Metaplastic carcinoma

Last updated December 26, 2023

Metaplastic carcinoma, otherwise known as metaplastic breast cancer (MBC), is a heterogeneous group of cancers that exhibit varied patterns of metaplasia and differentiation along multiple cell lines. This rare and aggressive form of breast cancer is characterized as being composed of a mixed group of neoplasms containing both glandular and non-glandular patterns with epithelial and/or mesenchymal components. It accounts for fewer than 1% of all breast cancer diagnoses.^[1] It is most closely associated with invasive ductal carcinoma of no special type (IDC), and shares similar treatment approaches.^[2] Relative to IDC, MCB generally has higher histological grade and larger tumor size at time of diagnosis, with a lower incidence of axillary lymph node involvement. MCB tumors are typically estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor-2 (HER-2) negative, meaning hormone therapy is generally not an effective treatment option, which correlates to a relatively poor prognosis. MCB was first recognized as a distinct pathological entity in 2000 by the World Health Organization.^[1]

Classification

Owing to its relatively recent pathological distinction, multiple classification systems have been adopted for MCB among different organizations and research groups. The World Health Organization classifies MCB under two categories: epithelial-type and mixed-type. The epithelial-type is further classified as squamous cell carcinoma, adenocarcinoma with spindle cell differentiation, and adenosquamous carcinoma. The mixed-type is further classified as carcinoma with chondroid metaplasia, carcinoma with osseous metaplasia, and carcinosarcoma. Wargotz et al. proposed a classification system for MCB according to its cytopathological features. These classifications are spindle cell, squamous cells, matrix-producing, carcinosarcoma, and MCB with osteoclastic giant cell. Another research group, Oberman et al., proposed a classification system consisting of spindle cell carcinoma, invasive ductal carcinoma with extensive squamous metaplasia, and invasive ductal carcinoma with pseudosarcomatous metaplasia. The lack of consensus between these various classification systems for MCB has led to complications in both clinical practice and research studies.^[1]

Risk factors

In most MCB cases, patients are women over the age of 50, indicating that age is a major factor in determining the risk of developing MCB. Genetics are another primary risk factor for developing MCB. Genetic mutations and family history both correlate to higher risk.^[3]

Signs and symptoms

The most commonly presenting symptom of MCB is a rapidly growing, palpable mass of the breast. If the tumor has metastasized, more severe symptoms will be presented, depending on the site of metastasis.^[3]

Diagnosis

Mammography is a standard diagnostic tool for MCB, where the tumors will typically display as a high-density mass. However, they can also mimic IDCs as well as benign lesions in the mammogram. Sonography is also often used to help diagnose MCB, where solid and cystic components may be observed. This is related to necrosis and cystic degeneration. In fine-needle aspiration (FNA) smears, only 57% of cases show ductal carcinoma and metaplastic components. Consequently, roughly half of MCB tumors cannot be diagnosed by FNA. Pathologic tissue diagnosis is therefore essential to distinguish MCB from other breast cancers in order to institute proper and prompt treatment. This is achieved using immunohistochemistry with a cytokeratin panel to distinguish such cases from phyllodes tumors, primary sarcomas, and fibromatoses.^[3]

Prognosis

The prognosis of MCB can vary between different sub-classifications, which, given the heterogeneity of classification systems, makes assigning prognoses difficult. However, the prognosis for MCB is generally poor. Predictors associated with worse prognosis of MCB include age younger than 39 years at presentation, tumor invasion of the skin, and squamous cell carcinoma spread to the lymph nodes. The 5-year survival rate for MCB varies by classification, and ranges from 49% in the most deadly classifications to 64%.^[3]

Treatment

Despite the range of classifications of MCB, treatment options are standard with other breast cancers. If the tumor is diagnosed early, breast-saving surgery could be an option, although this is relatively uncommon. In non-metastatic MCB, the most common treatment is mastectomy. If the tumor is metastatic, surgery is no longer a viable option, and treatment generally defaults to aggressive chemotherapy. Because MCB tumors are typically triple-negative, hormone therapy is not usually an option for treatment. This is directly related to its relatively poor prognosis.^[3]

Related Research Articles

Thyroid neoplasm is a neoplasm or tumor of the thyroid. It can be a benign tumor such as thyroid adenoma, or it can be a malignant neoplasm, such as papillary, follicular, medullary or anaplastic thyroid cancer. Most patients are 25 to 65 years of age when first diagnosed; women are more affected than men. The estimated number of new cases of thyroid cancer in the United States in 2010 is 44,670 compared to only 1,690 deaths. Of all thyroid nodules discovered, only about 5 percent are cancerous, and under 3 percent of those result in fatalities.

Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, are metastases (mets). It is generally distinguished from cancer invasion, which is the direct extension and penetration by cancer cells into neighboring tissues.

Carcinoma is a malignancy that develops from epithelial cells. Specifically, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that arises from cells originating in the endodermal, mesodermal or ectodermal germ layer during embryogenesis.

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Tubular carcinoma is a subtype of invasive ductal carcinoma of the breast. More rarely, tubular carcinomas may arise in the pancreas or kidney. Most tubular carcinomas begin in the milk duct of the breast and spread to healthy tissue around it.

Papillary carcinomas of the breast (PCB), also termed malignant papillary carcinomas of the breast, are rare forms of the breast cancers. The World Health Organization (2019) classified papillary neoplasms of the breast into 5 types: intraductal papilloma, papillary ductal carcinoma in situ (PDCIS), encapsulated papillary carcinoma (EPC), solid-papillary carcinoma (SPC), and invasive papillary carcinoma (IPC). The latter four carcinomas are considered here; intraductal papilloma is a benign neoplasm. The World Health Organization regarded solid papillary carcinoma as having two subtypes: in situ and invasive SPC.

Ovarian squamous cell carcinoma (oSCC) or squamous ovarian carcinoma (SOC) is a rare tumor that accounts for 1% of ovarian cancers. Included in the World Health Organization's classification of ovarian cancer, it mainly affects women above 45 years of age. Survival depends on how advanced the disease is and how different or similar the individual cancer cells are.

References

1 2 3 Böler DE, Kara H, Sağlıcan Y, Tokat F, Uras C (2016-08-01). "Metaplastic carcinoma of the breast: A case series and review of the literature". Journal of Oncological Sciences. 2 (2–3): 38–42. doi: 10.1016/j.jons.2016.08.006 .
↑ "Metaplastic Breast Cancer". Johns Hopkins Medicine. Johns Hopkins University. 2015-04-22. Archived from the original on 2015-02-15. Retrieved 2015-04-22.
1 2 3 4 5 Luini, Alberto; Aguilar, Marisel; Gatti, Giovanna; Fasani, Roberta; Botteri, Edoardo; Brito, Jack Antonio Diaz; Maisonneuve, Patrick; Vento, Anna Rita; Viale, Giuseppe (2007-01-23). "Metaplastic carcinoma of the breast, an unusual disease with worse prognosis: the experience of the European Institute of Oncology and review of the literature". Breast Cancer Research and Treatment. 101 (3): 349–353. doi:10.1007/s10549-006-9301-1. ISSN 0167-6806.

This article incorporates public domain material from Dictionary of Cancer Terms. U.S. National Cancer Institute.

External links

Metaplastic carcinoma entry in the public domain NCI Dictionary of Cancer Terms

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[Boler-1] 1 2 3 Böler DE, Kara H, Sağlıcan Y, Tokat F, Uras C (2016-08-01). "Metaplastic carcinoma of the breast: A case series and review of the literature". Journal of Oncological Sciences. 2 (2–3): 38–42. doi: 10.1016/j.jons.2016.08.006 .

[2] "Metaplastic Breast Cancer". Johns Hopkins Medicine. Johns Hopkins University. 2015-04-22. Archived from the original on 2015-02-15. Retrieved 2015-04-22.

[Luini-3] 1 2 3 4 5 Luini, Alberto; Aguilar, Marisel; Gatti, Giovanna; Fasani, Roberta; Botteri, Edoardo; Brito, Jack Antonio Diaz; Maisonneuve, Patrick; Vento, Anna Rita; Viale, Giuseppe (2007-01-23). "Metaplastic carcinoma of the breast, an unusual disease with worse prognosis: the experience of the European Institute of Oncology and review of the literature". Breast Cancer Research and Treatment. 101 (3): 349–353. doi:10.1007/s10549-006-9301-1. ISSN 0167-6806.

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