Comparison of WHO and RECIST Criteria for Evaluation of Clinical Response to Chemotherapy in Patients with Advanced Breast Cancer

When patients with advanced breast cancer (ABC) are treated with neoadjuvant chemotherapy (NACT),efficacy is monitored by the extent of tumor shrinkage. Since their publication in 1981, World Health Organization(WHO) guidelines have been widely practiced in clinical trials and oncologic practice, for standardized tumorresponse evaluation. With advances in cancer treatment and tumor imaging, a simpler criterion based on onedimensionalrather than bi-dimensional (WHO) tumor measurement, named Response Evaluation Criteriain Solid Tumors (RECIST) was introduced in 2000. Both approaches have four response categories: completeresponse, partial response, stable disease and progressive disease (PD). Bi-dimensional measurement data of151 patients with ABC were analysed with WHO and RECIST criteria to compare their response categoriesand inter criteria reproducibility by Kappa statistics. There was 94% concordance and 9/151 patients were recategorizedwith RECIST including 6/12 PD cases. RECIST therefore under-estimates and delays diagnosis ofPD. This is undesirable because it may delay or negate switch over to alternate therapy. Analysis was repeatedwith a new criteria named RECIST-Breast (RECIST-B), with a lower threshold for PD (≥10% rather than ≥20%increase of RECIST). This showed higher concordance of 97% with WHO criteria and re-categorization of only4/151 patients (1/12 PD cases). RECIST-B criteria therefore have advantages of both ease of measurement andcalculations combined with excellent concordance with WHO criteria, providing a practical clinical tool forresponse evaluation and offering good comparison with past and current clinical trials of NACT using WHOguidelines.