Breast Cancer HCC Coding Guide
Breast Cancer (e.g. C50.011) maps to HCC 23 (Prostate, Breast, and Other Cancers and Tumors) under the CMS-HCC V28 risk adjustment model, with a community, non-dual, aged RAF weight of 0.186; V28 reached 100% phase-in for payment year 2026. Z85.3, personal history of malignant neoplasm of breast, is non-HCC under V28. It can also map to HCC 18 (Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid) when the documentation supports those manifestations.
Complete HCC coding guide for Breast Cancer (C50.x) including ICD-10 to HCC mapping, V28 RAF weights, laterality documentation, and active vs. history coding.
Medically reviewed by Jess P., CPC · Reviewed: May 10, 2026 · Updated for CMS-HCC V28 and FY2026 ICD-10-CM
Quick Facts
HCC Categories
HCC 18, Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid
HCC 23, Prostate, Breast, and Other Cancers and Tumors
RAF Weight Range
0.186 to 2.341
Community, non-dual, aged (V28)
Model
CMS-HCC V28 (PY2026, 100% phase-in)
9 ICD-10 codes map to payment HCCs
What HCC category does Breast Cancer map to under V28?
Breast cancer is the most commonly diagnosed cancer in women in the United States. Under CMS-HCC V28, an active primary breast malignancy (C50.x) maps to HCC 23, "Prostate, Breast, and Other Cancers and Tumors," which carries a community non-dual aged RAF of 0.186. The picture changes when distant spread is documented. A secondary (metastatic) neoplasm code such as C79.81 maps to HCC 18, "Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer," at a much higher RAF of 2.341. So a single patient's codes can land in two HCCs. Coders must verify disease status at every encounter, because personal history of breast cancer (Z85.3) carries no HCC once disease is no longer active.
ICD-10 to HCC Mapping
| ICD-10 Code | Description | Billable | HCC Mapping |
|---|---|---|---|
| C50.011 | Malignant neoplasm of nipple and areola, right female breast | Yes | HCC 23 |
| C50.012 | Malignant neoplasm of nipple and areola, left female breast | Yes | HCC 23 |
| C50.411 | Malignant neoplasm of upper-outer quadrant of right female breast | Yes | HCC 23 |
| C50.412 | Malignant neoplasm of upper-outer quadrant of left female breast | Yes | HCC 23 |
| C50.911 | Malignant neoplasm of unspecified site of right female breast | Yes | HCC 23 |
| C50.912 | Malignant neoplasm of unspecified site of left female breast | Yes | HCC 23 |
| C50.919 | Malignant neoplasm of unspecified site of unspecified female breast | Yes | HCC 23 |
| C50.419 | Malignant neoplasm of upper-outer quadrant of unspecified female breast | Yes | HCC 23 |
| C79.81 | Secondary malignant neoplasm of breast | Yes | HCC 18 |
| Z85.3 | Personal history of malignant neoplasm of breast | Yes | No HCC (not risk-adjusting under V28) |
RAF weights are community, non-dual, aged base coefficients from the CMS-HCC V28 model (PY2026). Verify against the latest CMS rate announcement for payment calculations.
HCC Buddy maps Breast Cancer from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Documentation Tips
Document the specific quadrant or site within the breast: upper-outer, upper-inner, lower-outer, lower-inner, central, or axillary tail.
Always specify laterality: right, left, or bilateral, unspecified laterality results in less specific codes.
Clearly document whether the breast cancer is currently active (under treatment or surveillance) or represents personal history.
Record the receptor status (ER, PR, HER2) when available, as it supports the specificity of documentation.
Document current treatment modality: surgery, chemotherapy, radiation, hormonal therapy, or immunotherapy.
Code metastatic sites (C77-C79) separately when distant metastases are documented.
Common Coding Mistakes
Coding active breast cancer (C50.x) for a patient who completed treatment and is in remission, use personal history Z85.3 when cancer is no longer active.
Failing to specify laterality, resulting in unspecified-side codes that reduce clinical specificity.
Not coding the quadrant when it is documented in surgical pathology or imaging reports.
Missing metastatic site codes when the patient has documented distant disease (bone, liver, brain, lung metastases).
V24 to V28 Changes
Under CMS-HCC V28, active primary breast cancer (C50.x) maps to HCC 23, "Prostate, Breast, and Other Cancers and Tumors," a lower-weighted category (RAF 0.186) reflecting localized, treatable disease. This is a step down in granularity from the prior model, where breast, prostate, and similar tumors shared a single broad cancer category. The important V28 nuance is the split between the primary site and documented metastasis. If a secondary neoplasm code like C79.81 is supported, it drives HCC 18 (metastatic cancer, RAF 2.341) on top of, or in place of, the primary mapping. Capturing both the active primary code and any documented distant spread is what determines accurate risk capture, not the C50 code alone.
Related Conditions
Related references
Sources
RAF weights are community, non-dual, aged base coefficients from the CMS-HCC V28 model (PY2026). Verify against the latest CMS Rate Announcement for payment.
Verified current to CMS-HCC V28, payment year 2026 — last reviewed May 10, 2026.
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