Melanoma

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Melanoma ( also called malignant melanoma) is a form skin cancer that begins with melanocytes, the cells that produce melanin. Melanin is responsible for producing the pigment of the skin, hair and eyes, and plays a protective role against sun rays. Melanoma makes up just 4% of all skin cancer cases, but causes 74% of deaths related to skin cancer worldwide. Thus, melanoma is often called the deadliest type of skin cancer.

Contents

Risk factors

  • Race. Melanoma is more frequent among Caucasians with fair-colored skin and unusual among Asians including Filipinos. But African Americans or Hispanics diagnosed with melanoma have higher risks of mortality.
  • Gender. Men are more predisposed to melanoma than women.
  • Fair skin. People with fair skin or light-colored hair have less melanin. Consequently, they easily get sunburned and are more prone to developing melanoma.
  • Ultraviolet exposure. Frequent and excessive exposure to the ultraviolet rays of the sun, specifically during the first 10 to 18 years of life, is associated with melanoma. Ultraviolet rays from tanning beds are also implicated in the development of melanoma. People living near the equator, where the sun rays are more direct and intense, are at higher risk for melanoma.
  • Numerous or unusual nevi (moles). Having more than 50 moles on the body creates a risk for melanoma. Having one dysplastic nevi, an unsusual mole with a diameter greater than 5 millimeters and an irregular border, increases the risk for melanoma by two-folds.
  • Family history of melanoma. Ten percent (10%) of melanoma patients have a family history of the disease.
  • Personal history of melanoma. A study shows that about 8% of melanoma patients experience recurrence within the first two years after first diagnosis.
  • Compromised immune system. People suffering from diseases that weaken the immune system, such as HIV/AIDS and lymphoma, as well as those who are taking immunosuppresants, have greater risk for melanoma.

Symptoms

The Skin Cancer Foundation has the “ABCDE” guide for recognizing melanoma at its early stage. Having one or more of these signs warrants a consultation with the doctor.

  • A: Asymmetry. Two halves of the mole do not match each other.
  • B: Border. The edges of the mole are uneven and irregular.
  • C: Color. Varying shades of brown, black or gray, as well as the appearance of reddish or bluish tints, are warning signs.
  • D: Diameter. Melanomas are usually larger than the diameter of a pencil eraser (greater than 5 millimeter).
  • E: Evolving. Moles that change in color, size or shape are danger signs.

These changes are commonly observed in the torso, upper back, lower legs, head, and neck.

Types

  • Superficial spreading melanoma is the most common type, making up about 70% of all cases. Lesions are commonly found on the trunk for males, on the lower extremities for females, and the upper back for both sexes. The melanoma begins on the epidermis as flat or slightly raised lesions with irregular border and varying shades of of blue, red, purple, brown or black. The earliest sign of superficial spreading melanoma is a change in shape or color of an existing mole. The lesions remain superficial for several months or years before penetrating deeper into the skin. With early detection and treatment, five-year survival rate is around 95%.
  • Nodular melanoma accounts for 15 to 30% of all melanomas. The dome-shaped nodules may be black or brown in color, grows vertically with quick metastasis. Nodular melanoma affects men twice more than women, and may appear on the trunk or the head and neck.
  • Lentigo maligna melanoma makes up about 5% of melanomas and begins with lentigo, commonly called as sunspots or age spots that are associated with sun exposure. It is characterized by large, flat tan-colored lesions with irregular borders on the face or other sun-exposed skin. Growth is often gradual and may take as long as 50 years before lesions become invasive. Lentigo maligna melanoma occurs more commonly in women and during the 7th decade.
  • Acral lentiginous melanoma is the most common type among Asians and African Americans, though only making up about 5% of melanoma cases. Lesions on the palms, soles, oral mucosa and nailbeds often begin flat, but quickly become raised and metastasize to other organs.

Diagnosis

A dermatologist or an oncologist usually diagnoses melanoma based on patient history, physical examination and a series of tests.

