Mammary secretory carcinoma

Mammary Secretory Carcinoma is a rare type of breast cancer that is characterized by its unique molecular and histological features. It was first identified in the salivary glands as Secretory Carcinoma of the Salivary Gland and later recognized in the breast. This type of cancer is known for its secretion of mucinous or eosinophilic material, which is a hallmark of the disease. It is important to distinguish Mammary Secretory Carcinoma from other types of breast cancer due to its distinct clinical behavior, treatment responses, and prognosis.

Epidemiology

Mammary Secretory Carcinoma is considered a rare entity among breast cancers. It accounts for a very small percentage of all breast cancer cases. The exact incidence is difficult to determine due to its rarity. It can occur in individuals of any age but has been reported to have a wide age distribution, with cases occurring in both pediatric and adult populations.

Pathogenesis

The pathogenesis of Mammary Secretory Carcinoma is closely linked to a specific genetic alteration; a translocation involving the ETV6 gene on chromosome 12 (12p13) and the NTRK3 gene on chromosome 15 (15q25). This translocation creates an ETV6-NTRK3 fusion gene, which is thought to play a crucial role in the development of this cancer by activating various signaling pathways that promote cell growth and survival.

Clinical Features

Patients with Mammary Secretory Carcinoma may present with a painless, firm mass in the breast. The tumor can vary in size and is not always palpable. In some cases, nipple discharge may be present. Due to its rarity and non-specific presentation, it can be easily confused with other benign and malignant conditions of the breast.

Diagnosis

The diagnosis of Mammary Secretory Carcinoma is primarily based on histopathological examination and molecular genetic testing. Histologically, the tumor is characterized by its secretory features, with abundant extracellular eosinophilic secretory material. Immunohistochemistry is used to confirm the diagnosis, with tumors typically expressing S100, mammaglobin, and vimentin. The definitive diagnosis is made by identifying the ETV6-NTRK3 fusion gene through molecular genetic testing.

Treatment

The treatment for Mammary Secretory Carcinoma typically involves surgical resection, which may be followed by radiation therapy or chemotherapy, depending on the stage of the disease and the presence of metastases. The role of targeted therapy, particularly inhibitors targeting the NTRK fusion protein, is an area of ongoing research. The treatment approach should be individualized based on the patient's overall health, the extent of the disease, and the molecular characteristics of the tumor.

Prognosis

The prognosis of Mammary Secretory Carcinoma is generally favorable, especially in cases detected early and treated appropriately. However, like all cancers, the outcome can vary depending on various factors, including tumor size, lymph node involvement, and the presence of distant metastases. Long-term follow-up is necessary to monitor for recurrence and manage any late effects of treatment.

Conclusion

Mammary Secretory Carcinoma is a distinct subtype of breast cancer with unique clinical, histological, and molecular features. Its recognition is crucial for the appropriate management and treatment of affected individuals. Ongoing research into the molecular underpinnings of this disease may provide new avenues for targeted therapies, improving outcomes for patients with this rare cancer.

NIH genetic and rare disease info

• NIH info on Mammary secretory carcinoma

Mammary secretory carcinoma is a rare disease.