This is a pilot study to assess acute toxicity in patients receiving flank irradiation using proton therapy for renal tumors.

Patients with renal tumors including Wilms and clear cell sarcoma of the kidney (CCSK) are treated with multimodality therapy which may include surgery, chemotherapy, and radiation. While long-term disease control is excellent, these patients remain at risk for early and late toxicities partially from radiation. There have been no significant changes to traditional photon radiation fields, which encompass the post-operative bed, anterior abdomen, and vertebral body. Proton beam radiation using pencil beam scanning, which is characterized by Bragg peak dose deposition and high conformality of dose to target regions, is ideally suited to treat the retroperitoneum. This pilot study evaluates pencil beam scanning proton therapy (PBS-PT) to:

• result in low acute gastrointestinal toxicity in patients receiving radiation therapy for renal tumors as measured by laboratory evaluations, clinician-assessed, and patient reported health related quality of life outcomes
• decrease the duration of radiation therapy
• compare doses to organs at risk (OARs) using PBS-PT as compared to traditional photon fields

Inclusion Criteria:

• Less than 30 years of age

• Diagnosis

  a. Any patient with Wilms tumor or clear cell sarcoma of the kidney who would require radiation therapy as standard of care including

  1. Any patient with favorable histology (FH), stage III disease
  2. Any patient with focal or diffuse anaplasia
  3. Any patient with CCSK

• The patient is a candidate for external beam radiotherapy based on standard of care for treatment of Wilms tumor or CCSK

Exclusion Criteria:

• Prior radiotherapy to the region of the study cancer
• Chemotherapy administered for diagnosis of Wilms tumor or CCSK
• Pregnant or breastfeeding