What ICD-10 (International Classification of Diseases, 10th Revision) codes are used for a patient undergoing radiation therapy for prostate cancer?

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Last updated: October 1, 2025View editorial policy

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ICD-10 Codes for Patients Receiving Radiation Therapy for Prostate Cancer

For a patient receiving radiation therapy for prostate cancer, the primary ICD-10 code is C61 (Malignant neoplasm of prostate) along with the appropriate Z51.0 (Encounter for antineoplastic radiation therapy) code. 1

Primary Diagnosis Code

  • C61: Malignant neoplasm of prostate
    • This is the primary diagnosis code that must be listed first to identify the condition being treated

Radiation Therapy Encounter Code

  • Z51.0: Encounter for antineoplastic radiation therapy
    • This code should be used as a secondary code to indicate the purpose of the encounter is for radiation therapy

Additional Codes That May Be Required

Depending on the specific clinical scenario, additional codes may be necessary:

  • Z85.46: Personal history of malignant neoplasm of prostate (if the patient has completed initial treatment and is receiving adjuvant radiation)
  • Z92.3: Personal history of irradiation (if the patient has received radiation therapy in the past)

Coding Based on Stage of Disease

For more specific documentation, consider adding stage-specific codes:

  • For localized disease: C61 + Z51.0
  • For locally advanced disease: C61 + Z51.0
  • For metastatic disease: C61 + appropriate metastasis code (C77.x-C79.x) + Z51.0

Radiation Modality Considerations

The ICD-10 code remains the same regardless of the radiation modality used 1:

  • External beam radiation therapy (EBRT)
  • Intensity-modulated radiation therapy (IMRT)
  • Stereotactic body radiation therapy (SBRT)
  • Brachytherapy (HDR or LDR)

Common Coding Pitfalls to Avoid

  1. Missing the Z51.0 code: Always include this code for radiation therapy encounters
  2. Using history codes inappropriately: Only use Z85.46 when cancer has been treated and is no longer present
  3. Failing to code metastases: When present, metastatic sites must be coded separately
  4. Not updating codes when treatment changes: If a patient moves from active treatment to surveillance, codes should reflect this change

Coding for Treatment Planning vs. Delivery

  • For the initial consultation and planning visit: Use C61 as primary
  • For actual radiation delivery sessions: Use C61 + Z51.0

Remember that while CPT codes will vary based on the complexity and type of radiation treatment delivered, the ICD-10 diagnosis codes remain consistent throughout the course of radiation therapy for prostate cancer 1.

References

Guideline

Radiation Therapy Coding for Prostate Cancer

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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