Table 3.

Summary of the prognosis prediction models created by machine learning.

Model	Development	Variables to Input	Patient Population	Prediction of Survival	External Validation
PathFx model 1.0	Forsberg et al. [20], 2011	Not available	189 patients treated for metastatic bone disease between 1999 and 2003	Survival at 1, 3, 6, 12, 18, and 24 months	Forsberg et al. [10], 2012; Piccioli et al. [9], 2015; Forsberg et al. [12], 2017; Ogura et al. [11], 2017; Meares et al. [14], 2019
PathFx model 2.0	Overmann et al. [21], 2020	Not available	189 patients treated for metastatic bone disease between 1999 and 2003	Survival at 1, 3, 6, 12, 18, and 24 months	Overmann et al. [21], 2020
PathFx model 3.0 (https://www.pathfx.org)	Anderson et al. [13], 2020	Age, sex, oncologic diagnosis, pathological fracture, ECOG performance status, hemoglobin level, absolute lymphocyte count, number of skeletal metastases, organ metastases. In case of prostate cancer, PSA, patient age at metastases, treatment, race, comorbidity, alkaline phosphatase velocity.	208 patients treated for metastatic bone disease between 2015 and 2018	Survival at 1, 3, 6, 12, 18, and 24 months	Anderson et al. [13], 2020
Machine Learning Algorithm (https://sorg-apps.shinyapps.io/extremitymetssurvival/)	Thio et al. [19], 2020	Age, primary tumor type, visceral metastases, brain metastases, previous systemic therapy, hemoglobin level, white blood cell count, platelet count, absolute lymphocyte count, absolute neutrophil count, albumin level, alkaline phosphatase level, calcium, creatinine, sodium.	1090 patients treated surgically for long bone metastases between 1999 and 2017	Survival at 3 and 12 months	None
SORG Machine Learning Algorithm (https://sorg-apps.shinyapps.io/spinemets/, accessed on 10 July 2021)	Karhade et al. [22], 2018	White blood cell, albumin, American Society of Anesthesiologist Class, spine location, functional status, hematocrit, alkaline phosphatase.	1790 patients treated surgically for spinal metastatic disease between 2000 and 2016	Survival at 1 month	None
Machine Learning Algorithm (https://sorg-apps.shinyapps.io/spinemetssurvival/, accessed on 10 July 2021)	Karhade et al. [23], 2019	BMI, other Charlson comorbidity, primary tumor histology, ECOG performance status, ASIA, number of spine metastases, visceral metastases, brain metastases, previous systemic therapy, hemoglobin, platelet, absolute lymphocyte, albumin, alkaline phosphatase, creatinine, INR.	732 patients treated surgically for spinal metastatic disease between 2000 and 2016	Survival at 3 and 12 months	None

ECOG, Eastern Cooperative Oncology Group; PSA, Prostate Specific Antigen; BMI, Body Mass Index; ASIA, American Spinal Injury Association; INR, international normalized ratio.