| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Original Article |
1 Department of Surgery, Abington Memorial Hospital, 1200 Old York Road, Abington, Pennsylvania 19001, USA
2 American College of Surgeons, Commission on Cancer, 633 N. Saint Clair Street, Chicago, Illinois 60611, USA
3 Department of Surgery, University of Arkansas for Medical Sciences, 4301 West Markham, Little Rock, Arkansas 72205, USA
4 Department of Surgery, University of Alabama, 1530 Third Avenue South, Birmingham, Alabama 35294, USA
Correspondence: Address correspondence and reprint requests to: Christopher M. Pezzi, MD; E-mail: cpezzi{at}amh.org
| ABSTRACT |
|---|
|
|
|---|
Methods: Data from patients with MBC and IDC reported to the National Cancer Database from January 2001 through December 2003 were reviewed for year of diagnosis, patient age, race/ethnicity, tumor size, nodal status, American Joint Committee on Cancer (AJCC) stage, tumor grade, hormone receptor status, and initial treatment, and were analyzed statistically by the Pearson
2 test.
Results: A total of 892 patients with MBC and 255,164 patients with IDC were identified. The group with MBC was older (mean age, 61.1 vs. 59.7 years; P = .001), had a significantly increased proportion of African American (14.1%, 126 of 892, vs. 10.2%, 25,900 of 255,164; odds ratio [OR], 1.455, P = .001) and Hispanic patients (5.5%, 49 of 892 vs. 3.9%, 9,947 of 255,164; OR, 1.817, P = .001), had fewer T1 tumors (29.5% vs. 65.2%), more N0 tumors (78.1% vs. 65.7%, OR, .5, P = .001), more poorly or undifferentiated tumors (67.8% vs. 38.8%), and fewer estrogen receptorpositive tumors (11.3% vs. 74.1%, OR, 22.4, P = .001) than the IDC group. Patients with MBC were treated with breast-conserving surgery less frequently than patients with IDC (38.5% vs. 55.8%, OR, 2.0, P = .001) because of the larger tumor size. Chemotherapy was used more often for patients with MBC (53.4% vs. 42.1%, OR, 1.6, P = .001) because of more advanced AJCC stage.
Conclusions: MBC is a rare tumor with different characteristics than IDC: it presents with larger tumor size, less nodal involvement, higher tumor grade, and hormone receptor negativity. Patients with MBC are treated more aggressively than IDC (more often with mastectomy and chemotherapy) because of a higher stage at presentation, but are being treated by the same principles as IDC. Follow-up will determine the long-term results of the current treatment.
Key Words: Metaplastic Breast cancer
| INTRODUCTION |
|---|
|
|
|---|
Metaplastic breast cancer (MBC) is a rare malignancy characterized by various combinations of adenocarcinoma, mesenchymal, and other epithelial components. Because MBC was not officially recognized as a distinct pathologic diagnosis until 2000,1 knowledge about the patient demographics, presentation, tumor characteristics, and treatment patterns is limited. To date, only small series and case reports have attempted to delineate the factors that make MBC different from more common malignant breast histologies.217 We hypothesized that MBC has markedly different characteristics at presentation and is managed differently than infiltrating ductal carcinoma (IDC).
| MATERIALS AND METHODS |
|---|
|
|
|---|
Specific data examined included the year of diagnosis, patient age at diagnosis, race/ethnicity, primary tumor size, lymph node status, overall American Joint Committee on Cancer (AJCC) stage, tumor grade, and estrogen and progesterone receptor activity. Primary tumors with diffuse breast involvement or of unknown size, and patients who did not undergo surgery at the site of the primary tumor were not included in the analysis of primary tumor size. Also analyzed were the following: data concerning initial treatment, including surgery of the primary site, and the use of radiotherapy and/or chemotherapy; and information about the primary payer or type of medical insurance to provide insight concerning access to screening examinations, specifically mammography, of the study group. For comparison, the same data for all patients with a diagnosis of infiltrating ductal carcinoma (ICD-O-3 code 8500/3) for the same time period were also retrieved. The Pearson
2 test was used for statistical analysis. A value of P < .05 was considered statistically signifi-cant, and all P values are two-tailed.
