MELANOMA SKIN CANCER OVERVIEW

 

 

What Is Melanoma Skin Cancer?

 Skin cancers are divided into two major groups due to their characteristic behaviors: melanoma skin cancer and nonmelanoma skin cancer. We will be discussing Melanoma Skin Cancer in this article.Melanoma begins in the cells (melanocytes) that produce the skin coloring. Since Melanoma has relevance to abnormalities of skin, in order for us to better understand let us at first gather some useful information of normal skin.

Normal skin

The skin can be considered as the largest organ in the body. It covers and protects the organs inside the body. It also protects the body against germs and prevents the loss of too much water and other fluids. The skin sends messages to the brain about heat, cold, touch and pain. The skin has three layers. From the outside in, they are: the epidermis, the dermis, and the subcutis. The top layer of the skin is the epidermis. The epidermis is very thin and serves to protect the deeper layers of skin and the organs. The epidermis itself has three layers: upper, middle and    bottom layers composed of basal cells. These basal cells divide to form keratinocytes, (also called squamous cells) which make a substance (keratin) that helps protect the body.

Another type of cell, melanocytes, is also present in the epidermis. These cells produce the pigment called melanin. Melanin gives the tan or brown color to skin and helps protect the deeper layers of the skin from the harmful effects of the sun. A layer called the basement membrane separates the epidermis from the deeper layers of skin.  The middle layer of the skin    ‘dermis’ is much thicker than the epidermis. It contains hair shafts, sweat glands, blood vessels and nerves. ‘Subcutis’, the last and deepest layer of the skin keeps in heat and has a shock-absorbing effect that helps protect the body's organs from injury.

Melanoma skin cancers

Melanoma skin cancers begin in the melanocytes. Other names for this cancer include malignant melanoma and cutaneous melanoma. Because most cancerous melanoma cells continue to produce melanin, melanoma tumors are often brown or black. Melanoma is much less common than basal and squamous cell    skin cancers and it is mostly curable in its early stages. But it is more likely that melanoma can spread to the other parts of the body than basal or squamous cell cancer.

Melanoma most often appears on the trunk of fair-skinned men and on the lower legs of fair-skinned women, but it can appear in other places as well. Having darkly pigmented skin lowers the risk of melanoma but it does not mean that a person with dark skin will not develop melanoma. People with darker skin can have this cancer on the palms of the hands, soles of the feet and under the nails. Rarely, melanomas can occur   in parts of the body not covered by skin such as the eyes, mouth, vagina, large intestine and other internal organs.

What Causes Melanoma Skin Cancer?

A risk factor is anything that increases a person's chance of getting a disease such as cancer. Different cancers have different risk factors. For example, smoking is a risk factor for lung and other types of cancers. It is important to remember, however, that while these factors increase the risk, they do not necessarily cause the disease to develop. Many people with risk factors never develop cancer, while others with cancer have no known risk factors.

Risk Factors for Melanoma Skin Cancer

Moles: A mole (nevus) is a benign skin tumor. Moles are not usually present at birth, but begin to appear in children and teenagers. Having certain types of moles make a person more likely to develop melanoma. One type of mole that increases the risk of melanoma is called   “Dysplastic nevus” or atypical mole. Dysplastic nevi (nevi is the plural of nevus) looks   like normal moles, and a little like melanoma. (Please refer to the section that follows for descriptions of the appearance of moles and melanomas). They are often larger than other moles. People with lots of moles and those who have some large moles, have an increased risk for melanoma.

Fair skin: The risk of melanoma is about 20 times higher for people with white or fair skin than for those with darker skins. This is because the melanin of darker skin offers some protection.

Family history: The risk of melanoma is greater if one or more of a person's close relatives (mother, father, brother, sister, child) have been diagnosed with melanoma.

Immune suppression: People who have been treated with medicines that suppress the immune system, such as organ transplant patients, have an increased risk of developing melanoma.

 Over exposure to ultraviolet (UV) radiation. People with too much exposure to UV rays of sunlight or tanning light are at greater risk for all types of skin cancers, including melanoma.

Age: About half of all melanomas occur in people over the age of 50. However, young people (ages 20 to 30) can also have melanoma. In fact, melanoma is one of the most common cancers in people less than 30 years of age.

Can It Be Prevented?

The best way to lower the risk of melanoma is to avoid too much exposure to the sun especially during the middle of the day when the light is most intense and other sources of UV light. Protect yourself with clothing, sunglasses, and a hat with a broad brim. Use quality sunscreens with a sun protection factor (SPF) of 15 or more on exposed skin. People with fair skin who burn easily should be very careful to use sunscreen. People who have many moles should check them regularly to see if the moles have changed in shape/size. A dermatologist should also check them regularly as well.

How Early Is Melanoma Skin Cancer Detected?

Melanoma can be found early and both doctors and patients play important roles in finding skin cancer. Part of a routine checkup should include a skin examination atleast every three years for people between 20 and 40 years of age and every year for those aged 40 and more.

It's also important to have self-examination of your skin   once a month. You should know the pattern of moles, freckles and other marks on your skin so that you'll notice any changes. Spots on the skin that change in size, shape, or color, any unusual sore, lump, blemish, marking, or change in the way an area of the skin looks or feels could    be a sign of skin cancer and   should be seen by a doctor right away.

It's important to know the difference between melanoma and an ordinary mole. We can keep an eye on the difference between normal moles and melanoma. Watch for these possible signs of melanoma:

        One half of the mole does not match the other half.

        The edges of the mole are ragged or notched.

