Skin Cancer

Non-melanoma skin cancers are the most common human cancers, with an annual incidence surpassing that of lung, breast, prostate, and colon cancers combined. In the US, one in five individuals will develop non-melanoma skin cancer in their lifetime. This prevalence continues to rise due to increased life expectancy and a growing elderly population, heightened environmental solar radiation, and the popularity of leisure activities involving UV exposure (both natural sunbathing and artificial tanning beds).

Prognosis depends on the tumor type, its location on the body, and host characteristics. Prevention and early detection are crucial given the curability in most cases.

Basal Cell Carcinoma (BCC)

This type of cancer is the most common in humans. The primary carcinogenic factor associated with it is ultraviolet (UV) radiation, whether from natural or artificial sources. Intermittent recreational sun exposure or intense exposure (such as sunburn), especially during childhood and adolescence, significantly increases BCC risk. Indoor tanning with tanning beds is also strongly linked to an increased risk of this cancer. Patients with fair skin who are prone to sunburn are more susceptible than those with darker skin.

Other predisposing factors include ionizing radiation, chemicals (arsenic, aromatic hydrocarbons, etc.), PUVA therapy, certain genetic and hereditary syndromes, and immunosuppression.

Symptoms usually include a single, slow-growing lesion on sun-exposed skin. However, multiple lesions are not uncommon. It typically has no other symptoms but may ulcerate and bleed, especially as it grows. Over 50% of cases appear on the face and ears, and about 30% on the nose. However, it can appear anywhere on the body.

Diagnosis is made by biopsy by a physician and sent to a pathologist for histological examination. Definitive treatment is surgical. If surgery is not possible or too risky for a specific patient, radiotherapy can also be performed. If left untreated, the lesion spreads, causing disfigurement and destruction of the skin and surrounding tissues, but distant metastasis to various body parts and organs is rare, unlike other cancers.

Squamous Cell Carcinoma (SCC)

This type of skin cancer, like basal cell carcinoma, usually occurs in older individuals with a history of chronic UV exposure. This type has the potential for rapid growth and carries a low but significant risk of distant metastasis and mortality. It is also one of the most common human cancers, but its exact prevalence is unknown due to incomplete reporting of all cases. The incidence of this disease in individuals over 70 is 10 times higher than in 30-44 year olds. Incidence is higher in men. Also, in areas with higher UV exposure, it is 5 to 10 times higher (both UVA and UVB play a role), and individuals with fair skin, hair, and eyes have a higher susceptibility. Chronic immunosuppression, whether due to diseases causing it or immunosuppressive drugs, increases susceptibility. Other factors include certain chemicals (petroleum, tar, arsenic…), exposure to ionizing radiation (such as X-rays and gamma rays), PUVA therapy, HPV virus, and smoking. This cancer can also develop on chronic wounds such as severe burns and scars, discoid lupus erythematosus, and osteomyelitis. Certain congenital syndromes and genetic disorders also increase susceptibility to this disease.

Visually, it starts as pre-cancerous skin patches and grows into raised lesions, creating a prominent and sometimes ulcerated surface. If left untreated, lymph nodes may become involved, and in rare but significant cases, after spreading due to neglect and lack of treatment, it can lead to metastasis to other organs, in which case the prognosis is very poor and often fatal. Diagnosis is made by histological biopsy, and treatment consists of surgery, radiotherapy, or a combination of both, which can completely eradicate the disease in non-advanced cases. In advanced cases, injectable drugs or chemotherapy may also be used.
In addition to the two types mentioned, there are many other types of skin cancers that are less common and beyond the scope of this discussion. Also, melanoma, which accounts for less than 5% of skin cancers but over 70% of their mortality, requires another opportunity for discussion.