Clinical characteristics of triple negative breast cancer in Egyptian women: a hospital-based experience

Purpose: Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with poor prognosis despite the high rates of response to chemotherapy. We aim to study the clinical features, factors influencing recurrence and survival outcomes of TNBC patients. Methods: We retrospectively studied the charts of patients with biopsy proven TNBC treated at The Clinical Oncology Department Ain-Shams University between 2009 and 2012. Results: One hundred and forty five patients fulfilled the eligibility criteria. The incidence of TNBC was 10.5% - 15% with a mean of 12% of all breast cancer patients. The follow-up duration ranged from six months to four years. The age range was 26 to 78 years. Infiltrating ductal carcinoma represented 93.1% of the pathologic types. 87% of patients were free of metastases (M0) at presentation. Clinical stages II and III represented 38 and 39.5% of the patients. 66% of patients had modified radical mastectomy. Following surgery, 77.5% of patients received adjuvant chemotherapy while 61% of the patients had adjuvant radiation therapy. Anthracyclines based chemotherapy was given to 52% of patients. Disease-free survival (DFS) of the M0 patients at 20 and 30 months was 92% and 80% respectively. Relapse occurred in 23% of M0 patients. After a mean duration of DFS of 15.1 months, the most common sites of metastases for relapsed M0 patients were pulmonary (44.8%), bone (41.4%), and locoregional (13.8%). The median overall survival (ORS) of patients was 18 months (1 - 45 months), whereas for the M1 group of patients the median ORS was 9 months (2 - 29 months). Conclusion: The incidence, pathological characteristics, and clinical behavior of TNBC were similar to what is mentioned in the literature. Adding taxanes to the chemotherapy protocols and using postoperative radiotherapy were both associated with a significant increase in the mean period of DFS, while did not significantly affect the ORS.


Introduction
Breast Cancer is still the most common malignancy in women worldwide, including Egypt (Cancer registry in Egypt). TNBC (Triple negative breast cancer) is frequently identified by conventional immunehistochemical techniques, as these tumors lack staining for the estrogen receptor (ER), progesterone receptor (PR), and the human epidermal growth factor (HER2). 1 The St. Gallen international expert consensus 2011 proposed a new classification system for breast cancer based on its division into five subgroups, namely; normal-like, basal, luminal A&B and HER-2 enriched. A Claudin-low subtype is another described molecular subtype referring to tumors showing features of mesenchymal and mammary stem cells. 2 The criteria to identify subtypes were further recently refined at the 2013 conference, in that moderate or a strong expression of PR and Ki -67 level were both recognized as being important to the surrogate definition of a "Luminal A-like" disease. According to these criteria, the subtypes in question have been defined as: Luminal A -ER positive, HER2 negative, Ki -67 low, and PR high; Luminal B (HER2 negative) -ER positive, HER2 negative, and either Ki -67 high or PR low; Luminal B-like (HER2 positive) -ER positive, HER2 over expressed or amplified, any Ki -67, and any PR; HER2

Introduction
Breast Cancer is still the most common malignancy in women worldwide, including Egypt (Cancer registry in Egypt). TNBC (Triple negative breast cancer) is frequently identified by conventional immunehistochemical techniques, as these tumors lack staining for the estrogen receptor (ER), progesterone receptor (PR), and the human epidermal growth factor (HER2). 1 The St. Gallen international expert consensus 2011 proposed a new classification system for breast cancer based on its division into five subgroups, namely; normal-like, basal, luminal A&B and HER-2 enriched. A Claudin-low subtype is another described molecular subtype referring to tumors showing features of mesenchymal and mammary stem cells. 2 The criteria to identify subtypes were further recently refined at the 2013 conference, in that moderate or a strong expression of PR and Ki -67 level were both recognized as being important to the surrogate definition of a "Luminal A-like" disease. According to these criteria, the subtypes in question have been defined as: Luminal A -ER positive, HER2 negative, Ki -67 low, and PR high; Luminal B (HER2 negative) -ER positive, HER2 negative, and either Ki -67 high or PR low; Luminal B-like (HER2 positive) -ER positive, HER2 over expressed or amplified, any Ki -67, and any PR; HER2

