton pump inhibitor may be substituted before study entry.

          -  Known, existing uncontrolled coagulopathy.

          -  Prior systemic fluoropyrimidine therapy (unless given in an adjuvant setting and at
             least six months earlier). Prior topical fluoropyrimidine use is allowed.

          -  Known hypersensitivity to 5-fluorouracil or known DPD deficiency.

          -  History of allergic reaction(s) attributed to compounds of similar chemical or
             biologic composition to 5-fluorouracil, irinotecan, or oxaliplatin.