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VIDEO: Gene test guides need for sentinel node biopsy in elderly melanoma patients



SAN DIEGO – The results of a gene expression test, along with tumor thickness and patient age, can guide the need for sentinel lymph node biopsy, based on results from more than1,400 consecutively tested patients from 26 U.S. surgical oncology, medical oncology and dermatologic practices.

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The findings, presented by John Vetto, MD, at the annual meeting of the American Academy of Dermatology, indicate the DecisionDx test correctly identified patients aged 65 and older with T1-T2 tumors whose risk of sentinel node metastasis was lower than 5%. The most recent melanoma guidelines from the National Comprehensive Cancer Network recommend that clinicians “discuss and offer” sentinel node biopsy if a patient has a greater than 10% likelihood of a positive node. If the likelihood is 5%-10%, the recommendation is to “discuss and consider” the procedure. But if the likelihood of a positive node is less than 5%, the guidelines recommend against a biopsy.

“Sentinel node biopsy (has) risks, especially in medically compromised older patients,” Dr. Vetto, professor of surgery at the Oregon Health and Sciences University, Portland, said in an interview, in which he discussed clinical use of the test. “This test offers us a good way to assess the risk/benefit ratio so we can better care for patients, and follow the newest guidelines about sentinel node biopsy.”

The DecisionDx Melanoma, developed by Castle Biosciences, tests for the expression of 28 genes know to play a role in melanoma metastasis, and three control genes. Tumors are stratified either as Class 1, with a 3% chance of spreading within 5 years, or Class 2, with a 69% risk of metastasis. There are two subclasses: 1A, which has an extremely low risk of progression, and 2b, which has an extremely high risk of progression.

For patients with T1-T2 tumors who had a Class 1A test result (lowest risk of recurrence), SLN positivity was 4.6% for all ages, 2.8% in patients 55 years and older, and 1.6% in patients 65 years and older. For patients with T1-T2 tumors who had a Class 2B test result (highest risk of recurrence), SLN positivity was 18.8% for all ages, 16.4% in patients 55 years and older and 11.9% in patients 65 years and older.

Dr. Vetto is a paid speaker for Castle Biosciences.

SOURCE: Vetto et al. AAD 2018 late-breaking research, Abstract 6805

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