Adjuvant ovarian ablation vs CMF chemotherapy in premenopausal breast cancer patients: trial update and impact of immunohistochemical assessment of ER status

This trial, initiated in 1980, examined the relative values of adjuvant ovarian ablation and chemotherapy comprising cyclophosphamide, methotrexate and 5-fluorouracil (CMF) in premenopausal women with pathological stage II breast cancer. With median follow-up for patients still alive of 13.9 years, there is no difference in survival between women receiving ovarian ablation and CMF (hazard ratio 1.01; 95% CI: 0.74, 1.37). Tumour oestrogen receptor (ER) status was assessed at the time using biochemical ligand-binding assay and retrospectively by immunohistochemistry (IHC). Agreement between these two methods was only fair, but both confirmed the importance of ER status in determining appropriate adjuvant systemic therapy. A statistically significant interaction between IHC quick score and treatment (P=0.001) showed ovarian ablation was more beneficial for patients with a positive quick score, whereas women with a quick score of 0 had a significantly higher risk of death with ovarian ablation (2.33; 95% CI: 1.30, 4.20). We have shown that IHC identifies women with ER ‘poor’ tumours for whom endocrine manipulation is not appropriate.