This randomized, double-blind, placebo-controlled, multicenter trial evaluates the efficacy and safety of Antarctic krill oil in reducing side effects of intravesical therapy for non-muscle-invasive bladder cancer (NMIBC). A total of 210 participants (18-75 years) will be randomized to receive either 2g/day of krill oil capsules (containing phospholipids, DHA, EPA, and astaxanthin) or placebo during intravesical treatment (epirubicin, pirarubicin, or BCG).

Primary outcomes include bladder irritation symptoms (IPSS score), systemic adverse events, hematuria, and urinary tract infections. Secondary outcomes assess quality of life (QoL). Safety will monitor adverse events per CTCAE v5.0.

The study follows GCP standards and includes rigorous data management and ethical oversight. Results may offer a dietary intervention to improve treatment tolerance and QoL for bladder cancer patients.

This randomized, double-blind, placebo-controlled, multicenter clinical trial aims to evaluate the efficacy and safety of Antarctic krill oil functional food in alleviating side effects of intravesical therapy for bladder cancer. The study will enroll 210 participants (105 per group) aged 18-75 years with histologically confirmed non-muscle-invasive bladder cancer (NMIBC) who are scheduled to undergo postoperative intravesical therapy (e.g., epirubicin, pirarubicin, or BCG). Participants will be randomized to receive either 2g/day of krill oil capsules (containing phospholipids, DHA, EPA, and astaxanthin) or placebo (olive oil capsules) during their intravesical treatment period.

The primary outcomes include the reduction in bladder irritation symptoms (assessed via IPSS score), incidence of systemic adverse events (e.g., nausea, fatigue), hematuria, and urinary tract infections. Secondary outcomes focus on quality of life (QoL) improvements using standardized questionnaires. Safety monitoring will track adverse events related to krill oil or intravesical therapy, graded per CTCAE v5.0 criteria.

Statistical analyses will compare groups using t-tests, chi-square tests, repeated-measures ANOVA, and Cox regression models. The study anticipates a medium effect size (d=0.5) with 90% power and accounts for a 20% dropout rate. Conducted across three centers in China (Qilu Hospital of Shandong University, Qingdao University Affiliated Hospital, and Shandong Provincial Hospital), the trial adheres to GCP standards and includes rigorous data management, adverse event reporting, and ethical oversight. Results may offer a novel dietary intervention to improve tolerance and quality of life for bladder cancer patients undergoing intravesical therapy.

Inclusion Criteria:

• 1. Diagnosed bladder cancer: The patient needs to be diagnosed with bladder cancer through pathological examination and have undergone bladder cancer surgery.
• 2. Planned to receive bladder infusion therapy: Patients need to plan to receive bladder infusion therapy after surgery and agree to participate in the study.
• 3. Age range: 18 to 75 years old.
• 4. Normal blood, liver and kidney function: Laboratory tests showed that the patient's blood routine, liver function and kidney function were within the normal range.
• 5. Signed informed consent: The patient understands the content of the study and voluntarily signs the informed consent.

Exclusion Criteria:

• 1. Serious comorbidities: including but not limited to heart disease, severe liver and kidney insufficiency, uncontrolled hypertension, diabetes, etc.
• 2. History of allergies: Patients with a known history of allergy to krill oil or perfusion drug components.
• 3. History of prior chemotherapy: Patients who have received perfusion therapy prior to this study.
• 4. History of other malignant tumors: Patients with a history of other malignant tumors.
• 5. Pregnancy or lactation: Female patients who are pregnant or lactating.
• 6. Psychiatric illness: Patients with a history of severe psychiatric illness or currently receiving treatment for psychiatric illness.
• 7. Poor study compliance: Patients who believe that they are unable to complete the entire trial process as required by the study.
• 8. Other: Other conditions that the investigator considers unsuitable to participate in this study.

Both the participants and investigators are unaware of the group assignments, and the entire trial is arranged and controlled by the study designer.