ECOG Performance Status and Other Prognostic Factors in Mesothelioma: What the Numbers Mean for Your Options

When an oncology team talks about prognosis in pleural mesothelioma, they are rarely working from stage alone. They weigh a small set of clinical numbers shown across decades of trials to predict how the disease behaves and how well a person will tolerate treatment. The most important of those numbers is performance status. This guide is for someone who keeps hearing “ECOG 1” and wants to understand what is being measured and why it shapes the treatment options on the table.

What ECOG Performance Status Is

The Eastern Cooperative Oncology Group performance status scale was published by Martin Oken and colleagues in 1982 as part of a broader set of toxicity and response criteria for cancer trials (American Journal of Clinical Oncology 1982;5(6):649-655). It runs from 0 to 5, and the definitions have not substantively changed since the original publication.

The grade is assigned by the clinician based on history and observation, not a self-reported survey. Two clinicians can disagree by one grade, particularly between ECOG 1 and ECOG 2, and that boundary is where most trial-eligibility questions sit. The older Karnofsky Performance Status scale (Karnofsky and Burchenal, 1949) runs from 100 to 0 in 10-point increments and is used interchangeably: KPS 100 corresponds to ECOG 0, KPS 80 to ECOG 1, KPS 60 to ECOG 2, KPS 40 to ECOG 3. Modern mesothelioma trials predominantly specify ECOG.

Why Performance Status Drives Treatment Options

Stage describes the anatomy of the disease. Performance status describes how the person is functioning in daily life with that disease. For treatment selection, performance status often drives the decision more than stage does, because the trials that defined modern first-line care almost universally enrolled only ECOG 0 or 1 patients.

CheckMate-743 (nivolumab plus ipilimumab) and IND.227 / KEYNOTE-483 (pembrolizumab plus pemetrexed and platinum chemotherapy) both required ECOG 0 or 1 at enrollment. The CONFIRM trial of nivolumab in the second-line setting was similarly restricted. The headline median overall survival numbers from those trials, 18.1 and 17.3 months in the immunotherapy arms, describe outcomes in fit patients who could be safely enrolled. They do not describe what happens for someone presenting with ECOG 2 or 3.

This creates a real evidence gap. There is no phase 3 randomized data for first-line immunotherapy in ECOG 2 or worse mesothelioma, and the decision in that setting becomes a careful conversation about tolerability against the risk of treatment-related decline. For clinical trial enrollment, the same constraint applies: most active phase 2 and phase 3 mesothelioma trials specify ECOG 0 or 1.

CALGB Prognostic Groups: The Edwards Model

The first widely adopted prognostic model in pleural mesothelioma came from the Cancer and Leukemia Group B (CALGB), originally published by Herndon and colleagues in Chest in 1998 and refined by Edwards and colleagues in Thorax in 2000. The Edwards analysis identified five independent poor prognostic factors: poor performance status (ECOG ≥1), non-epithelioid histology, male sex, low hemoglobin, and a high white blood cell count (8.3 × 10⁹/L or above).

Patients were stratified by the number of poor factors. The original Herndon CALGB analysis used regression-tree methodology to define six prognostic subgroups, with median survival ranging from 13.9 months in the best group down to 1.4 months in the worst. The model predates pemetrexed chemotherapy, bevacizumab, and checkpoint inhibitors, but the factors it identified have held up. Performance status, histology, hemoglobin, and white blood cell count still appear in every modern model.

EORTC Prognostic Score: The Curran Model

The European Organisation for Research and Treatment of Cancer (EORTC) prognostic score, published by Curran and colleagues in the Journal of Clinical Oncology in 1998, was developed in 204 patients accrued across five consecutive EORTC phase II chemotherapy trials between 1984 and 1993.

The multivariate model assigns weighted points to five factors: poor WHO performance status, a high white blood cell count, sarcomatoid histology, male sex, and a probable or possible (rather than definite) histologic diagnosis. Patients are divided into a good-prognosis group and a poor-prognosis group, with one-year survival of roughly 40% versus 12%. The EORTC and CALGB scores identify largely overlapping factors and were both built in the pre-pemetrexed era, but the underlying factor selection has held up in modern series.

Modern Prognostic Models: The Brims Decision Tree

The most-cited contemporary prognostic model is the decision-tree analysis published by Fraser Brims and colleagues in the Journal of Thoracic Oncology in 2016. Working from a 482-patient derivation cohort with an independent 174-patient external validation cohort, the group used classification and regression tree methodology to identify four variables: hemoglobin, serum albumin, ECOG performance status, and weight loss.

The model produced risk groups with median overall survival ranging from 34.0 months in the best group to 7.5 months in the worst. Histology shifted outcomes within groups. The C-statistic was 0.761 in the derivation cohort and 0.68 in external validation, which is good discrimination for a model that requires only a complete blood count, a basic metabolic panel, and a brief history. The cohort predates routine first-line immunotherapy, so absolute survival in each group is likely longer for patients on modern regimens, but a 2022 validation by Cedrés and colleagues in Lung Cancer confirmed the model’s discrimination in the bevacizumab era.

How Performance Status Interacts With Histology and Stage

Each prognostic axis carries information the others miss. A patient at ECOG 1 with epithelioid stage I disease and a normal hemoglobin sits in the low-risk Brims group and is a candidate for the most aggressive multimodal options. A patient at ECOG 1 with sarcomatoid stage III disease and a hemoglobin of 11 sits in a high-intermediate or high-risk group despite the same performance status, and the conversation shifts toward systemic therapy with realistic durability expectations.

For survival data stratified by stage and histology, the picture sharpens further. CheckMate-743 reported a median overall survival of 18.8 months on nivolumab plus ipilimumab in non-epithelioid histology versus 8.8 months on chemotherapy, while the epithelioid difference was modest. Performance status is also central to second-line decisions after progression: the CONFIRM trial of nivolumab in previously treated mesothelioma, the strongest randomized evidence in that setting, enrolled ECOG 0 or 1 patients only. Oncology teams document performance status at every visit because a trend matters more than a single reading.

For broader context on how these numbers come together in newly diagnosed disease, see our first-line treatment decision guide and the treatment landscape overview. Reviewer Dr. Hedy Kindler directs the Multidisciplinary Mesothelioma Program at the University of Chicago.