The risk of breast cancer relapse decreases consistently for 10 years, then remains stable through 25 years, with ER-positive disease carrying higher risk than ER-negative disease from years 5 to 25, according to researchers.
At a median follow up of 24 years, the study reported outcomes of 4,105 patients who were diagnosed from 1978 to 1985 and participated in the International Breast Cancer Study Group Trials I to V. During the first 5 years of follow-up, risk of recurrence was lower for ER-positive compared with ER-negative disease: 9.9% vs. 11.5%. Beyond 5 years, risk was higher: 5-10 years, 5.4% vs. 3.3%; 10-15 years, 2.9% vs. 1.3%, 15-20 years, 2.8% vs. 1.2%. At 20-25 years, risk was 1.3% vs. 1.4% (P less than .001).
“We identified a population (ER positive) that maintains a significant risk of relapse even after more than 10 years of follow-up. New targeted treatments and different modes of breast cancer surveillance for preventing late recurrences within this population should be studied,” wrote Dr. Marco Colleoni of the European Institute of Oncology and International Breast Cancer Study Group, and colleagues (J Clin Oncol. 2016 Jan 18. doi: 10.1200/JCO.2015.62.3504).
For the entire patient group, breast cancer recurrence reached a peak at years 1-2 (15.2%), and decreased consistently through year 10 (5-10 years, 4.5%), then remained stable (10-15 years, 2.2%; 15-20, 1.5%; 20-25, 0.7%). Cumulative incidence of distant recurrence for the ER-positive group occurred less frequently than for the ER-negative group during the first 5 years and more frequently from 5 to 25 years: at 5 years, 27.1% vs. 23.4%; at 10 years, 31.9% vs. 31.8%; at 15 years, 35% vs. 33.4%; at 20 years, 37.4% vs. 34.1%; at 25 years, 38.3% vs. 35.3% (P less than .001).
All patients in the trials had undergone mastectomy and axillary clearance with at least eight nodes removed, with no locoregional radiotherapy, as was standard at the time.
Within the ER-positive group, patients who had zero to three positive nodes had had a stable risk of recurrence beyond 10 years, whereas for patients with four or more involved nodes, risk decreased gradually from 10 to 24 years.