The goal of this clinical trial is to learn if adding Huaier Granule to standard care can treat proteinuria (excess protein in the urine) in adult female breast cancer patients (aged 18-75) who developed this condition as a side effect of their immunotherapy or anti-angiogenic cancer treatment.

The main question it aims to answer is:

* Does the addition of Huaier Granule to standard care improve the effectiveness of proteinuria treatment after 8 weeks?

Researchers will compare the group receiving standard care plus Huaier Granule to the group receiving standard care alone to see if the combination is more effective at reducing protein levels in the urine.

Participants will:

• Be randomly assigned to one of the two study groups.
• Continue their prescribed anti-cancer therapy (immunotherapy or anti-angiogenic therapy).
• Receive standard medical care for proteinuria from a kidney specialist.
• If in the experimental group, take Huaier Granule orally, three times a day.
• Attend clinic visits every 4 weeks for up to 24 weeks for check-ups and tests, including urine and blood tests.

Inclusion Criteria:

• **Inclusion Criteria**

  1. Female patients aged 18-75 years.
  2. Histopathologically confirmed diagnosis of breast cancer.
  3. Currently receiving or having a prior history of immunotherapy and/or anti-angiogenic therapy.
  4. First-time detection of proteinuria on urinalysis, graded as +, ++, or +++.
  5. 24-hour urinary protein quantification between 0.15g and 3.5g (exclusive).
  6. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
  7. Karnofsky Performance Status (KPS) score ≥70.
  8. No prior treatment with Huaier Granule within one month before enrollment.
  9. Life expectancy of at least 6 months.
  10. Willingness to voluntarily participate in the study and provision of signed informed consent.

Exclusion Criteria:

• **Exclusion Criteria**

  1. Known history of chronic kidney disease (eGFR <60 ml/min/1.73m²) or diabetic nephropathy.
  2. Proteinuria attributed to other diseases, including but not limited to primary renal disease, hypertension, urinary tract infection, systemic lupus erythematosus, or multiple myeloma.
  3. Current use of ACEI/ARB medications (unless the dosage has been stable for ≥4 weeks prior to enrollment).
  4. Known allergy, contraindication, or specific precaution to any component of Huaier Granule.
  5. Women who are pregnant, breastfeeding, or planning to conceive.
  6. Concurrent participation in any other clinical trial investigating medications for proteinuria.
  7. Any other condition that, in the judgment of the investigator, would make the patient unsuitable for participation in this study.