Residual cancer burden (RCB)

In one sentence

Residual cancer burden combines breast tumor-bed measurements and regional-node findings into a score after neoadjuvant treatment.

The intuition

Imagine describing what is left using both its footprint and how much of that footprint contains invasive cancer. A large treated bed can contain sparse viable cells. RCB combines this with node findings rather than using the longest tumor dimension alone.

How it works

The calculation uses two tumor-bed dimensions, overall cancer cellularity and the proportion that is in situ, plus the number of involved nodes and the largest nodal metastasis. The method combines them into a continuous score. RCB-0 corresponds to pCR (pathologic complete response); RCB-I, II and III describe increasing residual burden under the validated classification.

Cellularity is the proportion of the evaluated tumor bed occupied by cancer under the scoring method. It differs from the purity estimate used in sequencing a selected sample. A low cellularity does not mean every part of the bed or every node is free of cancer.

RCB is prognostic in studied breast-cancer populations, but an RCB class is not a single personal recurrence probability. Receptor subtype, treatment era, follow-up, clinical stage and subsequent therapy affect how a cohort applies. The score does not establish that an investigational vaccine works best in one class or needs more boosters in another.

RCB and ypTNM answer related but different questions: one summarizes residual burden, the other classifies residual anatomic extent. Neither replaces the report’s margins, receptor findings or other local-management details.

Why it matters in cancer

It provides a reproducible description of residual disease, while keeping prognostic evidence separate from the choice of additional treatment.

Worked example

Two specimens share the same tumor-bed size. One has sparse invasive cells and negative nodes; the other has dense invasive cells and several involved nodes. Their RCB can differ because all those measurements contribute. Do not calculate a class from the bed size alone.

Common confusions

RCB-II means a residual-burden category, not “stage II.”
RCB is not interchangeable with a percentage of living cells in a sequencing tube.
Prognostic association does not establish benefit from a proposed additional drug.

pCR and TNM staging.

Sources and scope

General teaching, source-checked October 8, 2026. The examples are hypothetical unless a study is explicitly named. Expert and learner review remain pending.