Introduction
Breast Cancer is still the most common malignancy in women worldwide, including Egypt (Cancer registry in Egypt). TNBC (Triple negative breast cancer) is frequently identified by conventional immunehistochemical techniques, as these tumors lack staining for the estrogen receptor (ER), progesterone receptor (PR), and the human epidermal growth factor (HER2). 1 The St. Gallen international expert consensus 2011 proposed a new classification system for breast cancer based on its division into five subgroups, namely; normal-like, basal, luminal A&B and HER-2 enriched. A Claudin-low subtype is another described molecular subtype referring to tumors showing features of mesenchymal and mammary stem cells. 2 The criteria to identify subtypes were further recently refined at the 2013 conference, in that moderate or a strong expression of PR and Ki -67 level were both recognized as being important to the surrogate definition of a "Luminal A-like" disease. According to these criteria, the subtypes in question have been defined as: Luminal A -ER positive, HER2 negative, Ki -67 low, and PR high; Luminal B (HER2 negative) -ER positive, HER2 negative, and either Ki -67 high or PR low; Luminal B-like (HER2 positive) -ER positive, HER2 over expressed or amplified, any Ki -67, and any PR; HER2 positive -HER2 over -expressed or amplified, ER and PR absent; and triple negative -ER and PR absent and HER2 negative. 3 TNBC patients have a higher risk of metastases and poor overall survival because TNBC is found to be correlated with mutations of BRCA1 gene, over expression of oncoytogenic kinases such as human epidermal growth factor receptor 2, vascular endothelial growth factor -A, insulin-like growth factor -1 (IGF -1) / IGF receptor and transforming growth factor -B1. 4 These molecular features may have implications for chemotherapy sensitivity to platinum and other directly DNAdamaging agents. Using gene expression analysis, Lehmann et al identified six TNBC subtypes namely; basal -like (BL1 & BL20), an immunomodulatory (IM), a mesenchymal (M), a mesenchymal stem -like (MSL) and a luminal androgen receptor (LAR) subtype. 5 TNBC is a clinically challenging subtype which accounts for about 9-21% of all breast cancers, including patients with stages, I -IV. 6 Compared to other types of breast cancer, TNBC is associated with poor prognosis and overall survival. 1, 7, 8 TNBC patients tend to be of younger age less than 50 years. 1, 9 TNBC tumors have a shorter median time to relapse and death. TNBC is often locally advanced and of high grade. 1 The patients have increased risk of local recurrence and metastases, mainly in the lung, brain and soft tissue. 10,11,7,8 TNBC is more chemosensitive, and have higher rates of pathological complete remission following neoadjuvant chemotherapy than in other breast cancer types. 8 The adjuvant chemotherapy is usually recommended in TNBC and should include anthracyclines, taxanes and an alkylating agent. 12 On the other hand TNBC lacks targeted therapies, and patients do not benefit from anti -estrogen hormonal therapy or trastuzumab. 1 The aim of this retrospective analysis is to study the clinical characteristics, the prognostic factors of recurrence, disease free survival and overall survival in Egyptian TNBC patients treated at the Department of Clinical Oncology, Ain-Shams University.

Methods and Materials
We analyzed the institutional medical records, and identified patients who were histopathologically diagnosed with triple negative breast cancer and underwent primary treatment at The Clinical Oncology Department Ain -Shams University between 2009 and 2012. After obtaining approval from the Institutional Review Board at Ain -Shams University Hospitals, a retrospective chart review of patients' demographics, clinical and pathological data was performed. Treatment, follow-up and survival data were obtained from the patients' records. One hundred and forty five patients fulfilled the eligibility criteria which are 18 years or older, immunohistochemistry (IHC) negative expression of ER and PR, and negative HER -2 neu expression or HER -2 neu 1+ or 2+ expression on IHC accompanied by a negative fluorescence in situ hybridization (FISH) result.

