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Castle Biosciences to Present New Data Demonstrating DecisionDx®-Melanoma's Ability to Identify Patients with Greater Risk of Recurrence and Poor Outcomes Within Early-Stage Melanoma at EADO and ACMS

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Castle Biosciences (Nasdaq: CSTL) will present new DecisionDx-Melanoma data at EADO (Apr 23-25, 2026) and ACMS (Apr 30–May 3, 2026).

Multi-center and SEER population analyses show the 31-gene expression profile provides prognostic information beyond AJCC staging, identifying higher-risk patients among thin and early-stage melanoma who may benefit from intensified management.

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News Market Reaction – CSTL

-2.31%
1 alert
-2.31% News Effect

On the day this news was published, CSTL declined 2.31%, reflecting a moderate negative market reaction.

Data tracked by StockTitan Argus on the day of publication.

Key Figures

Multicenter cohort size: 1,817 patients Disease stages: Stage I–III CM Early-stage subset: Stage I–IIA +5 more
8 metrics
Multicenter cohort size 1,817 patients Stage I–III cutaneous melanoma cohort in EADO poster
Disease stages Stage I–III CM Patient stages evaluated for DecisionDx-Melanoma prognostic value
Early-stage subset Stage I–IIA Subset where biologically high-risk patients were identified
Tumor thickness T1a and T1b Thin melanoma population in SEER survival analysis
Outcome horizon 5-year recurrence risk Improved prediction when combining test with AJCC staging
Survival endpoint 5-year melanoma-specific survival Outcome stratified in SEER registry study
Gene signature size 31-gene expression profile DecisionDx-Melanoma test described in both posters
Conference dates April 23–25, 2026 EADO 2026 meeting in Prague for poster presentation

Market Reality Check

Price: $19.83 Vol: Volume 211,256 vs 20-day ...
normal vol
$19.83 Last Close
Volume Volume 211,256 vs 20-day average 286,202 (relative volume 0.74), showing no outsized trading interest. normal
Technical Shares at $25.16, trading below the 200-day MA of $28.20 and 43.18% under the 52-week high.

Peers on Argus

Peers show mixed moves: MYGN up 1.98%, NEO up 0.37%, while FLGT, CDNA, and PSNL ...

Peers show mixed moves: MYGN up 1.98%, NEO up 0.37%, while FLGT, CDNA, and PSNL are down, suggesting stock-specific factors for CSTL.

Historical Context

5 past events · Latest: Apr 15 (Neutral)
Pattern 5 events
Date Event Sentiment Move Catalyst
Apr 15 Earnings timing update Neutral +1.0% Announced date and webcast details for Q1 2026 results release.
Apr 10 Workplace recognition Positive -1.3% Received 2026 USA TODAY Top Workplaces USA Award for fifth consecutive year.
Mar 27 Clinical data poster Positive -4.7% Reported AAD 2026 SEER-linked data showing strong survival stratification by DecisionDx-Melanoma.
Mar 13 Prospective study results Positive +0.9% Future Oncology publication showing i31-SLNB identifies patients below NCCN 5% SLNB threshold.
Mar 09 Prospective SLNB study Positive -0.4% Largest multicenter study confirming 2.6% nodal positivity under 5% predicted risk.
Pattern Detected

Recent DecisionDx-Melanoma data updates have often been positive but met with modest or negative next-day price reactions.

Recent Company History

Over the past two months, Castle Biosciences has repeatedly highlighted DecisionDx-Melanoma data and operational milestones. On Mar 9 and Mar 13, prospective multicenter i31-SLNB studies showed low nodal positivity and strong three-year outcomes. On Mar 27, SEER-linked data again supported risk stratification benefits, yet the stock moved -4.74%. A workplace award on Apr 10 and an earnings-date notice on Apr 15 drew only modest price changes, suggesting limited immediate trading impact from non-financial news.

Market Pulse Summary

This announcement reinforces Castle Biosciences’ focus on DecisionDx-Melanoma, adding multi-center a...
Analysis

This announcement reinforces Castle Biosciences’ focus on DecisionDx-Melanoma, adding multi-center and SEER-based evidence that the 31-gene expression profile refines risk within early-stage cutaneous melanoma, including thin T1a and T1b tumors. In recent months, the company has repeatedly reported supportive clinical results across large cohorts and prospective studies. Investors may watch how these data translate into clinical adoption, reimbursement durability, and future revenue trends, alongside upcoming financial disclosures.

