Impact of postmastectomy radiotherapy in T3N0 invasive carcinoma of the breast

Abstract

BACKGROUND. Randomized trials provide evidence for improved outcomes with postmastectomy radiotherapy (PMRT) in high‐risk patients. It has been suggested that patients with T3N0 breast cancer represent a favorable subgroup for which PMRT renders little benefit. In the current study, the authors used a United States population database to evaluate PMRT in this subgroup. METHODS. The cause‐specific survival (CSS) and overall survival (OS) of women with T3N0M0 breast cancer in the Surveillance, Epidemiology, and End Results database after mastectomy and axillary staging from 1988 to 2002 were analyzed. Univariate analysis was performed to relate CSS with PMRT (yes vs no), tumor size (≤7 cm vs >7 cm), grade (1 vs 2 or 3), patient age (≤50 years vs >50 years), the number of lymph nodes dissected (≤13 vs >13), and the era treated (1988‐1997 vs 1998‐2002). Multivariate analyses for CSS and OS were also performed. RESULTS. In total, 1865 women met the analysis criteria for OS; CSS data were available for 98.8% of those women. Of the women who were diagnosed during the era from 1988 to 1997, 22% received PMRT, and that rate increased to 41% during the era from 1998 to 2002. The actuarial 10‐year CSS for those who received PMRT versus those who did not receive PMRT was 81.6% versus 79.8%, respectively (P = .38). PMRT was not associated with a CSS benefit in any subgroup, a finding that persisted in multivariate analyses. Women who received PMRT had an increased 10‐year OS rate (70.7% vs 58.4%; P < .001) that was confined to women aged >50 years in a subgroup analysis. CONCLUSIONS. This retrospective, population‐based analysis demonstrated no increase in CSS with PMRT for women with T3N0 breast cancer, lending further support to the hypothesis that T3N0 disease postmastectomy represents a favorable subset of locally advanced breast cancer. Theincreased OS associated with PMRT in the absence of improved CSS likely reflects patient selection in this nonrandomized dataset. Prospective evaluation of PMRT in this population subset is warranted. Cancer 2008. © 2008 American Cancer Society.

Outcomes of Node-Negative Breast Cancer 5 Centimeters and Larger Treated With and Without Postmastectomy Radiotherapy

“…This is consistent with the SEER study of 1,865 women with pT3 >5 cm N0 disease, in which the BCSS rate was 80% in the PMRT cohort vs. 82% in the no-PMRT cohort (p = .4) (14). Furthermore, PMRT was not associated with a BCSS benefit in any subgroup on Abbreviations: BCSS = breast cancer-specific survival; HR = hazard ratio; CI = confidence interval; other abbreviations as in Table 1.…”

“…Using the Surveillance, Epidemiology, and End Results (SEER) database, Yu et al (13) and McCammon et al (14) studied cohorts of pT3 >5 cm N0 tumors treated with mastectomy, in which one-third of patients received PMRT. No significant difference in 10-year breast cancer-specific survival (BCSS) was found between the subgroups treated with or without PMRT (14).…”

“…No significant difference in 10-year breast cancer-specific survival (BCSS) was found between the subgroups treated with or without PMRT (14). However, SEER studies are limited by the absence of information regarding LRR outcomes, margin status, lymphovascular invasion (LVI), and systemic therapy use.…”

Postmastectomy radiation therapy in T3 node-negative breast cancer

“…Results demonstrated no difference in breast cancer-specific survival in all analyses (P > 0.05 for all). Our findings were corroborated by a prior analysis of the SEER database by McCammon et al [12], who published an analysis of PMRT in T3N0 patients from 1988e2002. A total of 1865 women were analyzed during the 1988e2002 study period, and it was noted that breast cancer-specific survival was not affected by radiation therapy use, with 10-y survival rates of 81.6% in those women who received PMRT and 79.8% in those who did not.…”

“…Given the large sample size accrued from 2000e2010 by Johnson et al, compared with the 1707 T3N0M0 patients we extracted from 2000e2009, there may have been a difference in selection criteria. Given that T3N0M0 breast cancer represents 1%e2% of all breast cancer, our sample size from 1988e2009 appears to be on trend with McCammon et al [12], who extracted 1865 women with T3N0M0 from 1988e2002.…”