Adjuvant Chemotherapy Reduces Local and Regional Tumor Recurrence, Especially for Patients with ER-Negative Breast Cancer
Adjuvant chemotherapy should be recommended for patients with completely resected, isolated local or regional recurrence (ILRR) of breast cancer, and the argument is strongest for women with estrogen receptor (ER)-positive tumor recurrences, according to the results of the international Chemotherapy as Adjuvant for Locally Recurrent Breast Cancer (CALOR) trial.
Stefan Aebi, MD, Head of Medical Oncology, Luzerner Kantonsspital, Lucerne, Switzerland, reported that, for patients with ILRR, adjuvant chemotherapy reduced the risk of recurrences by 41% and the risk of death by 59% in CALOR, which is reportedly the first randomized controlled trial to show a benefit of adjuvant chemotherapy in these patients.
Traditionally, the prognosis of women with ILRR has been poor, Dr Aebi pointed out, with a disease-free survival of approximately 50% at 5 years. Surgery and radiation therapy represent the standards of care for this patient population, but the recent findings from the CALOR trial may suggest an emerging role for adjuvant chemotherapy in some of these women.
A heterogeneous group of 162 patients took part in the CALOR trial. After mastectomy or breast-conserving surgery, the women were stratified by hormone receptor status of ILRR, site of tumor recurrence (ie, breast, chest wall, lymph nodes), and the use of previous chemotherapy. Chemotherapy was by physician’s choice, but the suggested approach was a combination of at least 2 drugs for 3 to 6 months of treatment.
Radiation therapy was recommended for all the women, but was mandatory only for those with microscopically involved margins.
At 4.9 years of median follow-up, the 5-year disease-free survival probability was 69% in the group that received chemotherapy compared with 57% for those who did not receive chemotherapy, Dr Aebi reported.
“The 12% absolute difference at 5 years corresponds to a hazard ratio of 0.59, or a 41% relative reduction in the risk of tumor recurrence, which is statistically significant, with a P value of .045,” he said.
Based on the disease-free survival data that were categorized by ER status, the efficacy of chemotherapy was “huge” for those with ER-negative tumor recurrences (hazard ratio, 0.32; P = .007). In contrast, the difference was marginal in the women with ER-positive tumors, Dr Aebi reported.
In terms of overall survival, at 5 years of median follow-up, the relative survival rate was 88% in the women who received chemotherapy compared with 76% in those who did not receive chemotherapy, corresponding to a relative risk reduction of 59%. The survival analysis based on ER status is still premature, Dr Aebi added.