Clifford A. Hudis, MD, Chief of the Breast Cancer Medicine Service at Memorial Sloan-Kettering Cancer Center, New York, commented after the presentation, “It strikes me that these findings are parallel to those shown with PAM50 by Liu et al at this meeting.” In that study,1 based on the Cancer and Leukemia Group B (CALGB) 9741 population, intrinsic molecular subtype did not predict for improved survival with dose-dense vs standard chemotherapy. The authors hypothesized that this is because the prognostic differences by subtype outweighed the modest but significant clinical benefit of dose-dense chemotherapy for the overall population.
Questions Remain
“The similarity relates to the fact that you have positive clinical trials, but you only have [tissue] from a subset, and though you see the same numerical trend, it is not statistically significant. This reflects the challenges inherent in planning studies retrospectively. The concern is that we could be missing a positive signal, just because of the statistics.”
Daniel F. Hayes, MD, the Stuart B. Padnos Professor in Breast Cancer Research at the University of Michigan, Ann Arbor, commented for The ASCO Post. “It is not clear what to make of these data. At the least, they are consistent with what we published from CALGB protocol 9344,2 in which paclitaxel was beneficial when added to [doxorubicin/cyclophosphamide] adjuvant chemotherapy in all groups except those with estrogen receptor–positive, HER2-negative cancers,” he told The ASCO Post. “However, there is still substantial confusion as to whether the biology of the cancer can predict response to all types of chemotherapy or specific types, such as paclitaxel.”
He said the data provide further impetus for clinicians to support Southwest Oncology Group (SWOG) S1007, in which node-positive patients with estrogen receptor–positive tumors and recurrence score < 25 will be randomly assigned to chemotherapy vs no chemotherapy; all will receive standard endocrine therapy. “This trial is open and we have nearly 1,000 patients already on the randomized part of the study,” Dr. Hayes noted. ■
Disclosure: Drs. Hudis and Hayes reported no potential conflicts of interest.
Reference
1. Liu MC, Pitcher BN, Mardis ER, et al: PAM50 gene signature is prognostic for breast cancer patients treated with adjuvant anthracycline and taxane-based chemotherapy. 2012 San Antonio Breast Cancer Symposium. Abstract P2-10-01. Presented December 5, 2012.
2. Henderson IC, Berry DA, Demetri GD, et al: Improved outcomes from adding sequential paclitaxel but not from escalating doxorubicin dose in an adjuvant chemotherapy regimen for patients with node-positive primary breast cancer. J Clin Oncol 21:976-983, 2003.