| RESULTS |
|---|
|
|
|---|
|
The size of the primary tumor was reported in 807 patients (90.5%) with MBC and 228,501 patients (89.6%) with IDC who underwent surgery at the primary site. The size of the primary tumors was much larger for patients with MBC than for patients with IDC (Fig. 1
). Only 5.5% patients with MBC had tumors <10 mm in size (T1a or T1b) compared with 26.9% patients with IDC (OR, 6.3, P < .001). Most patients with MBC (70.5%) presented with tumors larger than 20 mm (T2 and above), whereas most patients with IDC (65.2%) presented with tumors smaller than 20 mm (OR, .7, P < .01). Tumors larger than 5 cm in size accounted for 20.4% of MBC, and only 5.2% of IDC.
|
|
|
Estrogen receptor (ER) and progesterone receptor (PR) testing was not performed on 3.0% of MBC specimens. It is unknown whether these tests had been performed or whether the results were unknown in 25.7% and 26.1% of cases, respectively. Of the cases in which ER testing was performed and the results were known, 72 (11.3%) of 636 patients with MBC were ER positive compared with 137,050 (74.1%) of 184,937 patients with IDC (OR, 22.4, P < .001). For PR testing, 66 (10.4%) of 632 patients with MBC were positive compared with 114,061 (62.4%) of 182,936 patients with IDC (OR, 14.2, P < .001).
Surgery was performed in 847 patients (95.0%) with MBC as part of their primary treatment and included a mastectomy in 471 (55.6%). Breast-conserving surgery (BCS) was performed in 373 patients (44.0%) with MBC. Three patients (.4%) underwent an unspecified surgical procedure. Of the 241,192 patients with IDC (94.5%) who underwent surgery as part of their primary treatment, mastectomy was performed in 92,424 patients (38.3%), and BCS was performed in 147,814 patients (61.3%). The more common use of BCS for IDC was statistically sig-nificant (OR, 2.0, P < .001). An unspecified surgical procedure was performed in 954 patients (.4%) in the IDC group. Surgery was used as the sole treatment modality for 263 patients (29.5%) in the MBC group and 58,639 patients (23%) in the IDC group, and was otherwise used in combination with radiotherapy, chemotherapy, and/or hormonal therapy. An analysis of the choice of surgical treatment by tumor size shows that for a given tumor size, the rates of BCS and mastectomy were similar for both patients with MBC and IDC (Fig. 3
).
|
Systemic chemotherapy was administered to 53.4% patients with MBC and was provided in addition to surgery (preoperatively or postoperatively) in all but 16 patients (3.4%). In comparison, 42.1% of patients with IDC were treated with systemic chemotherapy, again usually in addition to surgical treatment, in all but 4.1%. The increased use of chemotherapy for patients with MBC compared with those with IDC (53.4% vs. 42.1%, respectively) was statistically sig-nificant (OR, 1.6, P = .001). Hormonal therapy was provided in only 57 patients (6.4%) with MBC overall, compared with 83,485 patients (32.7%) with IDC. An analysis of treatment with systemic chemotherapy by AJCC stage (Fig. 4
) shows that chemotherapy was almost twice as likely to be administered to stage I patients with MBC compared with identically staged patients with IDC (39.7% vs. 21.7%), but that the percentage of stage II and III patients treated with chemotherapy was identical in both groups.
