Adenoid cystic carcinoma – causes, symptoms & therapy

Adenoid cystic carcinoma is a malignant tumor of glandular tissue. It arises from the myoepithelial cells of the glands. The myoepithelial cells are responsible for the initiation of secretion and secretion transport. The salivary glands in the head and neck area are particularly affected by adenoid cystic carcinoma. This tumor most commonly manifests itself in the parotid, mandibular or small salivary glands.

However, manifestations in the nose, paranasal sinuses, lacrimal glands, trachea, larynx, bronchi, mammary glands, lungs or skin have also been observed. The cervix, prostate, ear canal, or Bartholin’s gland can also be affected. This cancer is slightly more common in women than in men. The growth of adenoid cystic carcinoma is initially very slow, so that the five-year survival rate of about 89 percent is very favorable.

However, due to the spread of growth and the possible formation of metastases , the prognosis for further five-year survival rates is deteriorating noticeably. The term “adenoid cystic carcinoma” was first used by pathologist James Ewing because of the typical appearance of this tumor. Because it grows with the formation of cystic or pseudocystic cavities. Tubular, sieve-like, and solid growth patterns are found. The tumor infiltrates the neighboring tissue and orientates itself on the existing nerve structures during growth. Tubular and sieve-like tumors have a better prognosis than solid growing ones.

causes

  Little is known about the causes of adenoid cystic carcinoma. To date, no environmental or genetic risk factors have been identified. There are also no underlying medical conditions known to be of particular risk. However, in the advanced forms of the tumor, it has been shown that the tumor suppressor gene p53 is often inactive. It has not yet been possible to find out whether this inactivation occurs as part of the cancer or whether it is the cause of at least one form of adenoid cystic carcinoma. More recent investigations often point to deviations in the chromosomal region 1p32-p36. Deletions occur in these sections.

symptoms and course

Typical symptoms of adenoid cystic carcinoma:

• signs of paralysis in the face

• discomfort

• Swollen lymph nodes

Adenoid cystic carcinoma presents as a well-circumscribed, solid tumor on the associated gland. The tumors can vary in size and are light brown in color. Growth can have different patterns. There are tubular (tube-shaped), cribriform (sieve-shaped) and solid growth patterns. The tumor grows infiltratively into the tissue. Further growth occurs along nerve cords. This is followed by the typical symptoms, which manifest themselves in signs of paralysis in the face and diffuse pain and discomfort.

The affected salivary gland slowly swells. If the lymph glands are affected, the lymph glands also become swollen. In the beginning, adenoid cystic carcinoma is characterized by very slow growth. As a result, the cancer is often diagnosed at a very late stage. An infestation of the lymph glands is given as 5 to 25 percent. Distant metastases occur in approximately 25 to 55 percent of cases. Distant metastases can be lung, bone , brain or liverto be affected. Despite the slow growth, curative therapy is often no longer possible at the beginning of the disease. The reason for this is the infiltrative growth along neuronal structures, which makes complete removal of the cancer very difficult. Therefore, the course of the disease is often characterized by the occurrence of recurrences.

Diagnose

After the first symptoms appear, such as chronic swelling of the salivary glands or facial paralysis, a definitive diagnosis can only be made by taking tissue samples and examining them. Benign adenomas or other malignant tumors must be excluded in the differential diagnosis. When adenoid cystic carcinoma is diagnosed, imaging tests such as CT , MRI , or positron emission tomography can detect the spread of the cancer in the tissues. This is particularly important for successful treatment. Nevertheless, due to the complicated growth structure, it is often not possible to see the full extent of the tumor.

treatment and therapy

Ideally, an adenoid cystic carcinoma can be completely healed if all the affected tissue is removed during the resection of the tumor. This requires maintaining a sufficient safety distance from the diseased tissue. More tissue is removed and another tissue examination is carried out at the edges of the incision. Despite these measures, due to the complicated structure of the tumor, its complete resection is not always possible.

Despite the slow growth, the long-term prognosis for this disease is not good in many cases. If only a few diseased cells remain after the surgical removal of the tumor, a recurrence will always occur. However, since growth is very slow, relapse often takes many years. Chemotherapy alone is not successful due to slow growth. Only radiotherapy can reduce the recurrence rate somewhat. But even with the radiation, it is often not possible to reach all affected regions. Studies are currently being carried out to determine whether the combination of chemotherapy and radiotherapy can achieve higher healing success rates.

If the lymph nodes are affected, a so-called neck dissection can prevent the further spread of the cancer cells. In a neck dissection, the lymph nodes in the neck are surgically removed. Due to the slow growth of adenoid cystic carcinoma, the survival rate in the first five years of the disease is up to 89 percent. If the cancer cannot be completely removed, the five-year survival rate drops to 60 percent after another five years and to 40 percent thereafter. In patients with distant metastases, the five-year survival rate is around 20 percent.

prevention

Since the causes of adenoid cystic carcinoma are still unknown, no recommendations for its prevention can be given. However, once the disease is diagnosed, treatment should begin immediately.