<p><span>The Ghartey Scalar (Gs): Combining Structural Burden with Biological Activity for Breast Cancer Prognosis -A Proof-of-Concept Evaluation Against the Nottingham Prognostic Index in Two Independent Cohorts</span></p>
Frank Naku Ghartey
Source abstract
Background Established breast cancer prognostic tools need inputs that are often unreliable where most of the disease burden falls. The Ghartey Scalar (Gs) represents disease as accumulated structural burden modified by biological activity. This paper evaluates its current formulation, the augmented scalar (AugGs). Methods AugGs is 25(4 + c) / (√Mtotal × (V + c)), with Mtotal adding tumour, nodal and metastatic burden and V a normalised activity term. The specification requires V from serial markers and defines a trajectory term; neither cohort supported these, so histological grade served as a static proxy, incremented by one for triple-negative and HER2-positive tumours. This is a test of burden and static activity, not of velocity. Discrimination was measured by Harrell's cstatistic with bootstrap confidence intervals in METABRIC (1,352 patients, 458 breast cancer deaths) and in the population-based SCAN-B series (3,114 patients, 2,706 with receptor status). AugGs has no fitted parameters, so the second cohort is an external test. Results In METABRIC, AugGs reached 0.699 against 0.685 for the Nottingham Prognostic Index (NPI) on breast cancer death (+0.015, 95% CI +0.004 to +0.026) and 0.657 against 0.645 on all-cause mortality (+0.013, +0.004 to +0.021). In SCAN-B it reached 0.654 against 0.637 (+0.016, +0.005 to +0.027). The activity term added +0.021 (+0.005 to +0.036) over burden alone in METABRIC and +0.015 (+0.003 to +0.028) in SCAN-B. The subtype increment gained +0.010 (+0.003 to +0.017) in METABRIC and was null in SCAN-B, its HER2 component reversing sign between the two treatment eras. Conclusions A scalar combining structural burden with a static measure of biological activity exceeded an established index in two independent cohorts, needing no axillary node count and no tuned configuration. This is a proof of concept in screen-detected, early-stage populations. Performance in the late-presenting populations the framework targets is not established, and that evaluation is the next step.
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