Hidradenocarcinoma

The cause of hidradenocarcinoma is unknown.  The only known risk factor is the prior presence of a benign hidradenoma.  Molecular genetic changes in the cells of the hidradenocarcinoma have been found in some cases, but more studies must be performed before medical researchers can determine if a pattern exists.^{[1][2][3][4][5]} 

Please note, molecular genetic changes are also called somatic mutations or acquired mutations.  You are not born with an acquired mutation, instead the change happens some time during your life. This change in the gene occurs in one cell, and then is passed on to any new cells that are the offspring of that cell. This kind of mutation cannot be passed on to your children. Acquired mutations are much more common than inherited mutations. Most cancers are caused by acquired mutations.^[6] 

Medical researchers have not found any genetic change which a person is born with that may increase their risk for developing hidradenocarcinoma nor are there any reports in the literature which suggest this rare cancer runs in families.^[1][2][3]

Because hidradenocarcinoma is quite rare, there are no established guidelines for treatment.   The most accepted form of treatment is wide local excision of the tumor, but due to the high risk that the tumor will grow back and frequent metastasis to nearby lymph nodes and other parts of the body, some doctors also suggest radiation therapy and/or chemotherapy after surgery.^[1][2]  

Newer targeted therapies like trastuzumab, epidermal growth factor receptor (EGFR) inhibitors, PI3K/Akt/mTOR pathway inhibitors (targets a pathway believed to be involved in controlling cell growth and division), hormonal agents like antiandrogens, and electrochemotherapy (the use of electrical pulses to help get the chemo drugs into the cancer cells) may also be offered.  Most of these therapies have only been reported in isolated case reports and often with conflicting results. Therefore it is difficult to determine which therapy or combination of therapies are the best treatment option. Options are usually determined by the size and location of the cancer and the extent to which cancer cells may have spread to nearby tissues..  Many researchers are hoping if there is a better understanding of the molecular genetic changes which happen in the cells of hidradenocarcinoma, the use of targeted therapies will improve long term prognosis.^[1][2]  

Hidradenocarcinomas are known to be aggressive and have a high rate of growing again in the same area and metastasizing or spreading to other parts of the body, especially lymph nodes. With surgery alone, five year survival rate is less than 30%. The chance of the tumor returning after surgery is as high as 50%.  It is unclear if the addition of radiation therapy, chemotherapy or targeted therapies improves the long term outlook.^[1][2]

Factors which seem to predict a better outcome include finding the cancer at an early stage and the ability to completely surgically remove the tumor. Prognosis is also better for younger individuals and those in good health.  Tumors which do not respond to treatment have a poorer outlook, while the outlook for recurrent tumors is difficult to predict.^[1][2]

Hidradenocarcinoma is very rare. Cancerous tumors which begin in the major sweat glands (eccrine carcinomas) make up less that 0.01% of all skin cancers. Hidradenocarcinoma accounts for approximately 6% of cancerous eccrine tumors and less than 0.001% of all tumors.^{[2] [7]}