Metaplastic Breast Carcinoma: Case Series and Review of the Literature

Metaplastic breast carcinoma (MpBC) is a rare disease entity of which it constitutes less than 1% of all breast carcinomas and first defined by Huvos et al. (Huvos et al., 1973; Tavassoli, 1992). MpBC is a heterogenous disease and includes squamous cell, spindle cell, matrixproducing,carcinosarcoma, osteoclastic giant cell metaplastic carcinoma, condroid differantiated metaplastic carcinoma and adenosquamous carcinoma subgroups (Wargotz et al., 1989a; 1989b; Wargotz, 1989a; 1990b; 1990c). Although pathogenesis and cell of origin of MpBC is still not completely clear, in some studies, it was claimed to be derived from myoepithelial origin (Tavassoli, 1992). In comparison to classical breast adenocarcinomas, tumor size is usually greater and the incidence of axillary lymph node involvement is less in MpBC cases (Chao et al., 1999; Beatty et al., 2006). Hormone and HER2 receptor positivity rates are also lower (0% to 26% for hormone receptors) in MpBC (Khan et al., 2003; Bae et al., 2011). The aim of this retrospective study was to evaluate MpBC patients to find out their clinical and pathological characteristics and also their treatment and probable survival difference.

In comparison to classical breast adenocarcinomas, tumor size is usually greater and the incidence of axillary lymph node involvement is less in MpBC cases (Chao et al., 1999;Beatty et al., 2006). Hormone and HER2 receptor positivity rates are also lower (0% to 26% for hormone receptors) in MpBC (Khan et al., 2003;Bae et al., 2011).
The aim of this retrospective study was to evaluate MpBC patients to find out their clinical and pathological characteristics and also their treatment and probable survival difference.

Materials and Methods
Between 2005 and 2011, 14 female MpBC patients admitted to Ankara Oncology Hospital, were evaluated, retrospectively. Patients' demographic characteristics, pathological characteristics of tumors, axillary lymph node involvement, metastatic sites, treatment schedules and survival data were evaluated using the medical records of patients.
Estrogen receptor (ER), and progesterone receptor (PR) positivity was defined as immunohistochemical staining with more than 1%. Positivity for HER-2 receptor was defined as strong complete membrane staining in more than 10% of tumor cells or positive with fluorescent in situ hybridization technique (FISH).
The response was evaluated by using the "Respond Evaluation Criteria in Solid Tumors". Progression free survival (PFS) was calculated from the date of diagnosis until disease progression. Overall survival (OS) was calculated from the date of diagnosis and death for any reason or the date of last contact.

Statistical Analysis
Descriptive statistics were performed to summarize the patients' characteristics. Comparison of the characteristics were analyzed by using analysis of variance (ANOVA) for means and Pearson chi-square-test for frequencies. The survival of the patients was estimated by using the Kaplan-Meier method. A p value less than 0.05 was considered to be statistically significant. For stastistical analysis, SPSS for Windows, version 15.0 software (SPSS Inc, Chicago, Illionis, USA) was used.
Modified radical mastectomy and axillary lymph node dissection was the surgery of choice in 11 patients. Axillary lymph nodes were involved in 64.3% (9/14) of the patients.
The most commonly involved distant metastatatic sites were lungs and brain (4 and 3 patients). Locally recurrent disease was rare and observed in only 1 patient. One patient was initially metastatic to the axillay lymph nodes and lungs at the time of diagnosis who was also considered as inoperable.
In 2 of 3 brain metastatic MpBC patients squamous component was evident. Chemotherapy was planned for adjuvant, neoadjuvant and palliative purposes in 9, 3 and 1 patient, respectively. None chemotherapy was performed for one patient. Salvage chemotherapy with capecitabine was chosen for 2 of 3 brain metastatic MpBC patients. Median cycles of chemotherapy was 6 (range:4-8).
Six of the progressed 7 MpBC patients received salvage chemotherapy. Two adenosquamous and squamous carcinoma MpBC patients had stable whereas 4 had progressive disease after a median 6 (range: 4-8) cycles of salvage chemotherapy.
Two patients of whom PR status is positive were given tamoxifen, and one patient with ER positive given anastrozole treatment.
During the follow up of a median 52 months (range: 7-71 months), progressive disease and death was seen in 7 and 5patients, respectively.
Patients with carcinosarcomas subtype have found a tendency of better survival although this was not statistically significant (median: 48 months, p:0.259) Median 3 year progression free survival (PFS) and overall survival (OS) in this patients group were 33% and 56% respectively (table 1 and table 2).