Statistical analysis
Data were revised, coded, tabulated and analyzed using the Statistical Software Package for the Social Sciences, for Windows version 18.0 (SPSS / PASW, Inc., 2009, Chicago, IL). Descriptive statistics (mean and standard deviation) were used to evaluate the DFS of the nonmetastatic group of patients, and to evaluate the ORS of both metastatic and non-metastatic groups. Chi-square tests were used to assess differences between the DFS and ORS using categorical variables. The overall survival time was calculated in months from the date of diagnosis based on breast biopsy to the date of death or last follow-up. The DFS in months was calculated from the end of the primary treatment until the last date the patient survived without symptoms or signs. Univariate Kaplan -Meier survival curves were plotted, and the log -rank test was used to determine if differences were statistically significant. Statistical significance was defined as alpha less than 0.05.

Results
We studied 145 out of the 154 patients diagnosed with TNBC who presented to our department over fouryears period where 9 patients had incomplete data in their charts ( Table 1). The mean age at diagnosis was 52 years. A positive family history was detected in (7.6%) 11 / 145 of TNBC patients (  The DFS for the M0 patients (126) at 20 and 30 months was about 92% and 80% respectively ( Figure 1). After a mean period of disease -free survival (DFS) of 15.1 months, 29 patients out of 126 (23%) relapsed. The most common sites of relapse were the lung (13 patients, 44.8%), bone (12 patients, 41.4%), and locoregional (4 patients, 13.8%) ( Table 8). The overall survival of both M0 and M1 patients at 20 months and 30 months was about 98% and 88% respectively ( Figure  2). The median ORS for the M0 group of patients was 18 months (1 -45 months), whereas for the M1 group of patients the median ORS was 9 months (2 -29 months) ( Table 5).
Except for tumor stage which had direct effect on the recurrence and overall survival (P < 0.05), univariate analysis showed that all other risk factors had no statistically significant relationship to either recurrence or overall survival (Tables 6, 7). Patients with stages 0 and I had no recurrence compared to patients with advanced stages. Similarly, the overall survival of patients with early stages was better than with advanced stages as shown in Table (5). The disease stage, the type of chemotherapy and the adjuvant radiation therapy had direct statistically significant effect on the DFS (P < 0.05) ( Table 6).  The DFS for the M0 patients (126) at 20 and 30 months was about 92% and 80% respectively ( Figure 1). After a mean period of disease -free survival (DFS) of 15.1 months, 29 patients out of 126 (23%) relapsed. The most common sites of relapse were the lung (13 patients, 44.8%), bone (12 patients, 41.4%), and locoregional (4 patients, 13.8%) ( Table 8). The overall survival of both M0 and M1 patients at 20 months and 30 months was about 98% and 88% respectively ( Figure  2). The median ORS for the M0 group of patients was 18 months (1 -45 months), whereas for the M1 group of patients the median ORS was 9 months (2 -29 months) ( Table 5).
Except for tumor stage which had direct effect on the recurrence and overall survival (P < 0.05), univariate analysis showed that all other risk factors had no statistically significant relationship to either recurrence or overall survival (Tables 6, 7). Patients with stages 0 and I had no recurrence compared to patients with advanced stages. Similarly, the overall survival of patients with early stages was better than with advanced stages as shown in Table (5). The disease stage, the type of chemotherapy and the adjuvant radiation therapy had direct statistically significant effect on the DFS (P < 0.05) ( Table 6).   Figure  2). The median ORS for the M0 group of patients was 18 months (1 -45 months), whereas for the M1 group of patients the median ORS was 9 months (2 -29 months) ( Table 5).
Except for tumor stage which had direct effect on the recurrence and overall survival (P < 0.05), univariate analysis showed that all other risk factors had no statistically significant relationship to either recurrence or overall survival (Tables 6, 7). Patients with stages 0 and I had no recurrence compared to patients with advanced stages. Similarly, the overall survival of patients with early stages was better than with advanced stages as shown in Table ( 5). The disease stage, the type of chemotherapy and the adjuvant radiation therapy had direct statistically significant effect on the DFS (P < 0.05) ( Table 6).

Discussion
The current study is a retrospective review of 145 patients with TNBC in our institution over a 4-year period (2009 -2012). It is one of the few studies of TNBC in non -Western countries. In our study, the rate of TNBC was 12%, which is comparable to other studies (9 -21%) in non -Western countries 10, 13, 14 , and in Western countries. 15, 11,6,16 Triple -negative breast tumors have been characterized by several aggressive clinicopathologic features including onset at younger age, higher mean tumor size, higher-grade tumors, and, in some cases, a higher rate of node positivity. 1, 17 The mean age at diagnosis in this study is 52 years, similar to the mean age at presentation documented by many studies.