Key Terms

ajcc staging, national comprehensive cancer network, sentinel lymph node biopsy, 31-gene expression profile, +3 more
7 terms
ajcc staging medical
"whose recurrence and survival risk may be underestimated by American Joint Committee on Cancer (AJCC) staging alone"
AJCC staging is a standardized system doctors use to describe how advanced a cancer is by looking at tumor size, whether nearby lymph nodes are involved, and whether the cancer has spread to other parts of the body. For investors, staging matters because it helps predict likely outcomes and which treatments will be used or approved, affecting the potential market size, pricing, and timing for drugs, tests or devices—like knowing a play’s act to anticipate what comes next.
national comprehensive cancer network medical
"decisions consistent with National Comprehensive Cancer Network® guideline risk thresholds"
A coalition of major cancer centers and experts that develops widely used, evidence-based treatment guidelines for oncology care. Its recommendations act like a trusted rulebook or roadmap for doctors, insurers and hospitals, so updates can change which therapies get prescribed, reimbursed or adopted—making it an important influence on drug uptake, clinical trial value and healthcare company prospects.
sentinel lymph node biopsy medical
"including those related to sentinel lymph node biopsy and surveillance intensity"
A sentinel lymph node biopsy is a surgical procedure that removes and tests the first lymph node(s) that drain fluid from a tumor to see if cancer has spread. Think of it as checking the first security checkpoint after a breach; a negative result often means less extensive surgery and lower treatment costs, while a positive result can change therapy, prognosis, regulatory decisions and market demand for related diagnostics and treatments, making it important to investors.
31-gene expression profile medical
"The 31-gene expression profile test stratifies melanoma-specific survival among patients"
A 31-gene expression profile is a laboratory test that measures the activity levels of 31 specific genes in a patient’s tumor or tissue to predict how the disease is likely to behave. For investors, it matters because the test can change clinical decisions—identifying patients at higher or lower risk of recurrence—and thus influences demand, reimbursement, regulatory review, and the commercial value of companies that develop or sell the assay. Think of it like a weather forecast for a patient’s disease course: it helps clinicians and payers decide how aggressively to treat.
melanoma-specific survival medical
"stratifies melanoma-specific survival among patients with AJCC T1a and T1b cutaneous melanoma"
Melanoma-specific survival is the proportion of patients in a study or patient group who have not died from melanoma over a given period, ignoring deaths from other causes. Investors use it as a direct measure of a cancer treatment's ability to prevent death from that cancer, much like tracking how many boats finish a race without sinking; clearer, cancer-specific survival can signal a therapy's real clinical benefit and influence regulatory approval, market uptake, and long-term revenue prospects.
cutaneous melanoma medical
"refines risk assessment across patients with cutaneous melanoma (CM)"
A type of skin cancer that starts in pigment-producing cells and can grow into the deeper layers of the skin or spread to other organs if not treated. For investors, it matters because diagnosis rates, treatment options, regulatory approvals and long-term outcomes drive demand for drugs, diagnostics and medical services the same way a rising storm increases demand for shelters—successful therapies or tests can significantly affect revenues and stock values in healthcare-related businesses.
seer program registries medical
"ongoing collaboration leveraging data from the National Cancer Institute's SEER Program registries"
The SEER Program registries are a coordinated set of cancer databases that collect and track who is diagnosed with different cancers, how they are treated, and how long patients survive. Think of them as a nationwide census for cancer that gives comparable counts and trends over time; investors use this data to estimate the size of patient populations, gauge unmet medical needs, forecast demand for drugs or devices, and assess the commercial potential and regulatory context for oncology products.

AI-generated analysis. Not financial advice.

Multi-center clinical and population-based data show that DecisionDx-Melanoma identifies biologically high-risk patients—including those with thin and early-stage disease—and provides recurrence risk insights to guide more precise, risk-aligned clinical management

FRIENDSWOOD, Texas, April 21, 2026 /PRNewswire/ -- Castle Biosciences, Inc. (Nasdaq: CSTL), a company improving health through innovative tests that guide patient care, today announced it will present new data on its DecisionDx-Melanoma test addressing a critical clinical challenge in melanoma care: identifying which patients with early-stage disease are at risk for poor outcomes and may benefit from intensified management. The data will be presented at the 22nd European Congress of Dermato-Oncology (EADO) Congress and the American College of Mohs Surgery (ACMS) 58th Annual Meeting. 