Histopathologic examination of skin or mucosal lesions is the primary standard for diagnosis. A complete tissue excision biopsy is most commonly done, which will demontrate the depth of the tumor and the presence of ulceration.

A sentinel lymph node biopsy (SLNB) is done for pathologic staging when the primary lesion has a depth of 1 millimeter or more.

Other diagnostic tests include: blood test for tumor marker lactate dehydrogenase (LDH), an enzyme which is elevated in the blood when there is extensive organ damage, indicative of metastasis; imaging studies such as chest x-ray, and MRI (magnetic resonance imaging), CT (computed tomography), or PET (positron emission tomography) scans.

Staging

Staging of melanoma is dependent on diagnostic findings that demonstrate the following:

  • Size of growth
  • Depth of growth
  • Spread of disease (metastasis)

Stages of melanoma:

  • Stage 0: The cancer remains on the top layer of the skin (melanoma in situ).
  • Stage I: The growth is less than 2 millimeters deep.
  • Stage II: The growth is more than 2 millimeters deep.
  • Stage III: The cancer cells have spread below the skin to nearby bones, cartilage, muscles or lymph nodes.
  • Stage IV: The cancer cells have spread to other organs.

Treatment

  • Surgery. Surgical removal by excision is the first step in treatment of melanoma, especially for in situ cases. The extent of excision beyond the lesion border into normal skin, called margin, is determined by the depth of the lesion. In situ melanoma require about 5millimeters of surgical margin, while lesions with 1 millimeter depth require 1 centimeter margins. Two-centimeter margins are recommended for Stage II melanomas. Sentinel lymph node biopsy may also be done to prevent spread into the lymph nodes.

Surgical removal of lesions and lymph nodes is often done for Stage III melanoma.

  • Medication. For facial melanoma, doctors may prescribe imiquimod, a cream that is applied on lesions twice a week for several months. A new breakthrough in medical treatment of advanced melanoma is an oral drug called PLX4032. Although still in its third clinical trial phase, PLX4032 seems to be a promising drug. Initial studies showed it is effective for melanoma patients with the BRAF genetic mutation, with 81% of patients responding well.
  • Adjuvant therapy. Treatment interventions after surgical removal of melanoma include:
    • Chemotherapy with dacarbazine, tamoxifen and temolozomide in Stage IV, although regrowth may occur within three to six months. Anti-angiogenic drugs like angiostatin and endostatin, which cut off blood supply to cancer cells by preventing growth of new blood vessels, are being studied.
    • Immunotherapy with Interferon alpha-2b or interleukin-2;
    • Biotherapy, a combination of immunotherapy and chemotherapy;
    • Vaccine therapy, an experimental treatment approach where a vaccine is prepared from the patient's own cancer cells.
    • Radiation therapy, rarely used for melanoma but may be recommended in cases of metastasis to other organs.

Follow-up

The five- and ten-year survival rates can be as high as 100% for in situ melanoma, especially with early detection and treatment. However, melanoma may recur even after apparent succesful treatment. Follow-up with the doctor are usually scheduled every three to six months for physical examination, chest x-ray, blood tests and imaging scans (for more advanced cases). The patient should also regularly conduct self-checks and watch for the “ABCDE” signs.

Prevention

Practicing skin protection is the best measure for melanoma prevention.

  1. Avoid deliberate tanning under the sun or tanning beds.
  2. Liberally apply sunscreen with at least Sun Protection Factor (SPF) 30 prior to sun exposure. Sunscreens should ideally provide protection against ultraviolet A (UVA) and ultraviolet B (UVB) rays. Apply sunscreen on dry skin 15 to 30 minutes before exposure, and reapply after sweating or being in water. Sunscreens do not make sun-tanning any safer.
  3. Wear protective clothing such as long sleeves and pants, and gear such as wide-brimmed hats and sunglasses.
  4. Avoid sun exposure between 10 AM and 4 PM. Schedule outdoor activities before or after these periods of time.
  5. Checking the body for unusual moles or pigmentation using the “ABCDE” guide is best done around the time of your birthday every year.


References