Skin cancer is a malignant tumor that forms in the skin cells. Although the cancer can begin on any part of the skin, most skin cancer develops on parts of the skin exposed to the sun. Depending on the group of cells affected, a skin cancer can be called basal cell carcinoma, squamous cell carcinoma or melanoma.
The skin is the largest organ of the body. It is composed of three main tissue layers: the epidermis, representing the superficial layer of the skin; the dermis, the deep layer beneath the epidermis; and the hypodermis the deepest layer of the skin which lies below the dermis. Your skin contains small specialized structures such as nerves, hair, nails and various types of glands.
The skin is one of the most important organs of the body. It plays several roles essential to the functioning of the organism such as:
- synthesis of vitamin D
- storage and synthesis
- heat regulation
- and more…
Skin Cancer Statistics
According to the World Health Organization (WHO), it is estimated that over 2 million non-melanoma cancers (basal cell carcinoma and squamous cell carcinoma) and 200 000 malignant melanoma cases occur each year worldwide. About 66 000 people die year of these skin cancers.
In the United States alone, basal cell carcinoma, squamous cell carcinoma and melanoma cause about 8500 deaths yearly (basal cell carcinoma and squamous cell carcinoma deaths 2000, melanoma 6500 deaths). The National Cancer Institute (NCI) has estimated that 74,610 men and women (42,920 men and 31,690 women) were diagnosed with and 11,590 men and women died of cancer of the skin (excl. basal and squamous) in 2009.
The incidence of skin cancer varies with age. From 2002-2006, the median age at diagnosis for cancer of the skin (excl. basal and squamous) was 60 years of age. Ages and percentages of people diagnosed were approximately:
- 9% under age 20;
- 7% between 20 and 34;
- 0% between 35 and 44;
- 3% between 45 and 54;
- 4% between 55 and 64;
- 8% between 65 and 74;
- 6% between 75 and 84;
- 3% 85+ years of age.
Skin Cancer Causes
Skin cancer occurs when DNA from some healthy cells of the skin undergo a mutation that causes them to multiply anarchically. In certain type of skin cancer, mainly basal cell carcinoma, the mutation is caused by damage to a gene called PTC by ultraviolet (UV) radiation from sunlight and/or commercial tanning lamps and tanning beds.
Unlike many types of cancer, the causes of skin cancer are more or less known. Numerous studies have demonstrated that basal cell carcinoma, squamous cell carcinoma and melanoma are associated with significant exposure to sunlight. The risk is even higher when the exposure starts in the early years of life. That is, prolonged and continuous exposure to sunlight in childhood is the main factor that can cause skin cancer later in life.
Although exposure to ultraviolet rays from the sun is the main cause of skin cancer, artificial sources of ultraviolet radiation (tanning lamps and tanning beds) are also suspected in the development of the disease. It is shown prolonged skin contact with certain chemicals can increase the risk of skin cancer.
This risk is higher if you have fair skin, blond or red hair, blue or green eyes, freckles and moles. In addition, if you tan easily, you’re more likely to develop cancer of the skin because your skin is less pigmented and less protected from the sun.
Skin Cancer Risk Factors
Skin cancer is a multifactorial disease; several factors may contribute to its development. The most common factors that are linked to the onset of skin cancer include:
- Age– risk of skin cancer increases with age
- exposure to ultraviolet light
- family history of skin cancer
- personal history of skin cancer
- excessive sun exposure
- previous radiotherapy
- exposure to chemicals that irritate or attack your skin cells
- history of sunburn
- having many benign moles (dysplastic nevi)
- chronic precancerous skin lesions such as rough and scaly patches
- weakened immune system
- certain professions such as welder and boilermakers
- outdoor workers: farmers, construction workers, etc..
- prolonged exposure to environmental chemicals such as herbicides
- some genetic diseases of the skin: albinism, xeroderma pigmentosa, etc..
- Living at high altitudes or near the South Pole – the highest incidence of melanoma is found in Australia and New Zealand.
Skin Cancer Symptoms
Early signs and symptoms of skin cancer often go unnoticed. Initially, most skin cancers do not cause any pain, itching or bleeding. People tend to confuse the disease with other common skin problems.
Skin cancer develops mostly on the sun-exposed areas of the skin: scalp, face, lips, ears, neck, chest, arms and hands. In some cases, the cancer can develop on the legs (mostly in women), palms, beneath the fingernails, spaces between toes, under toenails, and genital area.
Characteristic and location of symptoms of skin cancer depend on the type of cancer you have. However, in most cases, the first sign of a basal cell carcinoma is a whitish bump which eventually bleeds and makes a crust that keeps coming. A squamous cell carcinoma can be characterized by a red, dry and scaly nodule or lesion. The lesion tends to be small at the beginning and grow as the tumor progresses.
Basal cell carcinoma – basal cell carcinoma tends to appear on the scalp and upper trunk, or face more precisely on the nose, eyelids, lips, cheeks, forehead or temples. The lesion may also develop on the chest or back. In general, basal cell carcinoma having the following characteristics:
- red or pink bump on the face, ears or neck;
- little flesh-colored or brown scar-like lesion chest or back
- A lesion that do not heal.
