Three Distinct ER-Positive Metastatic Breast Cancer Subgroups as Identified by Agglomerative Hierarchical Cluster Analysis of 18F-FES PET/CT
| Imaging features | Group 1 (n = 26) | Group 2 (n = 27) | Group 3 (n = 38) | P |
| Number of metastases, overall | 3.5 (2.0–10.8) | 33.0 (22.0–55.0) | 5.5 (3.0–10.8) | 7.45E−11 |
| Number of metastases, bone | 2.0 (0.0–7.8) | 26.0 (19.0–47.5) | 2.0 (1.0–5.0) | 1.35E−11 |
| Geometric mean 18F-FES SUVmax | 1.1 (1.0–1.4) | 3.4 (2.5–4.7) | 2.7 (2.3–3.6) | 7.29E−12 |
| Percentage metastases visible on CT per patient | 100.0 (94.6–100.0) | 40.0 (28.2–59.5) | 55.0 (31.8–96.9) | 9.96E−09 |
| Percentage metastases positive on 18F-FES PET | 3.6 (0.0–31.2) | 100.0 (90.9–100.0) | 100.0 (91.0–100.0) | 6.27E−14 |
| Number of metastases visible on CT | 3.0 (2.0–10.0) | 14.0 (5.5–24.5) | 2.5 (1.0–5.0) | 9.36E−07 |
| Number of metastases positive on 18F-FES PET | 0.5 (0.0–1.0) | 28.0 (20.0–54.5) | 5.5 (2.2–9.0) | 6.99E−14 |
Imaging features were first assessed on a patient level and then summarized per group as medians, with interquartile ranges in parentheses; P values are based on Kruskal–Wallis rank sum tests.