Discussion
The incidence of MpBC was approximately 0.2-0.3% in our breast cancer series. Although the median age of MpBC patients was over 50 years of age in the literature (Kaufman et al., 1984;Oberman et al.,1987;Rayson et al., 1999), the median age of our series was found to be about 5 years younger (45.5 years). Female preponderance is obvious but rarely male MpBC patients were reported in case series (Kuo et al., 2000).
MpBC is a heterogenous disease with different subgroups. Malignant epithelial (carcinoma) and malignant stromal (sarcoma) features can be found in MpBC spectrum. In our series, squamous and carcinosarcoma were found to be the most common histopathological subtypes. Sarcomatous types were reported to be as poor prognostic subtype compared to matrix producing subtype in some series (Wargotz and Norris,1989;Tseng et al., 2011). In contrast, we have found a tendency of better survival in carcinosarcoma subtype although this was not statistically significant.
In comparison to classical breast adenocarcinomas, tumor size is usually greater, hormone receptors are negative and incidence of axillary lymph node involvement is less for MpBC patients (Chao et al., 1999;Beatty et al., 2006;Bae et al., 2011). Median size of the tumor was reported to be in the range of 3.4-5.0 cm in some series (Oberman et al., 1987;Chao et al., 1999;Rayson et al., 1999;Luini et al., 2007) but in other series it was found to be larger up to 9 cm (Al Sayed et al., 2006). In our series, the median tumor diameter of MpBC cases was 5.7 cm (range: 2.0-8.0 cm), compatible with the English literature.
MpBC has a lesser tendency to involve axillary lymph nodes compared to adenocarcinoma and reported to be in the range of 0-53% in some series (Gersell et al., 1981;Bauer et al., 1984;Kaufman et al., 1984;Chao et al., 1999;Rayson et al., 1999;Al Sayed et al., 2006;Bae et al., 2011). Although lower incidence of axillary lymph node involvement, classical surgery techniques such as radical mastectomy and modified radical mastectomy including axillary dissection were the preferred surgery choices in the literature (Pitts et al., 1991;Gutman et al., 1995;Rayson et al., 1999) except for one study (Caceres et al., 2002). In our case series, axillary lymph node involvement was found to be higher (63.4 %) compared to English literature. This may be the reason of choosing more radical surgery techniques (breast conserving surgery was prefered for only 1 patient) for this cohort. Although a lesser tendency for axillary lymph node involvement and greater tumor diameter stage 4 disease at the time of diagnosis was not infrequently reported. Park et al reported an incidence 10.3% (Park et al., 2010) whereas others reported an incidence of 2.8-4.9% (Park et al., 2005;Son et al., 2006;Kim et al., 2007). In this case series, only 1 patient was presented with stage 4 disease (7.1%). Higher presentation with stage 4 disease may be explained by the limited number of patients and/or higher aggressiveness of the tumor.
MpBC is also usually presented as triple negative or basal-like breast cancer (Reis-Filho et al., 2006;Korsching et al., 2008). Lower ER, PR and HER-2 overexpression were reported in some studies (Bae et al., 2011;Lim et al., 2010;Toumi et al., 2011). Our results were similiar to these studies. Because of limited number of patients included in this study, our experience about the effect of hormonotherapies in MpBC was also limited. Rayson et al. gave tamoxifen to 4 hormone receptor positive MpBC patients upon recurrence but they reported none response at all (Rayson et al., 1999 ). However; Bae et al. gave hormonal therapy to three patients. No recurrence was observed during follow up period (Bae et al., 2011).
