What is Secretory Carcinoma?
Secretory carcinoma is a rare type of cancer that most commonly develops in the breast or salivary glands, but it can occasionally occur in other parts of the body. It is defined by a specific genetic change called the ETV6–NTRK3 gene fusion. This fusion happens when two separate genes join together abnormally, causing cells to grow uncontrollably and form a tumour.
This cancer was previously called “mammary analogue secretory carcinoma” when found in salivary glands because it closely resembles a rare breast cancer under the microscope. Today, doctors classify it based on its genetic feature rather than just its location.
It is considered a low- to intermediate-grade cancer, meaning it usually grows slowly, but in some cases it can behave more aggressively.
Incidence
Secretory carcinoma is rare. In the breast, it can occur in both adults and children, though it is uncommon overall. In the salivary glands, it most often affects middle-aged adults and typically arises in the parotid gland, which is located near the ear.
Both males and females can be affected, although breast cases are more common in females.
Symptoms
Symptoms depend on where the tumour develops. In the breast, it usually appears as a painless, slow-growing lump. In the salivary gland, it may present as a swelling near the jaw or in front of the ear. The lump often grows gradually and may not cause pain in early stages.
If the tumour becomes large, it can cause pressure symptoms, such as discomfort, difficulty swallowing, or facial weakness in rare cases involving the salivary glands. In most patients, symptoms develop slowly.
Diagnosis
Diagnosis begins with imaging tests such as ultrasound, mammography, MRI, or CT scan depending on the tumour location. A biopsy is necessary to confirm the diagnosis.
Under the microscope, the tumour cells produce secretions, which is why it is called “secretory” carcinoma. However, the most important step is molecular testing to detect the ETV6–NTRK3 gene fusion, which confirms the diagnosis.
This genetic finding is important because it also helps guide treatment decisions.
Treatment
The main treatment is surgical removal of the tumour. If the tumour is completely removed and has not spread, surgery alone may be sufficient.
In cases where the cancer has spread or cannot be fully removed, additional treatments such as radiation therapy may be used. Importantly, because this tumour contains an NTRK gene fusion, patients may benefit from targeted therapy with NTRK inhibitors, which are newer medications specifically designed to block the abnormal protein caused by this gene fusion.
These targeted therapies have shown very promising results in advanced cases.
Prognosis
The prognosis for secretory carcinoma is generally good, especially when detected early and completely removed. Many patients achieve long-term survival.
However, in rare cases where the tumour spreads to lymph nodes or distant organs, the disease may behave more aggressively. The availability of targeted NTRK therapy has significantly improved outcomes in advanced or metastatic cases.
Regular follow-up is important to monitor for recurrence.
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