Solin, L.J.

523 Background: Adjuvant trastuzumab (Herceptin [H]) with chemotherapy improves outcome in HER2+ breast cancer (BC). Preclinical studies suggest H may enhance RT. We herein assess if H given with adjuvant RT increases adverse events (AE) after breast conserving surgery or mastectomy. Methods: N9831 randomized 3505 women with pT1–3N1–2M0, pT2–3N0M0, or pT1cN0M0 (ER/PR negative) HER2+ BC to doxorubicin (A) and cyclophosphamide (C) followed by weekly paclitaxel (T), AC→T→H, or AC→TH→H. Post-lumpectomy breast ± nodal RT was recommended, as was post-mastectomy chest wall + nodal RT (>3 nodes +); internal mammary RT was prohibited. RT started within 5 weeks of completion of T and allowed concurrently with H. 2324 eligible patients were enrolled on study prior to April 25, 2004: 1460 patients receiving RT are available for analysis of RT-associated AEs. Also, 1286 patients on +H arms who completed T (908 +RT and 378 -RT) are available for analysis of clinical cardiac events (CE). Rates of RT-associated AEs were compared across treatment arms, and rates of CE were compared for +RT vs -RT patients within +H arms. All reported p-values are for chi-squared statistics. Results: With a median follow-up of 1.5 years, significant differences among arms in RT-associated AEs were not identified. No significant differences across arms in +RT patients existed in the incidence of skin reaction (p=0.78), pneumonitis (p=0.78), dyspnea (p=0.87), cough (p=0.54), esophageal dysphagia (p=0.26), or neutropenia (p=0.16). There was a significant difference in +RT patients in the incidence of leukopenia (p=0.02) with higher incidence rates in the arms receiving H. RT did not increase the frequency of CE. In the AC→T→H arm, the incidence of CE was 2.2% in +RT patients versus 2.9% in -RT patients. In the AC→TH→H arm, the incidence of CE was 1.5% in +RT patients versus 6.3% in -RT patients. No difference in CE was seen between left- and right-sided RT fields in +RT patients in either +H arm. Conclusion: Concurrent administration of adjuvant RT with H in early stage breast cancer patients is not associated with an increased incidence of acute RT AEs. Further follow-up is required to assess late AEs. No significant financial relationships to disclose.

Abstract Background: We have previously reported the results of surgical excision without irradiation for selected patients with DCIS in ECOG E5194, where the 5-year rates of local recurrence varied with age, grade, and lesion size (Hughes et al. J Clin Oncol 27:5319, 2009). New methods are needed to provide more accurate and reproducible assessment of recurrence risk. Methods: ECOG E5194 included 670 eligible patients with DCIS treated with surgical excision (≥ 3 mm negative margins) without irradiation, 228 of whom received tamoxifen. Patients had low or intermediate grade DCIS ≤ 2.5 cm, or high grade DCIS ≤ 1 cm. The Oncotype DX® assay was performed by quantitative RT-PCR using formalin fixed paraffin embedded tumor specimens from 327 patients (49% of the parent study). Recurrence Score® (RS) was calculated using the published algorithm. A new, prespecified DCIS Score™ was designed to predict recurrence using an optimized gene expression algorithm. The primary objective was to determine whether there was a significant association between the risk of an ipsilateral breast event (IBE) and the continuous DCIS Score in Cox models. 46 patients had an IBE (defined as ipsilateral local recurrence of DCIS [n=20] or invasive cancer [n=26]). Median follow-up was 8.8 years. Results: The 10-year IBE rates were 15.4% for low/intermediate grade DCIS and 15.1% for high-grade DCIS (as determined by central pathology review), and for invasive IBE, 5.6% and 9.8%, respectively. Comparison between local and expert grading showed substantial disagreement. Continuous DCIS Score was significantly associated with IBE (HR 2.34 per 50 units; 95% CI 1.15, 4.59; p=0.02) when adjusted for tamoxifen use (prespecified primary analysis) and with invasive IBE (HR 3.73; CI 1.34, 9.82; p=0.01). DCIS Score was significantly associated with outcome when evaluated by the prespecified risk groups (see Table). Similar results were observed with and without adjustment for tamoxifen use or for negative margin width. Features associated with IBE in multivariate models included menopausal status (HR 0.49; 95% CI 0.27, 0.90; p=0.02), tumor size (HR 1.52 per 5 mm; 95% CI 1.11, 2.01; p=0.01), and continuous DCIS Score (HR 2.41; 95% CI 1.15, 4.89; p=0.02). The standard RS, which is calculated using thresholding of many genes unlike the DCIS Score, was not associated with IBE or invasive IBE (p > 0.6). Conclusions: We have prospectively validated a multigene assay that quantifies recurrence risk and complements traditional clinical and pathologic factors in selected patients with DCIS treated with surgical excision without irradiation. The DCIS Score provides a new clinical tool for individualized selection of treatment for patients with DCIS. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr S4-6.

Abstract Background: Trastuzumab (H) improves disease-free survival (DFS) in patients (pts) with HER2 positive breast cancer (BR Ca) when used with adjuvant chemotherapy. We herein compare the rates of local regional recurrence (LRR) in pts randomized to adjuvant chemotherapy with or without adjuvant H. Methods: The phase 3 randomized trial NCCTG N9831 enrolled 3505 pts with high risk HER2 positive Br Ca to evaluate the effect of adjuvant H on DFS. Pts were randomized to either doxorubicin (A) and cyclophosphamide (C) followed by paclitaxel (T); or AC→TH→H. RT was given concurrently with H after ACT chemotherapy. Pts analyzed underwent lumpectomy (L) + radiotherapy (RT), mastectomy (M) alone, or M+RT. All pts underwent sentinel lymph node biopsy alone and/or axillary dissection. 2816 pts were eligible for competing risk analysis of LRR as a first event (competing risks were distant recurrence, contralateral Br Ca, second primary cancer, or death). Median follow-up is 5.3 years. Results: Primary breast therapy included L+RT 1062 (38%), M 711 (25%), and M+RT 1043 (37%). Axillary dissection was performed in 90% of pts but less frequently with L+RT (83%) compared to M (88%) or M+RT (98%), chi-sq P<0.001. Stage at presentation was I 41%, II 51%, and III 8% with a significant greater proportion of higher stage pts undergoing M+RT, chi-sq P<0.001. Overall the 5-year LRR rate was 4.1% (95% CI 3.5-4.9%) and similar among the treatment groups: L+RT 4.7% (95% CI 3.6-6.1%), M 3.5% (95% CI 2.4-5.1%), and M+RT 2.3% (95% CI 1.6-3.4%). Among pts with a LRR, 66% were local recurrence only, 11% were local-regional, and 23% were regional only. In the L+RT patients with a LRR, the corresponding rates were 74%, 7%, and 19%, respectively. In the M patients with a LRR, the corresponding rates were 40%, 23%, and 37%, respectively. In the M+RT patients with LRR, the rates were 79%, 4%, and 17%, respectively. H is associated with a non-statistically significant reduction in the risk of LRR for pts who receive L+RT or M+RT (Table 1). No such trend was seen in the M alone group but the number of events was low. Table 1. LRR According to Local and Adjuvant Treatment Groups Conclusion: The LRR as the first reported site of failure was low with a median 5. 3 year follow-up. Adjuvant H was associated with a trend of lower LRR in the pts treated with L + RT or M+RT. This observation suggests an additive effect of RT and H on LRR that warrants further investigation. The small number of local-regional events in this one randomized trial supports further investigation of LRR across other adjuvant trastuzumab trials. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-13-02.