Skin is a multi-layered organ, which is the first line of defence in a human body that is exposed to the various physical and chemical environments.

However, several types of skin cancer can affect an individual due to a number of reasons that might not be limited to only sunlight exposure. Therefore, we present this article on skin cancer, discussing everything one should know about the types, causes, treatment and symptoms of skin cancer.

Without any delay, let's know more!

Skin cancer is by far the commonest form of cancer that can be treated if detected early. Generally, skin cancers are locally destructive cancerous growth of epidermal cells. However, depending on their types and stages, certain skin cancers can metastasise, i.e., they can spread to other parts of the body and become life-threatening.

Furthermore, depending on skin cancer types, its symptoms vary. An early prognosis of the ailment will leave scope for its treatment. Therefore, let's learn about the types of skin cancer in the following section.

Broadly speaking, there are two categories of skin cancer:

1. Keratinocyte Carcinoma

Including basal and squamous cells, these are the common forms of skin cancer which is treatable if diagnosed early. These develop on the body parts which receive maximum sunlight, like the head and neck. On the other hand, squamous cell carcinoma is most common in immunosuppressed individuals and possesses the chance of a distant spread.

2. Melanoma

As a simple answer to the question "what is melanoma" it can be said that this type of cancer can become life-threatening, as it metastasises more than the basal and squamous cell carcinoma. Melanoma originates from melanocytes or the cells that produce colour for the skin. Sometimes benign moles developing from melanocytes on the back and chest of a man and a woman's legs can become cancerous.

Apart from this, there are other types of skin cancer like:

• Merkel cell skin cancer.
• Cutaneous lymphomas.
• Kaposi sarcoma.

However, skin cancer symptoms vary depending on its types. Therefore, it is vital to know everything about skin cancer signs.

Here are the symptoms of Basal Cell Carcinoma:

• Presence of pearly, shiny pink or red bump.
• The pink outgrowth or lesions are crusted at the centre with raised borders.
• The reddish patch of skin might get itchy, but it's not painful.
• There might be a white or yellow waxy area of skin that has a poorly defined border and looks like a scar. 

Symptoms of Squamous Cell Carcinoma:

• Bleeding scaly red patches of skin that have irregular borders.
• Any open sore that stays on for weeks.
• A raised outgrowth with a rough surface that is slightly indented in the middle.
• Presence of a wart-like growth.

Signs of Melanoma:

• Presence of large brownish spots with darker speckles.
• Any mole that changes colour, size, feel and bleeds.
• Small lesions with irregular borders that appear pink, white, blue-black or blue.
• Painful lesions that itch or burn.
• Dark lesions on palms, fingertips, toes, soles or mucous membranes like lining nose, mouth, vagina, or anus.

Apart from this, the signs of rare skin cancers include:

• People with weak immune systems like those with AIDS, following a line of medication that suppresses natural immunity, and those who underwent surgery like an organ transplant, etc., can have Kaposi sarcoma, a rare skin cancer forming in the skin's blood vessels.
• Firm, shiny nodules appearing on or beneath the skin and in hair follicles causes Merkel cell carcinoma. These nodules are present on the head, neck, and trunk.
• Sebaceous gland carcinoma occurs in the oil glands that appear hard and painless. They most often occur on the eyelid.
• Actinic keratoses are crusty lesions caused by damages from UV light in the facial area, scalp and back of the hands. They are also known as precancers because if left untreated, these conditions can turn into squamous cell carcinoma.

After knowing about the symptoms of skin cancer, it is vital to learn about its causes.

• Most skin cancer cases occur due to DNA mutations induced by the sun's harmful ultraviolet rays that affect the outermost layer of the skin that is the epidermis. During the initial stages, it is possible to control cancer growth due to natural immunity. However, with time, it may grow into masses of malignant cells that develop into tumours. 
• The most common form of skin cancer, basal cell carcinoma, is caused due to exposure to sunlight for a prolonged time. Basal cells produce new cells and lie beneath the squamous cells. Harmful UV rays from the sun can damage the DNA of these cells and cause the uncontrollable growth of cells. 
• Long-term exposure to cancer-causing chemicals can result in squamous cell carcinoma. Squamous cells lie below the outer surface of the skin and act as an inner lining. This type of cancer can occur within a burn or a scar and can sometimes be caused by certain types of human papillomavirus (HPV).

However, there are certain types of cancers like melanoma, whose causes are not yet clear. Most of the skin moles do not turn into melanoma. Further, exposure to UV rays can also be one of the causes of melanoma. But at times, melanomas develop in certain body parts which are not exposed to sunlight.

Therefore, after knowing the causes of this disease and its types, it is important to focus on the stages of cancer.

