What is the ICD‑10 code for breast cancer?

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Last updated: September 15, 2026 • View editorial policy

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ICD-10 Codes for Breast Cancer

The primary ICD-10 code for malignant breast cancer is C50.x, with specific fourth and fifth digits indicating the precise anatomical location within the breast.

Primary Malignant Breast Cancer Codes

The ICD-10 coding system uses C50 as the base code for malignant neoplasm of breast, with additional digits specifying the exact location:

  • C50.0 - Nipple and areola
  • C50.1 - Central portion of breast
  • C50.2 - Upper inner quadrant
  • C50.3 - Lower inner quadrant
  • C50.4 - Upper outer quadrant
  • C50.5 - Lower outer quadrant
  • C50.6 - Axillary tail
  • C50.8 - Overlapping lesion of breast
  • C50.9 - Breast, unspecified

Each of these requires a fifth digit to specify laterality (right, left, or unspecified).

Carcinoma In Situ (Non-Invasive)

For ductal carcinoma in situ (DCIS) and other non-invasive breast lesions, use:

  • D05.0 - Lobular carcinoma in situ (LCIS)
  • D05.1 - Intraductal carcinoma in situ (DCIS)
  • D05.7 - Other carcinoma in situ of breast
  • D05.8 - Carcinoma in situ of breast, unspecified
  • D05.9 - Carcinoma in situ of breast, unspecified site

1, 2, 1

Paget's Disease

D05.0-D05.9 codes are used for Paget's disease of the nipple when NOT associated with underlying invasive carcinoma. When Paget's disease is associated with invasive breast cancer, code based on the invasive component using C50.x codes 3, 4.

Critical Coding Considerations

Position Matters for Accuracy

When using administrative databases for research or quality metrics, principal (primary) discharge diagnosis codes have significantly higher positive predictive value (92.1%) compared to secondary codes 5. The combination of principal discharge codes OR secondary codes plus imaging procedure codes yields the best balance of sensitivity (81.6%) and PPV (84.7%) 5.

Common Pitfalls

  • Avoid using C54.x codes - these are for uterine/endometrial cancer, not breast cancer
  • Laterality specification is mandatory for accurate coding in clinical practice
  • Outpatient diagnosis codes have lower confirmation rates (69.8% for breast cancer) compared to inpatient codes, so validation with treatment codes (surgery, chemotherapy, radiation) improves accuracy 6
  • ICD-10 coding quality varies by setting: agreement rates for principal diagnosis codes range from 79-87% at the 4-digit level 7

Validation Strategy

For research or registry purposes, confirm breast cancer diagnoses by requiring either: persistence (subsequent diagnosis codes or death within one quarter) OR congruence with treatment codes (surgical procedures, chemotherapy, or radiation therapy codes) to improve case identification accuracy from approximately 70% to over 85% 6, 8.

References

1
Guideline

breast cancer, version 4.2017, nccn clinical practice guidelines in oncology.

Journal of the National Comprehensive Cancer Network : JNCCN, 2018

6
Research

[ICD coding quality for outpatient cancer diagnoses in SHI claims data].

Zeitschrift fur Evidenz, Fortbildung und Qualitat im Gesundheitswesen, 2016

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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.