|
| DISCUSSION |
|---|
|
|
|---|
MBC is a rare breast malignancy accounting for only one-quarter of 1% of all breast malignancies reported to the NCDB during the study period. The increasing number of patients with MBC reported each year during the study period may represent an actual increase in incidence of the disease in the United States. However, it is likely that the increase seen in the number of cases is a result of increasing recognition of and familiarity with the diagnosis of MBC by both pathologists and the tumor registrars who assign and report codes to the NCDB. Since early reports more than 30 years ago,18,19 MBC has been increasingly recognized and reported as a distinct histologic type of breast cancer, but because of its rarity, only relatively small series have been reported. In the largest previous publications,812 Wargotz et al. separately described five subgroups of MBC, including matrix-producing carcinoma, spindle cell carcinoma, carcinosarcoma, squamous cell carcinoma of ductal origin, and metaplastic carcinoma with osteoclastic giant cells, with 26, 100, 70, 22, and 29 patients, respectively. Oberman16 reported 29 cases of MBC and concluded that the lack of a correlation of the microscopic pattern of these tumors with prognosis, as well as the presence of apparent overlapping microscopic findings, supported the concept that the subgroups described by Wargotz et al. are all variants of a single entity. There is still no strong consensus on this issue. Cytokeratin positivity in both the epithelial and mesenchymal components of MBC has led many to conclude that it is metaplasia of the epithelial elements of a carcinoma that gives these lesions their pseudosarcomatous appearance.17
With the recognition by ICD-O-3 of a specific code for MBC, cancer registries began collecting data from across the United States in 2001. The continued use of other overlapping or potentially related diagnoses, some more specific and some less so, is a confounding factor in the effort to study MBC. These additional diagnoses include squamous cell carcinoma, spindle cell carcinoma, carcinosarcoma, sarcoma not otherwise specified, pleomorphic carcinoma, spindle cell sarcoma, spindle cell squamous cell carcinoma, osteosarcoma, and others. Undoubtedly, some patients diagnosed with these alternatives would be considered by many pathologists to have MBC. We chose to limit our study only to the specific diagnosis of MBC for this analysis, to maximize the likelihood that our observations would be applicable to clinicians faced with a diagnosis of MBC in the future.
A difference was seen in the race/ethnicity of patients with MBC compared with IDC, with a higher percentage of patients identified as African American or Hispanic. The reasons for these differences are unknown, but represent a small but increased risk for MBC in these groups. The difference observed in the age of patients diagnosed with MBC compared with IDC, although statistically significant (mean age, 61.1 vs. 59.7 years, P = .001), is not likely of major clinical importance.
Patients with MBC had larger primary tumors than patients with IDC. This difference in size could possibly be explained by a difference in the use of screening mammography between the groups, or by a failure of screening examinations to identify MBC compared with IDC. With similar primary payor and types of medical insurance in both groups, it is unlikely that differences in access to or use of screening mammography alone can explain the large difference in size seen in this study. In addition, several reports13,14 have described the mammo-graphic and sonographic findings in MBC, including a round to ovoid, high-density mass with ill-defined or obscured margins and with architectural distortion. In one study, most patients presented with a rapidly growing palpable mass, which was then visible as a mammographic mass in 15 of 16 patients.13 These studies suggest that MBC is not mammographically occult.
It is most likely that the larger size at presentation for MBC is the result of a more rapid growth rate. Successful early detection of IDC by mammography depends on a relatively long, detectable, preclinical phase resulting from slower tumor growth, which may not exist with MBC. Most patients with MBC had poorly differentiated or undifferentiated tumors compared with IDC, which would also support this theory of more rapid growth for MBC.
The lower incidence of axillary lymph node involvement compared with IDC (21.9% vs. 34.3%) also represents an observed biological difference between these two tumors. The difference is even more dramatic when the larger tumor size of the patients with MBC is considered. If these tumors were biologically similar, we would expect a higher incidence of nodal involvement for patients with MBC on the basis of the larger tumor size. The presence of mes-enchymal components and sarcomatous elements seen in MBC may explain this different biologic behavior and pattern of metastasis. Wargotz et al.812 reported an incidence of axillary lymph node metastasis ranging from 6% to 26%, depending on the subtype of MBC, and was highest for carcinosar-coma. Additionally, for patients with carcinosar-coma, it was carcinoma that was the most frequent component to metastasize.