Detecting the stage of particular skin cancer helps in its treatment and helps understand the severity of the disease. For instance, early-stage skin cancer is treatable and does not pose much threat. A doctor determines the stage of skin cancer considering the following factors:

• Size of the tumour.
• Whether it has spread to lymph nodes.
• Spread to other parts of the body. 

Considering these, there are two categories of skin cancers for staging: nonmelanoma and melanoma. 

The nonmelanoma skin cancer stages include:

• 0: The cancerous cells have not spread beyond the epidermis, which is the skin's outermost protective layer.
• I: Cancerous cells may have spread to the dermis, but not longer than 2 centimetres.
• II: The cancer is more than 2 centimetres in length but has not spread to the nearby lymph nodes.
• III: It has spread from the primary tumour to the nearby tissues or bones and is larger than 3 centimetres.
• IV: Cancer has spread to the nearby lymph nodes and organs much beyond the primary tumour site. It is also larger than 3 centimetres.

Apart from this, the melanoma skin cancer stages include:

• 0: When cancer has not penetrated below the epidermis.
• I: Penetration to the dermis might occur, but cancer remains smaller in size.
• II: The spread of cancer has not occurred beyond the primary tumour site, but it has grown bigger, thicker and might show other signs like scaling, bleeding, or flaking.
• III: Cancer has spread to the lymph nodes or nearby skins or tissues.
• IV: This is the most advanced stage where cancer has spread to the distant organs and tissues beyond the primary site.

Also, it is important to note that skin cancers can recur at any point in time. Therefore, it is essential to carry on follow-up care and self-examinations.

Physicians carry out skin cancer diagnoses by doing various examinations and tests. A skin biopsy confirms the presence of cancer. During a biopsy, the tumour region is numbed with a local anaesthetic like lidocaine. Then a small portion of the tumour is sliced away and sent to the pathologists for examination. 

Therefore, in case an individual misses out on any obvious symptoms of skin cancer, a diagnostic test will give accurate results.

With the advancement in modern science, scientists discovered several cancer treatments. However, the treatment depends on the severity, type, and size of the tumour and the patient's overall health. Here are some effective means of cancer treatment:

• Topical Medicines: For basal cell carcinoma, one can apply ointments and gels superficially to the affected area. These medicines will stimulate the body's immune system to produce interferon that attacks cancer cells. Some people might experience side effects like skin redness, irritation etc. Although these medicines are effective for superficial cancers, they are not applicable to those parts from where the tumour has been removed.
• Destruction by EDC (Electrodesiccation and Curettage): This fast and inexpensive method involves scraping the tumour region repeatedly with a curette and cauterising its edge with an electric needle. However, this procedure leaves a scar, and the chances of recurrence are as high as 15%.
• Surgical Excision: This treatment has a 90% cure rate as it wholly removes the tumour by surgery and closes the wound edges with sutures. This procedure is much more expensive than the EDC.
• Mohs Micrographic Surgery: In certain skin cancers, the tumour margin is not defining, and normal cell preservation is crucial to maintain. For such a scenario, opting for this surgery is wise as it removes the tumour completely, and the re-examination of margins takes place to detect any residual cancer cells. However, this is a more complicated and expensive procedure.
• Radiation Therapy: This treatment does not involve any cutting and removes cancerous cells effectively. The biggest disadvantage of this treatment is that it affects the normal cells and the cancerous cells. Therefore, one cannot test the radiation area to ensure the tumour is fully removed. Also, the radiation scars look worse with time.

Other types of treatment include photodynamic therapy (PDT), laser surgery, oral medications and more.

However, it is advisable to know how to avoid skin cancer and follow the strategies to save huge costs in future and lead a healthy life.

It is vital to take some preventive measures that can lower the chances of skin cancer. These measures are as follows:

• Stop using tanning beds and sun lamps.
• Avoiding exposure to direct sunlight, staying indoors during the peak hours.
• Application of sunscreen with a high SPF (Sun Protection Factor).
• Wearing the right clothes and accessories offers maximum protection against sun rays.
• Examining the body for any abnormal growth or colouration.

Even after taking these measures, one might notice symptoms of skin cancer. In that case, he should consult a doctor urgently to treat the disease from an early stage.

Finally, let's consider the risk factors of skin cancer.

Here are the common risk factors of this disease:

• UV exposure from the sun or tanning beds. Fair-skinned individuals are more vulnerable due to less melanin.
• Immunosuppressed individuals. One suffering from HIV.
• Exposure to cancer-causing chemicals like arsenic, X-rays, etc
• Individuals suffering from sexually acquired wart virus infections.
• Existing skin cancer patients.
• Older people.

Therefore, from the mentioned points, it is evident that learning about treatment, types, causes and symptoms of skin cancer will help an individual fight against the disease effectively.