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Malignant melanoma (MM)
has become an important public health problem. This year, in the United
Slates, it is estimated that there will be 51,400 new cases of this
cancer.
 The
rate of MM is currently rising faster than that of any other cancer.
In 1935, the lifetime risk of an individual in the U.S. developing melanoma
was one in 1,500. By 1980, the risk had increased to one in 250 and
in 2001, the risk is one in 71. In other words, the risk of developing
MM has more than doubled in the past decade and increased more than
20-fold over the past half century. It is projected that the risk will
rise to one in 50 by the year 2010.
Malignant melanoma can be
lethal. Although MM accounts for only 5% of all skin cancers, it causes
more than 3/4 of deaths from skin cancer. This year, 7,800 Americans
will die of this disease. Although the development of skin cancer is
often thought to be associated with increasing age, that is no longer
the case with melanoma. About one in four persons who develop it now
is under the age of 40. The rate is increasing particularly rapidly
in younger women. In fact, MM is now the most frequent cancer in women
in the U.S., aged 25-29, and the second most frequent (after breast
cancer) for women of 30-34. More than 20% of these tumors appear on
the head and neck.
Multiple factors have been
suggested as influencing the risk of developing melanoma. In an analysis
of 43 potential risk factors in 200 persons with MM compared with controls
(persons similar to the others, except that they do not have melanoma),
six key factors producing greater susceptibility to the disease have
been noted:
- Red/blond hair, blue/green
eyes, and a very fair complexion.
- Family history of MM.
Anyone with a first-degree family member (parent, sibling, or child)
with the disease has a 50% chance of inheriting the melanoma gene.
- Actinic keratosis, a
precancer that arises on the skin surface as a result of sun exposure
- Marked freckling of the
upper back.
- Three or more blistering
sunburns prior to age 20. Sunburns are most damaging when they occur
early in life.
- Outdoor summer jobs for
three or more years during the teen years.
Having any one or two of
these factors increased a person's risk for developing MM three to four
times. Having three or more of these factors elevated the risk almost
20-fold. Numerous moles, frequently atypical in appearance, also increase
risk, as does intermittent sun exposure. A high-risk subset of the population
can be easily clinically identified using this model so that educational
and surveillance efforts can be effectively focused.
Malignant melanoma is a
lethal cancer but is not uniformly fatal. In the U.S., survival has
improved from 40% in the 1940's to 85% by the late 1980`s.
The factors that best predict
survival in persons with MM is the thickness of the primary lesion.
Persons with lesions less than 0.75 mm in thickness have almost a 100%
survival rate, while only half of those with lesions greater than 3
mm will live. Therefore, early detection of melanoma by the identification
of suspicious lesions is critical.
The easiest way to recognize
the early warning signs is by remembering the "ABCD" rule:
A = Asymmetry - the two sides do not match
B = Border - irregular shape
C = Color - a variety of shades
D = Diameter - > 6 mm, the size of a pencil eraser.
Other factors have also
been found useful in predicting outcome. Clinical stage, anatomic site
and ulceration all have statistically significant prognostic value.
A number of studies have suggested that age, gender and metastatic activity
influence survival. Newer data suggest that immunologic factors and
tumor volume may turn out to he better predictors of survival than the
above factors.
The rising rate of MM reflects
damage to the skin that has been done by the sun in the past. If a difference
is going to be seen prospectively, we must use protection (sunscreens
with an SPF of 15 or greater, clothing, and shade) and have suspicious
areas evaluated early in their course so that melanoma can be treated
when curable.
Until further research yields
a cure for advanced melanoma, sun protection and early detection remain
the first line of defense in the fight against this cancer.
Darrell S.
Rigel, MD is Clinical Professor, New York University Medical Center,
a past-President of the American Academy of Dermatology, and a member
of the Foundation's Medical Council.
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