Basal cell carcinoma, one of the most common varieties of skin cancer arises from the basal cells of the skin. These basal cells are known to produce new cells which replace older cells. Although it is considered to be malignant, unlike other malignant lesions basal cell carcinoma rarely spread to distant organs.

This condition affects about 30% of the Caucasians and in the United States alone every year over 800,000 cases of basal cell carcinoma is reported. This condition is usually more common in fair skinned people with family history basal cell carcinoma. Other than positive family history prolonged sun exposure (UV ray exposure) is another risk factor associated with basal cell carcinoma.

Skin lesions of basal cell carcinoma usually appear in the head and neck region however now-a-days lesions are also commonly seen in the trunk and non or rarely sun exposed parts of the body.
Skin lesions of basal cell carcinoma may present in different forms however waxy bumps are the most common presentation.
Treatment options of basal cell carcinoma include surgical excision of the lesion, freezing, Mohs surgery, drugs etc.

Causes
Basal cell carcinoma arises from the basal cells of the skin. Basal cells are located in the basal cell layer in the outermost layer of the skin, the epidermis. New cells are produced in this layer of skin which pushes the other older cells from beneath towards the cell surface. The older cells die and are removed by sloughing off of these cells.

The older cells of the body are replaced by newer cells. The biological process through which older cells die and are removed from the body is known as apoptosis (programmed cell death) and the process of new ell production si known as cell division. Both the process of apoptosis and cell division are highly regulated by various factors and an optimum balance between the two is maintained. In any type of cancer there is disruption of the balance like stimulation of cell division and suppression of cell death (apoptosis) abnormal immortal cells appear with the capacity to spread to other organs (metastasize).

Now it is not clearly known which are factors which trigger loss of the balance; however genetic factor is known to play an important role. Sometimes unexpected permanent change (mutation) in the genetic material may occur resulting to suppression or stimulation of the regulatory factors leading to abnormal cancerous cells production.

Again the factors which may trigger mutation is not known but one of the potentially responsible factors is chronic exposure to UV radiation present in the sunlight. UV radiation as present in the commercial tanning lamps and in tanning beds may also be responsible. However basal cell carcinoma may also occur in parts of the body with least sun exposure indicating that there are other factors which increases the susceptibility of a person to basal cell carcinoma. Exposure to toxic environmental substances, infections which have the capacity to impair the immune system of the affected body are included in the list of other potential substances triggering mutation.

Risk factors
Common risk factors include
1. Chronic exposure to sun light for prolonged period especially if exposure occurs before 18 years of age. This fact is further established by the fact that the cases of basal cell carcinoma occur in people living in the equatorial countries as well as in the high altitude areas. Presence of blistering sun burn is also another important associated factor with the lesions of basal cell carcinoma.
2. Radiation exposure: exposure to radiation may occur as a part of treatment of other varieties of cancer or during treatment of psoriasis. Psoralen and UV A exposure are one of the treatment options treatment.
3. Fair skinned people are more at risk of developing basal cell carcinoma. Having light skin increases the chance of having freckles and getting sun burned and thus increased susceptibility to basal cell carcinoma. Black people are less commonly affected.
4. Men are likely at risk of suffering from basal cell carcinoma
5. In majority of the cases basal cell carcinoma occur in people above 50 years of age
6. Family history of basal cell carcinoma
7. Intake of drugs which suppress the normal function of the immune system especially in people about to or already undergone organ transplant surgery, stem cell or bone marrow transplant may increase the risk of suffering from skin cancer including basal cell carcinoma.
8. Exposure to arsenic may also increases the risk basal cell carcinoma. Arsenic exposure is more common in farmers, factory workers, people living near smelting pelts etc.
9. Suffering from certain varieties of inherited genetic disorder may increase the risk of suffering from basal cell carcinoma. Xeroderma pigmentosum is one such inherited disease where the affected persons have highly sensitive skin especially towards exposure to sunlight and there is also impaired ability of the skin to recover from UV ray related skin injuries.

Treatment
There are various treatment options available depending upon the nature, location and extent of the disease.
Common options include
1. Electrodissection and curettage: this procedure includes scraping of the cancerous cells and then searing of the base suing an electric needle.
2. Surgical excision of the lesion with adjacent healthy margin of tissue
3. Freezing: in this procedure cancerous cells are killed by liquid nitrogen
4. Mohs surgery: in this procedure abnormal cells are removed layer by layer until normal later of skin becomes visible.
5. Local application of drugs like imiquimod, flurouracil on lesions located on the superficial layers of the skin
6. For advanced cases of basal cell carcinoma the drug vismodegib is prescribed.