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 CC4K (Cancer Classifications for Kids) provides a harmonized, computable pediatric cancer classification framework used across [St. Jude Cloud](https://stjude.cloud) and by the [CCDI Federated API](https://github.com/CBIIT/ccdi-federation-api).
 
+## v0.5.3
+
+Submitted: October 1, 2026
+
+Click [here](/files/cc4k/Official_CC4K_v0.5.3.xlsx){target="_blank"} to download.
+
+Version 0.5.3 extends the CC4K hematologic malignancy hierarchy while advancing the review and harmonization of sample classifications across CC4K and related St. Jude resources.
+This release adds five new disease classifications, identified through newly curated cases and aligned with the WHO Classification of Haematolymphoid Tumors, 5th edition (WHO5): Mixed Phenotype Acute Leukemia with KMT2A Rearrangement, Extranodal NK/T-cell Lymphoma, Anaplastic Large Cell Lymphoma, ALK Negative, Diffuse Large B-cell Lymphoma, EBV Positive, and Pediatric-type Follicular Lymphoma.
+These additions address classification gaps identified during case review and maintain alignment with current hematolymphoid classification standards.
+This focused update reflects the continued refinement of CC4K through new case curation, and classification review.
+No broad structural reorganization of the classification tree was performed in this release.
+
 ## v0.5.2
 
 Submitted: June 30, 2026
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