For centuries pathologists have relied on the microscopic examination of tumors to distinguish between atypical moles and melanoma. By analyzing the level of proteins within mole cells, mass spectrometry can aid in the diagnosis of atypical moles. In this study, mass spectrometry correlated better than the gold standard of histologic examination to determine if an atypical mole was in fact benign or a melanoma. Early diagnosis of melanoma is critical to cure and long term survival.
San Jose, California, August 29, 2016 (Newswire.com) – California Skin Institute — A recently developed test for assessing suspicious moles for melanoma is more accurate than standard analyses, according to Dr. Rossitza Lazova, a former Yale investigator. The test, which analyzes proteins in cells, could provide more reliable results for clinicians with patients who might be at risk for this deadly cancer.
The study was published on August 5th in the Journal of the American Academy of Dermatology.
Melanoma is one of the most common forms of cancer and the most serious type of skin cancer. The gold standard for diagnosing melanoma is skin biopsy followed by microscopic examination of sampled tissue. However, in up to 1 in 4 cases, the results are inconclusive.
For the study, a former associate professor of Dermatology and Pathology at Yale University, Rossitza Lazova, M.D., collaborated with a national and international team of researchers to determine whether atypical moles could be more accurately diagnosed as either benign or cancerous (melanoma) using imaging mass spectrometry (IMS) — a technology that enables pathologists to focus in on individual proteins within sampled skin cells. In a prior study, the researchers used IMS to identify a molecular signature comprised of five proteins to differentiate between one type of benign mole and melanoma.
The research team retrospectively analyzed more than 100 cases of atypical moles. They compared results from IMS diagnosis to results based on standard microscopic examination of biopsies and correlated them with clinical outcomes.
The researchers found that in nearly all cases, the IMS analysis was a more accurate predictor, both of benign lesions and melanomas, than standard microscopic examination.
“Instead of pathologists being dependent solely upon the physical appearance of the cells, they now have the additional advantage of molecular information regarding the protein makeup [of cells] provided by mass spec imaging,” said Dr. Lazova, who is corresponding author on the study. “This test integrates anatomic pathology and analytical chemistry in a very useful and meaningful way.”
The finding suggests that IMS analysis, based on proteomic signatures, may improve both diagnosis and prediction of outcomes for patients with ambiguous moles, the researchers said.
Other authors include Erin H. Seeley, Heinz Kutzner, Richard A. Scolyer, Glynis Scott, Lorenzo Cerroni, Isabella Fried, Milena E. Kozovska, Arlene S. Rosenberg, Victor G. Prieto, Bahig M. Shehata, Megan M. Durham, Gina Henry, Jose L. Rodriguez-Peralto, Erica Riveiro-Falkenbach, Jochen T. Schaefer, Richard Danialan, Sylvie Fraitag, Sonja Vollenweider-Roten, Alireza Sepehr, Martin Sangueza, Nouf Hijazi, Yamile Corredoira, Rachel Kowal, Olga M. Harris, Francisco Bravo, Alan S. Boyd, Ralitza Gueorguieva, and Richard M. Caprioli.
The study was supported in part by a grant from the National Institutes of Health.
Dr. Lazova is currently the Director of Dermatopathology at California Skin Institute in San Jose, California.
This news release from a large dermatology practice plugs a study asserting that imaging mass spectrometry (IMS) — a procedure that involves ionizing a tumor sample in order to identify its protein content — does a better job at determining whether a certain type of atypical mole is benign or a potentially fatal melanoma than the standard practice of examining the tissue under a microscope. The study, authored in part by the practice’s director of dermatopathology, was published in the Journal of the American Academy of Dermatology. The news release does not give data to quantify how well IMS diagnoses skin tumors or compares with an old-fashioned microscope. Nor does it discuss costs, availability, or study limitations. As a result, it’s difficult to assess how much this technology could help patients.
A Spitz tumor is an uncommon skin lesion that usually occurs in children and young adults. It’s benign, but in some cases difficult to distinguish from a malignant melanoma. Moles that are impossible to classify are called “atypical Spitzoid neoplasms,” or ASMs. They often turn out to be benign but present a dilemma for patients and physicians because it’s unclear whether they should be treated. Developing an accurate test for these tumors would reduce anxiety and unnecessary treatments. Better diagnosis methods in order to “prevent aggressive surgical treatment in children and young adults” is an aim of the Yale School of Medicine’s Spitzoid Neoplasm Repository, which was a key player in the study. That’s a laudable goal that IMS might help to achieve.
