Pathologic nodal status/breast tumor response following neoadjuvant chemotherapy can be used to predict locoregional recurrence in women with operable, palpable breast cancer (T1-3, N0-1, M0) previously treated with mastectomy or lumpectomy plus radiotherapy. These results from the combined analysis of the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-18 and B-27 trials were published in the Journal of Clinical Oncology.
The neoadjuvant chemotherapy used in the NSABP trials was either AC (doxorubicin/cyclophosphamide) alone or AC followed by neoadjuvant/adjuvant docetaxel. After 10 years of follow-up, 335 locoregional recurrence events had occurred in 3,088 patients.
“The 10-year cumulative incidence of [locoregional recurrence] was 12.3% for mastectomy patients (8.9% local; 3.4% regional) and 10.3% for lumpectomy plus breast radiotherapy patients (8.1% local; 2.2% regional),” the researchers reported. “Independent predictors of [locoregional recurrence] in lumpectomy patients were age, clinical nodal status (before [neoadjuvant chemotherapy]), and pathologic nodal status/breast tumor response; in mastectomy patients, they were clinical tumor size (before [neoadjuvant chemotherapy]), clinical nodal status (before [neoadjuvant chemotherapy]), and pathologic nodal status/breast tumor response. By using these independent predictors, groups at low, intermediate, and high risk [of locoregional recurrence] could be identified. Nomograms that incorporate these independent predictors were created.”
The authors noted that their nomograms could be useful in predicting the risk of locoregional recurrence and the optimal use of adjuvant radiotherapy in patients with neoadjuvant chemotherapy. Before such nomograms are used clinically, however, they need to be independently validated. The authors also recommended that future versions of the nomograms include information on the effect of hormone receptor status, HER2/neu status, and the therapeutic effect of adding trastuzumab (Herceptin) to chemotherapy in patients with HER2-positive disease.
NSABP B-18 and B-27 did not allow chest wall or regional nodal external radiation therapy after mastectomy. Although lumpectomy patients were required to have breast radiotherapy, they were not permitted to receive additional regional nodal radiotherapy. “To that extent, the two trials provide us with a large cohort of patients for whom the natural history of [locoregional recurrence] can be assessed without the confounding effects of nonuniform postmastectomy chest wall radiation or radiation to regional nodal basins,” the investigators stated.
Mamounas EP, et al: J Clin Oncol. October 1, 2012 (published early online).