The data to be presented at both meetings further demonstrate that DecisionDx-Melanoma provides clinically actionable, personalized information that refines risk assessment across patients with cutaneous melanoma (CM). Notably, the data show the test can identify patients with thin tumors and early-stage disease whose outcomes may be more consistent with higher-risk melanoma and whose recurrence and survival risk may be underestimated by American Joint Committee on Cancer (AJCC) staging alone, enabling more precise, risk-aligned clinical management. 

"Some of the most important melanoma treatment decisions are made early, when risk is often difficult to assess, underscoring the need to confidently escalate care or avoid unnecessary interventions," said Rebecca Critchley-Thorne, Ph.D., vice president, research and development, at Castle Biosciences. "These studies further demonstrate the ability of DecisionDx-Melanoma to identify patients who may be at greater risk than expected based on staging alone, while also providing individualized recurrence risk information to support more informed management decisions. This information complements traditional clinicopathologic factors and helps guide decisions consistent with National Comprehensive Cancer Network® guideline risk thresholds, including those related to sentinel lymph node biopsy and surveillance intensity." 

Details of the Company's poster at EADO, taking place in Prague, Czech Republic, from April 23-25, 2026, are as follows: 

  • Poster title: The 31-GEP provides personalized prognostic information beyond AJCC staging in patients with cutaneous melanoma 
  • Poster number: A-275 

At EADO, data are being presented from a large, multi‑center cohort of 1,817 patients with stage I–III CM that show DecisionDx‑Melanoma provides independent, personalized prognostic information beyond AJCC staging. In the study, the test significantly improved 5‑year recurrence risk prediction when combined with staging and identified biologically high‑risk patients within early‑stage disease (stage I–IIA). These patients had recurrence rates comparable to those with higher‑stage melanoma (stage IIB-IIIA), highlighting clinically meaningful differences in risk within early-stage disease that are not fully captured by traditional staging. These findings underscore the value of the DecisionDx-Melanoma test in supporting more precise, risk-aligned management decisions, including identifying patients who may benefit from closer surveillance or referral to multidisciplinary care teams.

Details of the Company's poster at ACMS, taking place in Austin, Texas, from April 30-May 3, 2026, are as follows: 

  • ePoster title: The 31-gene expression profile test stratifies melanoma-specific survival among patients with AJCC T1a and T1b cutaneous melanoma: A 5-year outcome SEER population study 

The study to be shared at ACMS analyzes population-based Surveillance, Epidemiology and End Results (SEER) registry data showing that DecisionDx‑Melanoma can provide prognostic insight beyond AJCC staging in patients with thin T1a and T1b CM. The test identified molecularly high‑risk T1 patients with significantly lower 5‑year melanoma‑specific survival and, when combined with staging, identified more patients who died from melanoma than a stage III classification alone. These findings support the use of DecisionDx-Melanoma to inform more precise, risk-aligned management in a population often considered low risk, including identifying patients who may otherwise go unrecognized as high risk and who may benefit from closer surveillance or more proactive management. This poster is also part of Castle's ongoing collaboration leveraging data from the National Cancer Institute's SEER Program registries. 

About DecisionDx-Melanoma 
DecisionDx-Melanoma is a gene expression profile (GEP) test designed to analyze tumor biology to deliver a personalized risk assessment for patients with stage I–III cutaneous melanoma, enhancing risk stratification beyond American Joint Committee on Cancer (AJCC) staging alone. By combining molecular insights with select clinicopathologic features, the test provides two distinct outputs: a personalized risk of sentinel lymph node (SLN) positivity and a personalized risk of recurrence and/or metastasis. This clinically actionable information is designed to help guide risk-aligned patient management decisions, including SLN biopsy consideration, follow-up intensity, imaging and referrals. 

DecisionDx-Melanoma is supported by 58 peer-reviewed publications, including prospective studies and meta-analyses, and was developed in collaboration with more than 100 leading U.S. institutions. The test has been clinically validated in more than 10,000 patient samples, ordered more than 230,000 times since launch, and has been shown to be associated with improved patient survival. Learn more at castlebiosciences.com/tests/prognostic/decisiondx-melanoma/overview.