More than half of the MpBC patients developed local and distant metastasis during 5 years of follow-up. Lung and bone metastasis were found to be more frequent than lymphatic spreading, in many studies (Oberman et al., 1987;Wargotz and Norris,1989). This behaviour of MpBC resembles sarcomas. Luini et al. reported 3 locally recurrent and 8 lung and bone metastatic patients in their 37 MpBC series (Luini et al., 2007). Distant metastatic sites were mostly lungs and brain in the current study.
In routine clinical practice, there is no standard treatment regimen specific for MpBC or its subgroups, so clinical practice guidelines for invasive breast adenocarcinoma is mostly used instead (Carlson et al., 2009). In paralel to the literature, standard chemotherapy regimens for adenocarcinoma were given to the current study population. Interestingly, pathological complete response was seen in 2 of 3 patients who received neoadjuvant chemotherapy (67%) in the current study. Although it is recommended as the treatment approach in invasive breast cancer, there is limited knowledge about neoadjuvant chemotherapy use in MpBC in the literature (Luini et al., 2007). There is no defined subgroup in neoadjuvant studies and responses were not infrequently reported to be poor (Rayson et al., 1999).
Adjuvant chemotherapies are not also successful in case series in MpBC in the long-term (Al Sayed et al., 2006). Bae et al. reported no survival advantage of adjuvant chemotherapies in 42 of 47patients with MpBC (Bae et al., 2011). Another study confirmed the ineffectiviteness of adjuvant chemotherapy on diseasefree survival during 3 to 9 years of follow-up in MpBC (Chao et al., 1999). In contrast, Gutman et al found both disease-free and overall survival benefit with adjuvant chemotherapy in stage 1 and 2 MpBC patients (Gutman et al., 1995 [Chien T et al, 2010]. In another case series; patiens received liposomal doxorubicin and bevacuzimab but developed disease progression (Moulder et al., 2011). Alternative chemotherapy regimens might improve response and prognosis in MpBC subgroups.
The prognosis of MpBC is reported to be worse than breast adenocarcinoma (Sarah et al., 2012). The worse prognosis of MpBC can not only be explained by greater tumor size but also with histopathological tumor heterogeneity, higher proliferation index and poorer differentiation although less incidence of axillary lymph node involvement in comparison to breast adenocarcinomas. This may also be explained by frequent triple negative feature and lack of effectiveness of targeted therapies against this tumor.
Toumi et al. reported DFS and OS in MpBC were to be 42-84% and 64-83% respectively, during 5 years followup period (Toumi et al., 2011). In another study reported DFS and OS was found to be higher (81% and 93% respectively) in 5 years of follow-up (Park et al., 2010). However, Al Sayed et al. reported an event free survival and OS of 15% and 48%, respectively during 3 years of follow up (Al Sayed et al., 2006). In the current series, 3 year PFS and OS were 33% and 56%, respectively. Lower DFS and OS might partly be explained by higher involvement of axillary lymph nodes, aggressiveness of tumor pathologies and inclusion of limited number of MpBC patients.
MpBC is a rare disease entity and consists of different heterogenous subgroups. There is no specific treatment guidelines for MpBC and subgroup. Subgroup-specific and more courageous treatment approaches are required to improve survival rates. The addition of platinum to the chemotherapy regimen for squamous and triple negative subgroups, or high dose anthracycline regimen for sarcoma subgroup may be suitable alternatives. Since MpBC has a poor prognosis and aggressive nature, studies to evaluate different treatment alternatives for different subgroups may yield better treatment choices, in the future.