Discussion
The current study is a retrospective review of 145 patients with TNBC in our institution over a 4-year period (2009 -2012). It is one of the few studies of TNBC in non -Western countries. In our study, the rate of TNBC was 12%, which is comparable to other studies (9 -21%) in non -Western countries 10, 13, 14 , and in Western countries. 15, 11,6,16 Triple -negative breast tumors have been characterized by several aggressive clinicopathologic features including onset at younger age, higher mean tumor size, higher-grade tumors, and, in some cases, a higher rate of node positivity. 1, 17 The mean age at diagnosis in this study is 52 years, similar to the mean age at presentation documented by many studies. 18

Discussion
The current study is a retrospective review of 145 patients with TNBC in our institution over a 4-year period (2009 -2012). It is one of the few studies of TNBC in non -Western countries. In our study, the rate of TNBC was 12%, which is comparable to other studies (9 -21%) in non -Western countries 10, 13, 14 , and in Western countries. 15, 11,6,16 Triple -negative breast tumors have been characterized by several aggressive clinicopathologic features including onset at younger age, higher mean tumor size, higher-grade tumors, and, in some cases, a higher rate of node positivity. 1, 17 The mean age at diagnosis in this study is 52 years, similar to the mean age at presentation documented by many studies.  33 In the current study, positive lymph node was 66% possibly due to the tendency to late presentation of patients in the social stratum that we treat at our center.
Despite the poor clinical outcome and DFS, the more aggressive clinical course in the metastatic setting, TNBC is sensitive to standard chemotherapy. Chemotherapy is the standard treatment of TNBC in the adjuvant, neoadjuvant, and metastatic settings due to the lack of response to traditional hormonal therapies and targeted therapies. 1 TNBC patients have a higher pathologic complete response (pCR) than non -TNBC, and also better survival compared to TNBC patients who do not achieve pCR. 8 The pCR rate was 29% in patients who received neoadjuvant anthracyclines based chemotherapy and 38% after anthracyclines and taxanes combined treatment. 46    The role of cetuximab; an anti -EFGR monoclonal antibody in patients with metastatic TNBC was studied 59 by comparing cetuximab plus cisplatin versus cisplatin alone. The authors demonstrated an overall better response rate of 20% when compared to a 10% overall better response rate with cisplatin alone. Cisplatin plus cetuximab also resulted in longer progression free survival (PFS) compared with cisplatin alone (median, 3.7 vs. 1.5 months) with a corresponding median OS of 12.9 versus 9.4 months. Common grade 3 / 4 adverse events included acne -like rash, neutropenia, and fatigue. Despite the longer PFS and OS, the trial failed to reach its primary endpoint, which is the overall response rate compared to the single regimen. Additionally cetuximab induced diarrhea was a concern when added to chemotherapy as carboplatin and irinotecan despite an increased overall response rate in the TNBC subset of O'Shaughnessy's phase II trial. 60 The potential efficacy of anti -EGFR strategies needs further investigation with more trials.

Conclusion
This study documents the clinical experience of TNBC at our institution. The results of the study accord with the literature data of characteristics of TNBC in terms of young age at presentation, high -grade tumors, late stages at diagnosis, and short disease -free survival. We acknowledge the limitations of this study inherent to most retrospective studies, the relatively small sample size, and the lack of BRCA gene mutations' studies due to the limited financial resources. However, our results are unique to Egypt, are one of the very few studies of TNBC in the Middle East, and represent a single -institution approach to patient care.
Tumor stage, chemotherapy type and adjuvant radiation therapy statistically influenced the recurrence and the duration of disease -free survival. In addition, the tumor stage statistically influenced the overall survival of both the metastatic and non -metastatic TNBC in our study.
Unfortunately, TNBC as an aggressive subtype of breast cancer has limited treatment options when it does not respond to or progresses after the standard and /or taxanes based regimens. More research should be directed at identifying molecules and pathways that may be effective targets for new drugs.