The higher AJCC stage seen in the MBC group, despite having more lymph nodenegative tumors, is strongly influenced by the larger tumor size. The 29.5% of patients with MBC having tumors <2 cm in size (T1), compared with 65.2% of patients with IDC with T1 tumors, explains the much higher incidence of AJCC stage I disease in patients with IDC, and AJCC stage II disease in patients with MBC.
The very low incidence of hormone receptor positivity in MBC compared with IDC represents another biologic difference in these tumors and has obvious implications for differences in their treatment. Hormonal therapy was rarely provided to patients with MBC, consistent with this low incidence of hormone receptor positivity in these patients. As would be suspected, the use of hormonal therapy in the patients in both groups in this study was directly related to the number of cases with hormone receptorpositive tumors.
The lack of hormonal therapy as a therapeutic option for adjuvant treatment, combined with an increased risk of systemic metastasis that would be predicted given the larger tumor size, higher AJCC stage, higher tumor grade, and hormone receptor negativity, explains the increased frequency of treatment with systemic chemotherapy in the patients with MBC. Data supporting the effectiveness of adjuvant chemotherapy for patients with MBC are lacking, and its use represents extrapolation from data related to more common histologic varieties of breast cancer. Given the apparent differences in tumor biology, the benefit of adjuvant chemotherapy, as well as the most effective drugs if it is to be administered, is unclear. Rayson et al.15 reported 27 patients over a 30-year period from the Mayo Clinic, 13 of whom (50%) developed distant metastasis. Ten different chemotherapy regimens were used to treat metastatic disease, and only one partial response was observed. They concluded that systemic therapy seems to be less effective.
Surgery was used to treat approximately 95% of both patients with MBC and IDC, but mastectomy was most common for patients with MBC (55.6%), whereas BCS was most common for patients with IDC (61.3%). This difference was related to the larger tumor size of the patients with MBC, including 20.4% of the MBC tumors >5 cm in size compared with only 5.2% for IDC tumors. When corrected for tumor size, the rates of BCS and mastectomy were similar between the two groups, suggesting that the principles of breast cancer surgery used for more common histologies are being applied to patients with MBC. The use of radiotherapy parallels the use of BCS, as would be anticipated. In both histologic groups, however, fewer patients received radiation than were treated with BCS. BCS was performed in 44.0% patients with MBC. The results of BCS and radiation in this group of patients with MBC, including ipsilateral breast recurrence rates, are being reported to the NCDB and will require further follow-up.
In summary, MBC is a very rare tumor and is different from IDC, with different presenting characteristics, demographics, and tumor biology. It is increasingly being reported to the NCDB since the ICD-O-3 codes have been implemented. Patients with MBC are more commonly African American or Hispanic and present with larger tumor size, less nodal involvement, higher AJCC stage, higher tumor grade, and hormone receptor negativity. Because of the larger tumor size and higher AJCC stage, patients with MBC are treated more aggressively than IDC, more often with mastectomy and systemic chemotherapy. In the absence of histology-specific data, patients are treated by use of the same principles that govern treatment of more common breast cancers. Follow-up is needed to determine the long-term results of the current treatment.
| APPENDIX 1 |
|---|
|
|
|---|
| FOOTNOTES |
|---|
Received for publication March 24, 2006. Accepted for publication June 26, 2006.
| REFERENCES |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
P. M. Carpenter, A. V. Dao, Z. S. Arain, M. K. Chang, H. P. Nguyen, S. Arain, J. Wang-Rodriguez, S.-Y. Kwon, and S. P. Wilczynski Motility Induction in Breast Carcinoma by Mammary Epithelial Laminin 332 (Laminin 5) Mol. Cancer Res., April 1, 2009; 7(4): 462 - 475. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Y. Bilimoria, A. K. Stewart, D. P. Winchester, and C. Y. Ko The National Cancer Data Base: A Powerful Initiative to Improve Cancer Care in the United States Ann. Surg. Oncol., March 1, 2008; 15(3): 683 - 690. [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |