Abstract P3-02-11: Clinical examination and breast MRI as predictors of pathologic complete response post neoadjuvant therapy in HER2 overexpressed subtypes and triple negative breast cancer

Abstract

Abstract Background: Preoperative identification of pathologic complete response (pCR) is important to decrease surgical morbity. The objective of this study was to determine diagnostic validity of clinical examination and magnetic resonance imaging (MRI) in determining pathologic response in patients with breast cancer subtypes HER 2 overexpressed and triple negative after neoadjuvant therapy. Methods: This is a cross- sectional study, with a sample comprising 72 patients woman with HER-2 overexpressed or triple negative breast submitted to neoadjuvant treatment at Hospital Sirio Libanês between January 2005 and December 2012. All patients were clinically evaluated by a group of seven breast surgeons. Double reading of breast MRI was performed in three periods: at the beginning of treatment, after the second cycle of chemotherapy and after treatment. Photographic record of the breast was done before and after chemotherapy. HER-2 and hormone receptors were assessed using immunohistochemistry. Sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (VNP) were estimated using pathology as the gold standard. Area under ROC curve and the corresponding 95% confidence intervals (95% CI) were calculated. Results: Thirty- two patients (44,4%) had triple negative tumors while 40 (55.6%) overexpressed HER-2. Among those with triple negative tumors, clinical examination evidenced a completed response in 31.2% (10/32) of the cases. pCR was observed in 3 patients (9.4%). Diagnostic validity measures for clinical examination were: Se= 100%, Sp=75.9%, PPV=42.9% and NPV=100%. In this group, MRI detected a complete response in 7 cases (21.9%). Therefore, MRI presented a Se=66.8%, Sp=82.8%, PPV 28.6% and NPV= 96%. Area under ROC curve was 0.88 (95% CI 0.80-0.96) and 0.75 (95% ci 0.41-1.00) for clinical examination and MRI, respectively. Among woman with tumors over expressing HER-2, complete response was observed through clinical examination in 45% (18/40) of these cases, showing Se= 100%, Sp=71%, PPV=100% and NPV=70,9%. In this group, complete radiological response was noted in 8 cases (20%). Therefor, MRI had Se=33.3%, Sp=83.9%, PPV 37.5% and NPV=96%. Area under ROC curve was 0.85 (95% CI 0.77-0.94) and 0.59 (95% CI 0.41-0.76) for clinical examination and MRI, respectively. Conclusions: Our findings demonstrate that clinical examination is superior to MRI to predict pCR for woman wth tumor overexpressing HER-2, while for tumor patients with triple negative tumors the two methods were equivalent. Therefore, clinical examination can be used with MRI to monitor tumor response to neoadjuvant chemotherapy and also to determine the best course of surgical action. Monitoring and assessment, however, are better when both methods are associates. Citation Format: Andrade FEM, De Barros ACS, Docema MF, Heinzen RN, De Andrade JZ, Nimir C, Mano MDS, Gianotti D, Ribeiro KDCB. Clinical examination and breast MRI as predictors of pathologic complete response post neoadjuvant therapy in HER2 overexpressed subtypes and triple negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-02-11.