New Test Helps Unmask Melanoma
March 9, 2000 (Atlanta) -- A new test to help identify melanoma -- the
deadliest and most common form of skin cancer -- will someday be available to
labs across the country, according to a presentation at the annual meeting of
the International Society of Dermatopathology. The test detects abnormalities
that researchers at the University of California, San Francisco (UCSF), have
linked with melanoma.
Melanoma is so deadly because it has the ability to spread to other parts of
the body. In the U.S. in 1999, over 7,000 people died from the disease, making
it the ninth most common cancer. It can be cured if it is diagnosed and treated
early, before spreading.
Melanomas usually arise from moles. These moles have suddenly or gradually
become larger or irregular, or have changed color or shape. Despite these
changes, it is sometimes difficult for physicians to differentiate a benign, or
harmless, mole from a dangerous one. This delays accurate diagnosis and
At the meeting, Philip LeBoit, MD, a professor of pathology at UCSF,
presented summaries of two papers. The papers discuss a new technique that may
one day help pathologists -- doctors who work in labs diagnosing diseases --
more accurately diagnose melanoma.
"This [new diagnostic technique] is how melanoma diagnosis will be made
in the 21st century," LeBoit tells WebMD. Called comparative genomic
hybridization (CGH), the test was developed by co-author Dan Pinkel, PhD, a
professor at UCSF's Comprehensive Cancer Center. "When we began applying
it, we found pretty clear-cut results," says LeBoit. "It will be
especially useful in the hardest-to-diagnose cases -- those 5% of melanoma
cases that even top pathologists can't distinguish from non-cancerous under the
In their study, researchers analyzed 100 samples of diagnosed melanoma
cases. Using CGH, they found that all but one had detectable abnormalities.
Most tumors had two, three, or four of the abnormalities, says LeBoit. CGH
works by using fluorescent dyes to identify changes in cancer cell chromosomes.
Chromosomes are parts of genes, the "building blocks" of the body.
In another study using CGH, researchers did not find these same
abnormalities in benign moles. They conclude that pathologists can use these
abnormalities as markers for melanoma.
Such cases are nerve-wracking for pathologists -- and especially for
patients, says LeBoit. "They are told that the three biggest labs don't
agree and all we can do is say that you may have potentially lethal disease or
you might not. They have to live with this cloud over them. ... It's very
difficult to plan your life with a diagnosis like that," he says.
Right now, the test is currently too sophisticated and time-consuming to be
performed in labs across the country. "The problem is that right now it
costs $1,000 in staff and materials and months of work to get results. Only two
labs in the country can even do it," says LeBoit. Researchers are
developing a simpler technique that will hopefully be available within the next