The news release does not say how much IMS costs or how it compares with using a microscope. According to an article posted by the American Association for Clinical Chemistry, most mass spectrometry methods “require labor-intensive—and hence costly—sample preparation. Other factors include limited sample counts over which to amortize fixed expenses, and the fact that expertise for maintenance and assay development may be in short supply.”
A report on a diagnostic procedure should at the very least tell readers the proportion of patients with disease who tested positive (sensitivity) and the proportion of patients without disease who tested negative (specificity). Neither the news release nor the study on which it’s based offer these numbers.
In fact, there are no figures in the news release summarizing the accuracy of IMS in diagnosing the 102 ambiguous tumors included in the study, or comparing it with the accuracy of using a microscope. In each case, the initial diagnosis with a microscope was compared to a diagnosis of the same tumor with IMS and the patient’s clinical outcomes. According to our review of the study data, IMS correctly identified as benign 38 tumors that had been classified as ASM, or indeterminate, when previously examined under a microscope.
The news release offers this quote from a researcher: “Instead of pathologists being dependent solely upon the physical appearance of the cells, they now have the additional advantage of molecular information regarding the protein makeup (of cells) provided by mass spec imaging. … This test integrates anatomic pathology and analytical chemistry in a very useful and meaningful way.”
If it’s useful and meaningful, there should be data showing how. In addition, even some reporters without a strong grasp of statistics may have difficulty gleaning the numbers from the published manuscript. That makes it even more important to include reliable data in a news release.
The news release does not mention potential harms. Like any diagnostic or screening test, IMS carries a risk of a false negative and false-positive tests that could lead to a false sense of security or anxiety/unnecessary treatment. In addition, a biopsy is required to test a tissue sample (for both a standard evaluation and IMS). Though generally safe, a biopsy can result in scarring, bleeding, infection or allergic reaction to a topical antibiotic. The release could have mentioned these potential harms.
The news release does not address potential study limitations, including whether the sample size was great enough to show statistically significant differences between IMS and a microscope for all types of cases.
The release states that IMS “was a more accurate predictor, both of benign lesions and melanomas.” But in fact both methods did similarly well in finding the small number of actual melanoma cases. In four cases, patients developed cancer that spread to other organs or lymph nodes, and all were correctly identified as melanoma by both a microscope and IMS. In four other cases, patients developed disease that healed and did not spread. In three of those cases, the different diagnostic methods arrived at the same conclusions.
The study itself does not address potential limitations. We wonder whether the use of microscopic tissue exams from labs in 11 different countries going back several years accurately reflects the accuracy of current U.S. diagnostic methods. Also, it’s unclear how accurate IMS would be in clinical practice versus in this study. It could be that more study is needed to determine whether IMS should be widely adopted in the analysis of atypical moles.
The news release correctly states that melanoma “is one of the most common forms of cancer and the most serious type of skin cancer.” According to the National Cancer Institute, 76,380 cases are expected in the U.S. this year, with 10,130 deaths. The news release could have helped readers understand the significance of this test better by giving readers an idea of how many people have moles that are difficult to diagnose.
The news release states that the study was “supported” in part by the National Institutes of Health. However, neither the news release nor the study explains where other funding was obtained. The news release does not say whether any of the researchers had conflicts of interest, although no conflicts of interest were declared in the study.
The news release mentions the current standard of practice but does not offer a data-based comparison, as we note in the “quality of evidence section.”
While IMS use is growing in different fields of medicine, the news release doesn’t explain how accessible it is. Can a patient request one from their local dermatologist? Would most dermatologists know how to interpret the test results? The news release makes no attempt to inform us.
The news release does not exaggerate the novelty of this test. However, it could have clarified its description of mass imaging spectrometry to analyze moles as a “recently developed test.” Mass imaging spectrometry has been around since the 1960s, but it’s only recently been used to analyze moles.
The news release does not use sensational language.