Squamous cell carcinoma – this form of skin cancer develops most often in areas exposed to the sun: head and neck, upper body, forearms, hands and nails; however, the lesion can appear on other areas such as the mouth or genitals. In general, squamous cell carcinoma is characterized by either one of the following signs:
- a dry and red nodule that tends to be firm and scaly;
- A firm, warty, pink or whitish lesion that does not heal.
Melanoma – melanoma can develop anywhere on your body as an irregular large brownish or dark growth on your skin. Melanoma may also begin in or near an existing nevus (sharply-circumscribed and chronic lesion of the skin). The lesion tends to progress rapidly, which makes it the most serious form of skin cancer. Melanoma is responsible for nearly 75% of deaths from skin cancer. In most cases, melanoma is characterized by:
- a mole that changes color or size, and has an irregular contour;
- a blackish lesion on the skin or mucous membrane of:
o genital organs
Skin Cancer Complications
Some of complications that can be resulted from skin cancer are:
Basal cell and squamous cell carcinomas – if left untreated or poorly treated basal cell and squamous cell carcinomas can spread locally and cause destructive effects in your organism. Metastasis of basal cell or squamous cell carcinomas is very rare. A very advanced cancer of the lining of the mouth or genitals, however, can form metastases and lead to death.
Melanoma – an advanced melanoma may cause complications even after treatment. Thus, after
treatment, a prolonged monitoring is necessary to detect recurrence and ensure there are no other suspicious lesions. In the absence of effective treatment and increased surveillance, a melanoma can spread and give rise to metastases in these sites:
- lymph nodes
- spinal cord
Having metastatic skin cancer, your survival chances decrease dramatically. Follow your doctor’s appointments and take all precautionary measures to prevent recurrence of cancer after treatment.
Skin Cancer Diagnosis
Skin cancer diagnosis can be done by physical examination. During the exam, your dermatologist will examine your skin looking for lesions that indicate presence of cancer. Your dermatologist may suspect and differentiate a cancerous lesion from other skin problems. In some cases, he can complete the exam by a dermatoscopic analysis, use of magnifying glass to increase the size of the tumor on your skin.
However, to rule out other skin diseases that have similar symptoms to skin cancer, a biopsy is necessary. Your physician will take samples from the malignancy for laboratory analysis (biopsy). This histological examination is essential to accurately confirm the diagnosis. Besides the confirmation of the cancer, the biopsy can also help your doctor to determine the severity of the tumor.
Skin Cancer Stages
Melanoma – once the cancer is found in your skin, it is necessary to find its stage. In general, the stage of melanoma is measured from the size of the tumor and the presence of cancerous cells in any lymph nodes or other parts of the body: lungs, brain, spinal cord, liver or bone. Your oncologist can use the result of the biopsy to determine the stage of the cancer.
- Melanomain Situ– also called stage 0, this is the genesis of the cancer cells; your five-year survival chance is about 99.9%.
- Stage I –at this stage, the melanoma is invasive; although it is well localized, the cancer can spread into other areas of your body. Your survival chance is less than 95%.
- Stage II –stage 2 is considered as a high risk melanoma; the cancer can spread to other areas of the body, and survival chance is about 40-85%.
- Stage III –at stage 3, the cancer is more aggressive; the risk of regional metastasis is higher; survival chance is estimated at 25-60%.
- Stage IV –your survival chance has decreased considerably to 9-15%; the cancer is often associated with distant metastases.
- Stage IV– at stage 4, the tumor has become more aggressive; the cancer has spread beyond your skin to other organs, such as your lungs, liver and bone. survival chance has decreased considerably.
Squamous cell carcinoma – In general, squamous cell carcinoma develops in three stages:
- Stage I– at stage 1, the cancer remains superficially in the tissue where it originates; chances of surviving is very high.
- Stage II– a stage 2, the squamous cell carcinoma has infiltrated deeply into the tissue of the skin, and it is associated with a high risk of recurrence in cases of limited surgery. Loco-regional invasion may also occur, particularly in the pelvis. In addition, the cancer may have affected the bone tissue surrounding the tumor.
- Stage III– at this stage, the cancer has become more aggressive with high risk of lymph node metastases; survival chance decreases significantly. Without a prompt and effective treatment, the cancer can travel though the bloodstream to form other tumor in surrounding or distant areas from the tumor: lungs, liver, brain or bone.
Skin Cancer Treatment
The treatment of skin cancer depends on many factors: stage and location of the tumor, age and your health. Survival chance is higher when the cancer is diagnosed early. In general, the treatment of skin cancer includes surgery, electrocautery, cryosurgery, radiotherapy, chemotherapy and immunotherapy; dynamic photherapy can also be used.
