Using Ki67 Index to Select Appropriate Adjuvant Therapy for Early Breast Cancer
Posted: Tuesday, March 2, 2021
Researchers from the Institute of Cancer Research and the Royal Marsden NHS Foundation Trust, London, UK, found that 2 weeks of preoperative endocrine therapy appears to yield no improvement in the long-term outcome for postmenopausal women with hormone-sensitive early breast cancer, based on the results from the POETIC phase III trial. The trial confirmed a low risk of recurrence for those patients with a low baseline Ki67 index. According to Ian Smith, MD, of The Institute of Cancer Research, and colleagues: “The measurement of Ki67 is inexpensive, potentially making this an attractive approach to estimating the prognosis of patients with early breast cancer.” These findings were published in The Lancet Oncology.
This open-label, multicenter, randomized trial recruited participants from 130 UK hospitals. Participants were randomly allocated (2:1) to receive perioperative aromatase inhibitor treatment or no perioperative treatment (control) by computer-generated permuted block method. The perioperative treatment consisted of a nonsteroidal aromatase inhibitor in standard dosage (oral anastrozole at 1 mg/day or oral letrozole at 2 to 5 mg/day).
According to the researchers, the Ki67 index was evaluated as a biomarker in relation to its effect on predicting disease outcomes (one of the trial’s key objectives) and as the molecular secondary endpoint to assess the proliferation rate at baseline and at surgery. The study focused on 4,486 postmenopausal women with hormone-sensitive early breast cancer. The median age of patients at randomization was 67.1 years. After a median follow-up of 62.9 months, 434 women (10%) had a breast cancer recurrence.
The 5-year overall survival was 88.9% with the perioperative treatment versus 88.9% without treatment. The most common grade 3 adverse events in both groups were hot flushes and musculoskeletal pain.
The researchers concluded: “The data show no reason for short-term presurgical treatment to be applied for its direct therapeutic potential, but support prescribing an aromatase inhibitor for the short-term period before breast cancer surgery in estrogen receptor-positive tumors with a high proliferation rate to derive information on early endocrine responsiveness that can be used to predict a patient’s 5-year prognosis on standard adjuvant therapy.”
Disclosure: For full disclosures of the study authors, visit thelancet.com.
