Glaser SL, Clarke CA, Keegan THM, Chang ET, Weisenburger DD. Time Trends in Rates of Hodgkin Lymphoma Histologic Subtypes: True Incidence Changes or Evolving Diagnostic Practice?
Cancer Epidemiol Biomarkers Prev 2015;
24:1474-88. [PMID:
26215294 PMCID:
PMC4592457 DOI:
10.1158/1055-9965.epi-15-0281]
[Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 07/20/2015] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND
Histologic subtypes of classical Hodgkin lymphoma [cHL; e.g., nodular sclerosis, mixed cellularity, not otherwise specified (NOS)] are epidemiologically and prognostically distinctive. Therefore, unexplained, ongoing incidence rate declines for mixed cellularity and increases for NOS require examination.
METHODS
We analyzed detailed histology-specific Hodgkin lymphoma incidence rates in 1992 through 2011 U.S. SEER data (n = 21,372) and reviewed a regional subset of 2007 through 2011 NOS pathology reports for insight into diagnostic practices.
RESULTS
cHL rates were stable until 2007, then decreased for whites [annual percent change (APC) and 95% confidence interval (CI), -3.6% (-5.6% to -1.5%)]. Nodular sclerosis rates declined after 2007 by 5.9% annually, with variation by gender, age, and race/ethnicity. In 1992 through 2011, mixed cellularity rates declined [APC -4.0% (-4.7% to -3.3%)], whereas NOS rates rose [5.3% (4.5%-6.2%)] overall and in most patient groups. The 2007-2011 NOS age-specific rates were more similar to mixed cellularity rates for 1992-1996 than 2007-2011. Trends in combined rates were minimal, supporting increasing misclassification of mixed cellularity, lymphocyte depletion, and specific nodular sclerosis subtypes as NOS. Eighty-eight of 165 reviewed NOS pathology reports addressed classification choice. Twenty (12.1%) justified the classification, 21 (12.7%) described insufficient biopsy material, and coders missed specific subtype information for 27 (16.4%).
CONCLUSION
Recent nodular sclerosis rate declines largely represent true incidence changes. Long-term rate decreases for mixed cellularity and other less common subtypes, and increases for NOS (comprising ∼30% of cHL cases in 2011), likely reflect changes in diagnostic and/or classification practice.
IMPACT
Diminishing histologic subtyping undermines future surveillance and epidemiologic study of Hodgkin lymphoma. Guideline-based use of excisional biopsies and more coding quality control are warranted.
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