        The color of the mole is not the same all over. There may be shades of tan- brown or black and sometimes patches of red, blue or white.

        The mole is usually wider than about 1/4 inch

Skin biopsy

If the doctor thinks a melanoma might be present, he or she will take a sample of skin to examine under a microscope. This is called a skin biopsy. Different methods can be used for a skin biopsy. The choice depends on the size and location of the affected area. Any biopsy is likely to leave a scar. The skin around the area of the biopsy will be numbed before the biopsy. You will feel a small needle prick and a little burning with some pressure for less than a minute, but no pain.

Staging of medical findings

Staging is a process of finding out how widespread a cancer is. Staging includes describing the size of the cancer as well as whether it has spread to any other organs. The thinner the melanoma, the better the prognosis. In general, melanomas less than about 1/25 of an inch in depth (or the diameter of a period or a comma) have a very small chance of spreading. Be sure to ask your doctor to explain your stage in a way you understand. This will help you and your doctor decide on the best treatment for you. Survival rates by stage: The 5-year relative survival rate for stage I melanoma is over 90%. The 5-year relative survival rates of stages II and III are about 80% and 50%, respectively. About 20% to 30% of people with stage IV melanoma survive 5 years after diagnosis. The 5-year survival rate refers to the percent of patients who live at least 5 years after their cancer is found. Still many of these patients live much longer than 5 years.

How Is Melanoma Skin Cancer Treated?

There are four types of treatment for melanoma skin cancer: Surgery, Radiation, Chemo Therapy and Immuno Therapy. Each of these is explained below.

Surgery

Surgery to remove the melanoma is often the main treatment as long as the cancer is not spread to other distinct organs such as lungs and brain. Lymph nodes are sometimes checked for cancer during surgery. Thin melanomas can be completely cured by a minor operation called simple excision. The tumor is cut out, along with a small amount of normal skin at the edges. The wound is carefully stitched back together. This surgery will leave a scar. Sentinel node biopsy is another procedure. The doctor injects a small amount of a dye or tracer substance into the site of the melanoma. After about an hour, lymph nodes are checked to find which one is draining lymph fluid from the skin near the melanoma. When the correct lymph node, called the sentinel node, has been found, it will be removed and looked at under a microscope. If melanoma cells are found in this lymph node, the remaining lymph nodes in this area are removed. If the sentinel node does not contain melanoma cells, further lymph node surgery can be avoided. Because this type of biopsy is new, different doctors may disagree, about the timing of this method.

Chemotherapy

Chemo Therapy refers to the use of drugs to kill cancer cells. The drugs are given in the form of shots or pills. Once they enter the bloodstream they reach all parts of the body. The drugs attack cancer cells that have spread beyond the skin to the lymph nodes and other organs. Sometimes doctors prescribe Chemo Therapy after surgery to make sure any remaining cancer cells are destroyed.

Several types of Chemo Therapy can be used for stage IV melanoma. Although Chemo Therapy is usually not as effective in melanoma as in some other types of cancer, it may relieve symptoms or extend the life of some patients with stage IV melanoma. While Chemo Therapy drugs kill cancer cells, they also kill some normal cells, causing side effects. The exact side effects depend on the type of drugs used, the amount taken, and the length of treatment. Temporary side effects of Chemo Therapy might include nausea and vomiting, loss of appetite, loss of hair and mouth sores. Because Chemo Therapy can kill normal blood cells, patients may have low blood cell counts. These low counts increase the chance of infection, bleeding or bruising after minor cuts and fatigue. Most side effects disappear once treatment is stopped. One of the most effective chemotherapeutic agent towards skin melanoma is “Platinol” or Cisplatin”. However there are certain crucial rate limiting toxicities associated with Cisplatin. One of the breakthroughs to mitigate the toxicities of Cisplatin is the recent discovery of a novel chemoprotectant by BioNumerik Pharmaceuticals, San Antonio, TX, and USA bearing the code name of BNP7787. This highly promising clinical candidate by BioNumerik Pharma has already received the fast track approval from Food & Drug Administration Agency.   BNP7787 is at present undergoing phase III clinical trials in the United States exhibiting its astonishing results with a fast track approval for human use as a Chemoprotectant. Chemoprotectant is a novel class of therapeutic compounds that could reduce or eliminate the undesired toxicities exhibited by a chemotherapeutic agent.  In this particular case chemotherapeutic agent (cytotoxic agent) is the one that cures the cancer. A chemoprotectant is extremely useful in conjunction with the actual drug. For example the rate limiting toxicities of cisplatin is kidney failure. In conjunction with BNP7787 patients are currently receiving much higher doses of cisplatin with out suffering any damage to their kidney functions. Such higher doses could be lethal if the cytotoxic agent is given without the aid of a chemoprotectant.

Radiation Therapy

This treatment uses high-energy x-rays to kill cancer cells or slow down their rate of growth. One method can be even in the same way as the type of x-ray used to find a broken bone. The main role of Radiation Therapy for melanoma is to relieve symptoms if the cancer has spread to the brain. This type of radiation therapy is not expected to cure the cancer.

Immuno Therapy

Immuno Therapy is a type of treatment that helps a patient's immune system to find and destroy cancer cells. Immuno Therapy may be used by itself, but more often it is used along with another treatment. There are several types of Immuno Therapy for patients with advanced melanoma.  Cytokine therapy uses proteins that activate the immune system in a general way. Side effects of Cytokines may include fever, chills, aches and severe tiredness.

HARRY KOCHAT
BioNumerik Pharmaceuticals Inc.
(An oncology based company based in San Antonio, Texas, USA)


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