Long-term outcome after neoadjuvant radiochemotherapy in locally advanced noninflammatory breast cancer and predictive factors for a pathologic complete remission : results of a multivariate analysis.

Background: An earlier published series of neoadjuvant radiochemotherapy (NRT-CHX) in locally advanced noninflammatory breast cancer (LABC) has now been updated with a follow-up of more than 15 years. Long-term outcome data and predictive factors for pathologic complete response (pCR) were analyzed.

Patients And Methods: During 1991-1998, 315 LABC patients (cT1-cT4/cN0-N1) were treated with NRT-CHX. Preoperative radiotherapy (RT) consisted of external beam radiation therapy (EBRT) of 50 Gy (5 × 2 Gy/week) to the breast and the supra-/infraclavicular lymph nodes combined with an electron boost in 214 cases afterwards or-in case of breast conservation-a 10-Gy interstitial boost with (192)Ir afterloading before EBRT. Chemotherapy was administered prior to RT in 192 patients, and concomitantly in 113; 10 patients received no chemotherapy. The update of all follow-up ended in November 2011. Age, tumor grade, nodal status, hormone receptor status, simultaneous vs. sequential CHX, and the time interval between end of RT and surgery were examined in multivariate terms with pCR and overall survival as end point.

Results: The total pCR rate after neoadjuvant RT-CHX reached 29.2%, with LABC breast conservation becoming possible in 50.8% of cases. In initially node-positive cases (cN+), a complete nodal response (pN0) after NRT-CHX was observed in 56% (89/159). The multivariate analysis revealed that a longer time interval to surgery increased the probability for a pCR (HR 1.17 [95% CI 1.05-1.31], p < 0.01). However, in large tumors (T3-T4) a significantly reduced pCR rate (HR 0.89 [95% CI 0.80-0.99], p = 0.03) was obtained. Importantly, pCR was the strongest prognostic factor for long-term survival (HR 0.28 [95% CI 0.19-0.56], p < 0.001).

Conclusion: pCR identifies patients with a significantly better prognosis for long-term survival. However, a long time interval to surgery (> 2 months) increases the probability of pCR after NRT-CHX.