By Faith Reidenbach
NEW YORK (Reuters Health) – For breast cancer patients who undergo neoadjuvant chemotherapy and mastectomy without radiation, the risk of local-regional recurrence (LRR) depends on both the clinical stage at presentation and the pathological extent of disease after chemotherapy, according to researchers at The University of Texas M. D. Anderson Cancer Center.
In the first-ever study of this issue, Dr. Thomas A. Buchholz and colleagues at the Houston center analyzed the outcomes of 150 such patients who had collectively participated in five prospective trials at their institution. Among survivors, the median followup period was 4.1 years.
The research team determined that LRR occurred in 35 patients (23%), including 12 patients in whom LRR developed simultaneously with distant metastases or subsequent to them. At both 5 and 10 years, the actuarial rate of LRR was calculated to be 27%, the team reports in the Journal of Clinical Oncology for January 1.
Eighteen patients achieved a pathologic complete response of both the primary tumor and lymph nodes. But even among this group, the 5-year LRR rate was 19%.
Multivariate analysis showed that the independent predictors of LRR were initial clinical stage IIIB or greater, pathologic involvement of four or more lymph nodes, and no use of tamoxifen, with hazard ratios of 4.5, 2.7, and 3.9, respectively.
"The only cohort of patients we identified to be at low risk for LRR were those patients with stage I/II disease who had clinically and pathologically negative lymph nodes," the Texas group states. "A number of other categories of patients, such as patients with one to three positive lymph nodes, carried intermediate risk for LRR."
When asked what he recommends for patients at intermediate risk of LRR, Dr. Buchholz said his group offers postmastectomy radiation to women with a "clinically relevant" risk.
"What that threshold should be is a judgment call," he told Reuters Health. "We acknowledge that radiation treatments carry some risks, albeit that with modern techniques we think the risk is much lower than in studies performed 2 to 3 decades ago. In general, we consider a risk of 15% to 20% to be clinically relevant."
"I reanalyzed some of these data [from the newly published study]," Dr. Buchholz added, "and specifically compared how the pathological factors affecting LRR differed in patients treated with chemotherapy before surgery compared to those treated with surgery before chemotherapy."
In the intermediate-risk group, he said, "if you had a tumor size 2 to 5 cm and one to three positive lymph nodes, you had a statistically greater LRR if you had neoadjuvant chemotherapy versus adjuvant chemotherapy. No difference was noted in those with 0 to 2 cm tumors and one to three positive lymph nodes."
Dr. Buchholz added that in a large US study, sponsored by the National Cancer Institute, intermediate-risk patients (those with 0 to 5 cm tumors and one to three positive lymph nodes) who have undergone mastectomy are currently being enrolled and are being randomized to receive or not receive postsurgical radiation.
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