"Lumping" vs "splitting" in oncologic pathology: association with cancer center type and case volume.

Context: Prior studies reported associations of cancer center facility type and case volume with cancer outcomes (such as survival) and treatment-related processes (such as treatment with chemotherapy, surgery, or radiotherapy).
Objective: To determine whether facility characteristics are associated with use of broad (lumped) vs narrow (split) diagnoses in cancer pathology.
Design: We examined associations of facility characteristics and prevalence of broad diagnoses that might adversely affect treatment decisions (based on National Comprehensive Cancer Network treatment guidelines) in National Cancer Data Base records for patients diagnosed from 2004-2008. Logistic regression was used to determine whether associations of facility type and volume with prevalence of broad diagnoses were independent of patient demographic/socioeconomic factors.
Results: Among 10 high incidence cancer sites, 5 had a prevalence of broad diagnoses exceeding 6%. For 4 of these, use of broad diagnoses was independently lower in NCI (National Cancer Institute)- designated comprehensive programs than in community programs, with multivariate prevalence ratios (PR) as low as 0.46 (95% confidence interval [CI] 0.35-0.59) for uterine corpus cancers and 0.49 (95% CI 0.44-0.55) for kidney and renal pelvis cancers. Differences between low- and high-volume facilities were observed for 4 of the 5 sites, with multivariate PR as low as 0.67 (95% CI 0.59-0.77) and 0.72 (95% CI 0.63-0.82) for cancers of the uterine corpus and lung, respectively.
Conclusion: Prevalence of broad cancer diagnoses varies independently by cancer site/type, facility type, and facility volume. Broader diagnoses tend to be used most often by community cancer centers and low-volume centers. This association has implications for use of registry data in pathology quality assessment and quality improvement.