This phase III trial studies how well nutrition therapy works in improving immune system in patients with bladder cancer that can be removed by surgery. Improving nutrition before and after surgery may reduce the infections and other problems that sometimes occur after surgery.

PRIMARY OBJECTIVE:

I. To compare the impact of consuming perioperative specialized immune-modulating drinks (SIM, Impact Advanced Recovery, Nestle) to oral nutrition supplement control drinks (ONS, Oral Nutrition Control, Nestle) on post-operative complications (any versus [vs.] none) within 30 days after scheduled radical cystectomy (RC).

SECONDARY OBJECTIVES:

I. To assess whether SIM use compared to ONS reduces late-phase post-operative complications within 90 days after scheduled RC.

II. To assess whether SIM use compared to ONS reduces infections. III. To assess whether SIM use compared to ONS reduces skeletal muscle wasting. IV. To assess whether SIM use compared to ONS reduces high grade post-operative complications.

V. To assess whether SIM use compared to ONS reduces readmission rates. VI. To assess whether SIM use compared to ONS improves quality of life. VII. To assess whether SIM use compared to ONS improves disease-free survival after surgery and overall survival.

TERTIARY OBJECTIVES:

I. To assess the impact of SIM use on the expansion of myeloid-derived suppressor cells.

II. To assess the impact of SIM use on pro-inflammatory cytokines and neutrophil: lymphocyte ratios.

III. To assess the impact of SIM use on post-operative arginine deficiency and amino acid metabolism.

IV. To explore the association of dietary intake variables (nutrition status, calories, protein, and immune-enhancing factors) and study outcomes.

TRANSLATIONAL MEDICINE OBJECTIVES:

I. To describe the microbiome of the gut in patients undergoing radical cystectomy and urinary diversion prior to initiation of immunonutrition or a nutrition control.

II. To define the microbiome change in patients undergoing radical cystectomy and urinary diversion after they have received blinded immunonutrition or control nutritional supplement.

III. To correlate cancer treatments, postoperative complications (specifically infections) and nutritional status with microbiome composition.

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM I: Patients receive SIM orally (PO) thrice daily (TID) on days -5 to -1 and 1-5. Patients undergo standard of care surgery on day 0.

ARM II: Patients receive placebo PO TID on days -5 to -1 and 1-5. Patients undergo standard of care surgery on day 0.

After completion of study, patients are followed up at 2, 30, and 90 days, and at 6, 9, 12, 18, 24, and 36 months after surgery.

Inclusion Criteria:

• Patients must have a tissue diagnosis of primary cell carcinoma of the bladder by transurethral resection of bladder tumor (TURBT) or partial cystectomy; patients may not have any evidence of unresectable disease or metastatic disease as assessed by exam under anesthesia or imaging (computed tomography [CT], magnetic resonance imaging [MRI], positron-emission tomography [PET])
• There must be plans for the cystectomy to be performed within 28 calendar days after registration
• Surgery must be planned to be performed under pre-approved, study-specific surgical guidelines
• Patients must have completed any neoadjuvant chemotherapy or immunotherapy (intravesical or systemic) >= 14 calendar days prior to registration and any toxicities resolved to at least grade 2
• Patients may have a history of radiation therapy; radiation therapy must have been completed >= 180 days prior to registration
• Patients may have a history of prior partial cystectomy; prior partial cystectomy must have been completed at least 180 days prior to registration
• Patients with planned adjuvant chemotherapy within 90 days after radical cystectomy will not be eligible
• Patients must be able to swallow liquid and have no refractory nausea, vomiting, malabsorption, or significant small bowel resection that would preclude adequate absorption; patients on tube feeding are not eligible
• Patients must have their baseline nutrition status assessed using the Scored Patient-Generated Subjective Global Assessment (PG-SGA) by a clinician or licensed healthcare practitioner (trained physician, nurse, or dietician) within 14 days prior to registration and must not have a global category rating of stage C (severely malnourished)
• Patients must not have galactosemia
• Patients must not have known active viral infections such as human immunodeficiency virus (HIV) or hepatitis, as these chronic viral infections may cause cachexia and immunodeficiency and thus alter the biology regarding the study endpoints
• No other prior malignancy is allowed except for the following: adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, adequately treated stage I or II cancer from which the patient is currently in complete remission, or any other cancer from which the patient has been disease free for two years; prostate cancer found at cystectomy would not be considered a prior malignancy
• Patients must not be pregnant or nursing as the conditions preclude candidacy for radical cystectomy
• Patients must consent and be willing to have specimens collected and submitted
• Patients must be offered the opportunity to participate in additional specimen banking
• Patients or their legally authorized representative must be informed of the investigational nature of this study and must sign and give written informed consent in accordance with institutional and federal guidelines
• As a part of the Oncology Patient Enrollment Network (OPEN) registration process the treating institution's identity is provided in order to ensure that the current (within 365 days) date of institutional review board approval for this study has been entered in the system
• Patients must consent and provide their telephone contact information for four 24-hour dietary recall phone interviews to be conducted by staff at the Exercise, Diet, Genitourinary, & Endocrinology Laboratory (EDGE) Research Laboratory
• Patients must be able to understand and speak English and/or Spanish because the dietary recall phone interviews will only be conducted in English or Spanish