Proportion of HER2-positive primary and metastatic breast cancers*
| 0 | 1+ | 2+ | 3+ | ISH + | Overall HER2- positive | |
|---|---|---|---|---|---|---|
| Overall (%) | 32.8 | 33.1 | 21.8 | 11.6 | 14.7 | 14.5 |
| Primary carcinoma (%) | 32.6 | 33.7 | 21.8 | 11.5 | 14.6 | 14.3 |
| Metastatic lesion (%) | 36.7 | 27.2 | 21.1 | 14.9 | 15.8 | 18.0* |
*UK NEQAS ICC & ISH combined 5 year national audit data (unpublished data).
ISH, in situ hybridisation; ISH+, proportion of 2+ carcinomas that are amplified; UK NEQAS ICC & ISH, UK National External Quality Assessment Scheme for Immunocytochemistry and In Situ Hybridisation.