CHICAGO – One in four patients with an invasive spitzoid melanoma died from melanoma within 10 years of diagnosis, according to a large SEER database analysis.
The risk of death due to melanoma increased significantly with tumor thickness, metastatic disease, head and neck lesions, male sex, and older age, Dr. Sultan Mirza reported at the annual meeting of the American Society for Dermatologic Surgery.
Spitzoid tumors represent a group of melanocytic neoplasms composed of distinct epithelioid and/or spindle cells and are important because of their mimicry of malignant melanoma.
Although there is a paucity of data, several smaller studies have suggested spitzoid melanomas are less aggressive and have a lower mortality rate when compared with conventional malignant melanoma, he said.
“Our study found spitzoid melanoma–specific mortality to be quite high and is likely to be more on par with the mortality of the conventional malignant melanoma,” Dr. Mirza of Mayo Clinic, Rochester, Minn., said in an interview.
“Given a lack of broadly accepted and well-defined diagnostic criteria, it is our suspicion that many cases of these tumors go unrecognized or are classified under various other types of neoplastic proliferations at the time of diagnosis. This, therefore, hinders our knowledge of the true prognosis of the spitzoid tumors.”
Using the National Cancer Institute’s SEER (Surveillance, Epidemiology, and End Results) database, the investigators identified 2,025 patients who were diagnosed between 1992 and 2010 with an epithelioid/spindle cell melanoma, epithelial cell melanoma, spindle cell melanoma not otherwise specified, or spindle cell melanoma type A or type B. After excluding patients with missing data including microscopic confirmation of malignancy or cause of death, 1,997 patients remained.
Most were white (96%), male (61%), and had invasive disease (98%). Their average age at diagnosis was 64 years, with 21 patients younger than 18 years of age. Median follow-up was 5.6 years.
Of the 1,997 patients, 773 (39%) were deceased at last follow-up. Of these, 331 (43%) died due to metastatic melanoma, Dr. Mirza said. The median time to death was 1.8 years after diagnosis.
Among the 1,956 patients with invasive disease, melanoma cause-specific survival at years 1, 5, 10, and 15 was 95%, 81%, 76%, and 74%, respectively.
Among 41 patients with in situ spitzoid melanoma, the melanoma cause-specific survival was 100% at years 1, 5, and 10.In survival analyses, a Breslow tumor depth of more than 4 mm carried a five times higher risk of melanoma-specific death than a depth of less than 1 mm (hazard ratio, 5.0; P less than .001), Dr. Mirza said.
The risk of death from melanoma increased dramatically as the stage of melanoma advanced from localized (referent) to regional (HR, 4.3; P = .001) and then to distant (HR, 19.4; P = .001).
A similar pattern was observed as patient age increased from 52 years or younger (referent) to 53-66 years (HR, 1.7; P = .001), 67- 77 years (HR, 1.7; P = .001), and finally to age 78 years and older (HR, 2.6; P = .001).
Men were twice as likely to die from melanoma as women (HR, 1.9; P = .001), he said.
The worst anatomic site for a lesion was on the head and scalp, which carried more than twice the risk of melanoma-specific death as lesions on the face and ears (HR, 2.3; P = .001).Limitations of the study were the lack of fluorescence in situ hybridization data, an inability to review and categorize tumor pathology, and confusing terminology regarding spitzoid tumors in the database, resulting in possible inclusion of other types of melanomas, Dr. Mirza said.
This variance of terminology emphasizes the need for standardized nomenclature and once accomplished, will hopefully provide further clarity regarding types of spitzoid growths, so we can know the true prognosis and treatment, he added.