Also called cryosurgery, cryoablation or targeted cryoablation therapy, cryotherapy is the application of extreme cold to destroy diseased tissue, including cancerous cells. During the procedure, your physician uses a cryoprobe, a surgical instrument used to conduct intense cold to small areas of body tissues in order to destroy them. The physician is guided by imaging techniques to position the cryoprobe precisely on the treated area. While he is freezing the tissue, he visualizes the movement of the device in real time on a monitor like a television screen.
Skin Cancer Surgery
Surgery is the essential treatment of skin cancer; In fact, most skin cancers diagnosed and removed early need no other therapeutic intervention after the surgery. It is estimated that 80% of skin cancers, detected early, are successfully treated with surgery. Depending on the extension of the tumor, your surgeon can perform an excisional surgery, laser therapy, Mohs surgery or curettage.
- Excisional surgery –this is, by far, the most common surgical treatment used to treat skin cancer. It consists of using a scalpel to remove cancerous tissue and a surrounding margin of healthy skin.
- Laser therapy –this method consists of using high-intensity light to kill cancerous tissue or to shrink or destroy tumors.
- Mohs surgery –this surgical procedure is used to treat large basal cell carcinoma and squamous cell carcinoma. During the procedure, your surgeon removes the skin growth layer by layer, and immediately examines each layer under microscopeto search for cancer cells.
- Curettage and electrodesiccation– this is a simple procedurepracticed, most of the times,in the cases ofsmall basal cell and squamous cell tumors. It consists of removing the tumor from the skin with a curette, a surgical instrument designed for scraping biological tissue or debris during a biopsy.After the tumor is removed, your surgeon will use an electric needle to cauterize the remaining cancer cells.
Skin cancer Chemotherapy
Chemotherapy is an important weapon in the treatment of advanced or metastatic skin cancer. It consists of using strong drugs to destroy cancer cells by preventing them from multiplying. The protocol varies depending on the stage of the cancer and your health. In early stage cancers, creams or lotions containing anti-cancer agents can be used to kill the cancer cells. These chemotherapeutic agents can be administered alone or in combination. Your doctor will use the option best suits your case.
Radiation Therapy (Radiotherapy)
Radiotherapy is a local treatment that affects the tumor and the area close to it. In general, it consists of using of ionizing radiation to destroy cancer cells. Radiation is often practiced in advanced or metastatic skin cancer to relieve symptoms. Radiotherapy can be used in association with surgical therapy or alone when surgery is not an option.
Biological Therapy (Immunotherapy)
Also called biological therapy, immunotherapy is the use of drugs to strengthen your immune system to help your body fight the cancer cells. These drugs act by activating your immune cells so they attack cancer cells and destroy them. Interferon and interleukin-2 are the two most used drugs in the treatment of melanoma. Some of their adverse effects include:
- Muscle aches.
Photodynamic Therapy (PDT)
This new form of therapy involves application of a photosensitizing substance (causing tissue susceptibility to certain lights) on the skin for several hours before exposing it to a particular light, which can be a blue or red. The substance is applied on the skin as a liquid or a cream containing aminolevulinic acid (5-ALA-HCl) or methyl aminolevulinate (MAL). Once on the skin, the drug is absorbed by the diseased tissue and sebaceous glands. Exposure to the light activates the substance in the tissue, and causes its destruction. You will need to avoid direct sunlight for at least six weeks after treatment.
Skin Cancer Survival Rates
After the treatment, the cancer can relapse. A second tumor may develop in other parts of your skin and even in distant tissues. Your chances of surviving depend largely on the stage and size of the tumor when it was diagnosed. However, the prognosis of skin cancer is not alarming, unlike many other forms of cancer. Basal cell or squamous cell carcinomas diagnosed and treated early are cured permanently in more than 90% of cases.
However, the survival rates tend to differ from one race to another. The overall 5-year relative survival rate for 1999-2005 from 17 SEER geographic areas was 91.1%. Five-year relative survival rates by race and sex were:
- 6% for white men;
- 7% for white women;
- 2% for black men;
- 1% for black women.
Skin Cancer Prevention
Unlike many type of cancer, skin cancer can be prevented. In fact, nearly 90% of skin cancers could be prevented by simply protecting the skin from ultraviolet rays. The following steps can help you prevent all types of skin cancer:
- Avoid tanning beds –tanning beds degage UVA rays that can penetrate into your skin and causes precancerous skin lesions, which can turn into cancer. Avoid them as long as you can.
- Regular medical visit– If you have been treated with melanoma, it is recommended that you see your doctor every six months for two years and then annually. These preventive measures are needed to detect a recurrence of the disease.
- Check your skin regularly– it is important to regularly check your skin to detect skin changes or changes in your moles. This is even more important if you have been diagnosed with melanoma.
- Avoid sun exposure– prolonged exposure to sunlight is the main risk factor for melanoma and therefore avoid them should be your first step in preventing skin cancer. In general, it is good to:
- avoid sunbathing
- wear protective clothing and a hat when you walk under the sun
- avoid sun exposure between 10 am and 4 pm
- Apply a protective sunscreen (20 index, at least) – renew it every two hours and after swimming.