Carcinoid Tumor of the Breast
A carcinoid tumor is a slow-growing type of neuroendocrine tumor that originates in the cells that function as part of the neuroendocrine system.
A carcinoid tumor that occurs as a primary breast lesion is extremely rare. Normally, a carcinoid tumor presenting in the breast will represent metastasis from another area of the body.
A carcinoid tumor is most likely to start in the ‘hormone-producing’ cells. This is why they are more likely to occur in the:-
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What Causes Carcinoid Tumor of the Breast?
The exact cause of a carcinoid tumor, including carcinoid breast tumors, is unknown. In fact, carcinoid tumors, generally speaking, are far more common in men than in women.
Histologically, carcinoid breast carcinoma can mimic the appearance of breast adenocarcinoma. Radiologically and clinically, carcinoid breast tumors can easily be mistaken for conventional breast cancers. This is true even when the patient has a known history of a carcinoid tumor somewhere else in the body.
So, probably the most important aspect of the carcinoid tumor is to determine whether it is a primary or secondary tumor.
Carcinoid breast tumors are associated with the endocrine system
The endocrine system basically refers to the various cells in the body that produce hormones. Hormones, of course, are various chemical substances that enter the bloodstream and then exert a specific regulatory effect on the activity of other organs or cells. Because endocrine tumors arise from hormone-producing cells, the tumor itself can produce hormones and cause serious illness.
A carcinoid tumor of the breast usually develops from enterochromaffin cells. These are hormone-producing cells and are most commonly found in the small intestine. They also occur in the:-
- bile ducts
- breast – only a small amount of these cells.
As a result, carcinoid tumors are most commonly found in the ‘midgut’ region, accounting for 75% to 87% of all cases. The next most common locations for the carcinoid tumor is the respiratory tract, which accounts for about 28% of cases.
A primary carcinoid breast tumor is extremely rare. In fact, there is still a certain amount of professional dispute in terms of whether primary carcinoid breast cancers are frequent enough to justify a classification.
Those who argue against point to the fact that, in most cases, a primary cancer site is eventually found somewhere else in the body. That primary site may simply have missed detection at the time of detection of the breast tumor.
Carcinoid breast tumors are far more likely to arise from metastasis
It is more likely that a carcinoid breast carcinoma would develop as a result of metastasis from another primary site, but even this is very rare.
However, overall, breast tumors that develop as a result of metastasis from other locations account for less than 2% of all breast tumors.
Common cancers that have been known to metastasize to the breast include:-
- hematopoietic system
- malignant melanoma
If a woman has a clinically detectable breast mass, and a history of carcinoid activity anywhere in the body, then suspicion of metastasis rather than primary breast cancer should be high. It is very important to determine this, as there are serious ramifications regarding treatment.
Carcinoid breast tumors are a subset of neuroendocrine tumors
At the present time, physicians consider carcinoid tumors to be distinctive from neuroendocrine breast tumors. Carcinoid tumors can really be thought of as a subset of neuroendocrine tumors.
Furthermore, the carcinoid tumor is far more likely to appear in the gastrointestinal tract (appendix, stomach, small intestine, colon, rectum) and in the lungs, rather than in the breast.
Out of interest, there is an important distinction in terminology between neuroendocrine tumors and neuroendocrine cancers.
A neuroendocrine breast tumor is one which looks benign but has the potential to spread to other parts of the body. Neuroendocrine cancer is an abnormal growth of altered neuroendocrine cells, which may spread to other parts of the body.
Carcinoid breast tumors may cause Carcinoid Syndrome
Because carcinoid tumors develop from enterochromaffin cells, they often will retain the capability to produce the same hormones, and can still do so in large quantities.
The hormones which are produced by carcinoid tumor cells can still circulate in the blood and cause quite a few adverse symptoms. This is termed ‘carcinoid syndrome‘. Basically, it is a combination of symptoms, depending upon which kinds of hormones are released.
Common hormones that carcinoid tumors release (including breast carcinoid tumors) are:-
Other symptoms that one might experience as the result of a carcinoid breast tumor include diarrhea or skin flushing. One thing to remember though is those carcinoid tumors, including carcinoid breast tumors, would not likely produce any symptoms until late in the disease.
Approximately 10% of patients with carcinoid breast tumors will experience the carcinoid syndrome.
Histological features of Carcinoid Tumor of the breast
Histologically, carcinoid breast carcinoma may mimic ductal adenocarcinoma of the breast. Carcinoid breast carcinoma cells will tend to have round to oval nuclei, with a fine, reticular chromatin pattern. Mitoses are generally rare, and necrosis is also quite often absent.
Treatment and prognosis for carcinoid breast carcinoma
Treatment will depend on whether or not the carcinoid breast carcinoma is primary or secondary and upon the stage of tumor growth. If the carcinoid tumor is a result of metastasis, then lumpectomy alone should provide an effective treatment.
Axillary dissection should be avoided, and mastectomy is also probably not necessary. It often requires a highly experienced cancer specialist to figure out the proper diagnosis, early in the proceedings. Typically either a lumpectomy or partial mastectomy is performed to remove the tumor.
The patient will likely receive adjuvant radiation therapy, but chemical therapy has proven to have little benefit for carcinoid tumors and will not likely be useful.
Quite frequently, medics will treat carcinoid tumor of the breast with biological therapy (also sometimes called immunotherapy). Essentially, this means using the body’s immune system to fight cancer. Immunotherapy has been shown to reduce the size of carcinoid tumors in as many as 17% of patients, and can also slow the growth of metastatic tumors.
Some commonly used biological agents for the treatment of carcinoid breast cancers include interferon and Sandostatin®. There are quite a few negative side-effects to biological treatments, however.
Five year survival almost 90%
On the whole, the prognosis for carcinoid breast cancer is fairly positive. Most carcinoid breast tumors are quite slow-growing. The five-year survival rate following the surgical removal of a carcinoid tumor (which has not metastasized) can be as high as 90%.
However, in about 45% of patients, metastasis is already present at the time of diagnosis, and in most cases, a breast carcinoid tumor is in fact a metastasis from another site.
Still, most women, even with a metastatic breast carcinoma will quite often live another 10 to 15 years. But if a carcinoid tumor has metastasized to the liver, then the prognosis is poor.
- Neuroendocrine Breast Cancer
- Neuroendocrine Markers
- Index of ALL our Articles on Types of Breast Cancer
- Index of ALL our Articles on Breast Cancer Survival and Incidence Rates
- Metastatic Breast Cancer: Survival Rates for Stage IV
- Rare Breast Cancers
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