About Castle Biosciences 
Castle Biosciences (Nasdaq: CSTL) is a leading diagnostics company improving health through innovative tests that guide patient care. With a primary focus in dermatologic and gastroenterological disease, we develop personalized, clinically actionable solutions that help improve disease management and patient outcomes. 

We put people first—empowering patients and clinicians and informing care decisions through rigorous science and advanced molecular tests that support more confident treatment planning. To learn more, visit www.CastleBiosciences.com and connect with us on LinkedIn, Instagram, Facebook and X.

DecisionDx-Melanoma, DecisionDx-CMSeq, i31-SLNB, i31-ROR, DecisionDx-SCC, MyPath Melanoma, AdvanceAD-Tx, TissueCypher, DecisionDx-UM, DecisionDx-PRAME and DecisionDx-UMSeq are trademarks of Castle Biosciences, Inc. 

Forward-Looking Statements 
This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, which are subject to the "safe harbor" created by those sections. These forward-looking statements include, but are not limited to, statements concerning: the ability of DecisionDx-Melanoma to (i) help clinicians more confidentlyescalate care for higher-risk patients while avoiding unnecessary interventions in those at lower risk of poor outcomes; (ii) identify patients at higher or lower risk than predicted by AJCC staging alone, including high-risk T1 (thin) tumors with mortality risk approaching that of thicker melanomas; (iii) support more personalized management decisions by delivering a personalized risk assessment; (iv) significantly improve recurrence risk prediction when combined with AJCC staging, including the identification of biologically high-risk patients within early-stage disease; and (v) provide information consistent with NCCN guideline risk thresholds, including with respect to sentinel lymph node biopsy and surveillance intensity decisions. The words "designed," "may," "can," "provides," "helps guide," and similar expressions are intended to identify forward intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements that we make. These forward-looking statements involve risks and uncertainties that could cause actual results to differ materially from those in the forward-looking statements, including, without limitation: subsequent study or trial results and findings may contradict earlier study or trial results and findings or may not support the results obtained in these studies, including with respect to the discussion of our tests in this press release; actual application of our tests may not provide the aforementioned benefits to certain patients; and the risks set forth under the heading "Risk Factors" in our Annual Report on Form 10-K for the year ended December 31, 2025, and our subsequent Quarterly Reports on Form 10-Q, each as filed or to be filed with the SEC, and in our other filings with the SEC. The forward-looking statements are applicable only as of the date on which they are made, and we do not assume any obligation to update any forward-looking statements, except as may be required by law.

Cision View original content to download multimedia:https://www.prnewswire.com/news-releases/castle-biosciences-to-present-new-data-demonstrating-decisiondx-melanomas-ability-to-identify-patients-with-greater-risk-of-recurrence-and-poor-outcomes-within-early-stage-melanoma-at-eado-and-acms-302747617.html

SOURCE Castle Biosciences, Inc.

FAQ

What new DecisionDx-Melanoma data is Castle Biosciences (CSTL) presenting at EADO April 2026?

The EADO poster reports a 1,817-patient multi-center cohort where DecisionDx-Melanoma improved 5-year recurrence prediction beyond AJCC staging. According to the company, the test identified biologically high-risk patients within stage I–IIA whose recurrence rates matched higher-stage disease.

How does the DecisionDx-Melanoma test stratify risk for T1a and T1b patients in the ACMS April–May 2026 presentation?

The ACMS SEER analysis shows the 31-gene test identifies molecularly high-risk T1a/T1b patients with significantly lower 5-year melanoma-specific survival. According to the company, combining the test with staging found more melanoma deaths than stage III classification alone.

Does DecisionDx-Melanoma provide information beyond AJCC staging for early-stage melanoma (CSTL)?

Yes. The company says DecisionDx-Melanoma gives independent, personalized prognostic information beyond AJCC staging for stage I–III patients. This can reveal high-risk biology in early-stage tumors and refine recurrence risk to guide management decisions.

How might DecisionDx-Melanoma results affect clinical management for early-stage melanoma (CSTL)?

According to the company, results can support risk-aligned decisions such as closer surveillance, sentinel lymph node biopsy consideration, or multidisciplinary referral. The data target patients whose AJCC stage may underestimate recurrence or survival risk.

What cohorts and data sources underpin the DecisionDx-Melanoma findings Castle is presenting (CSTL)?

Castle reports results from a 1,817-patient multi-center cohort and a SEER population-based 5-year outcome study. According to the company, these complementary datasets demonstrate prognostic value across clinical and registry populations.