Characteristics of the study population
| Characteristics | Total (n=1,122) | PET (n=242) | Surgery (n=880) | P |
| Age (years) | <0.0001 | |||
| ≥70-74 | 22 (5.5%) | 381 (94.5%) | ||
| ≥75-79 | 52 (16.1%) | 271 (83.9%) | ||
| ≥80-84 | 65 (30.8%) | 146 (69.2%) | ||
| ≥85-90 | 62 (48.4%) | 66 (51.6%) | ||
| ≥>90 | 41 (71.9%) | 16 (28.1%) | ||
| Median (range) | 84 (70-101) | 76 (70-94) | ||
| Tumour grade | 0.953 | |||
| ≥1 | 46 (21.7%) | 166 (78.3%) | ||
| ≥2 | 144 (22.0%) | 510 (88.0%) | ||
| ≥3 | 31 (19.4%) | 129 (80.6%) | ||
| Missing | 21 (21.9%) | 75 (78.1%) | ||
| HER2 status | 0.0042 | |||
| Positive/borderline | 17 (12.5%) | 119 (87.5%) | ||
| Negative | 158 (20.9%) | 597 (79.1%) | ||
| Missing | 67 (29.0%) | 164 (71.0%) | ||
| Nodal status | 0.0194 | |||
| Positive | 51 (28.3%) | 129 (71.7%) | ||
| Negative | 183 (20.0%) | 734 (80.0%) | ||
| Missing | 8 (32.0%) | 17 (68.0%) | ||
| Tumour size | <0.0001 | |||
| ≥<10 mm | 15 (12.6%) | 104 (87.4%) | ||
| ≥10-19.9 mm | 64 (17.0%) | 312 (83.0%) | ||
| ≥20-49.9 mm | 126 (24.2%) | 395 (75.8%) | ||
| ≥≥50 mm | 29 (38.7%) | 46 (61.3%) | ||
| Missing | 8 (25.8%) | 23 (74.2%) | ||
| Median size (range) (mm) | ||||
| Mini-Mental State Examination (MMSE) score | <0.0001 | |||
| ≥27-30 | 114 (16.7%) | 569 (83.3%) | ||
| ≥22-26 | 37 (27.8%) | 96 (72.2%) | ||
| ≥0-21 | 19 (44.2%) | 24 (55.8%) | ||
| Missing | 72 (27.4%) | 191 (72.6%) | ||
| Median MMSE score (range) | ||||
| Activities of daily living (ADL) score | <0.0001 | |||
| Fully independent | 128 (15.1%) | 720 (84.9%) | ||
| Dependent in 1 or more category | 72 (47.4%) | 80 (52.6%) | ||
| Missing | 42 (34.4%) | 80 (65.6%) | ||
| Charlson Comorbidity Index (CCI) score | <0.0001 | |||
| ≥0 | 71 (13.3%) | 462 (86.7%) | ||
| ≥1 | 52 (26.1%) | 147 (73.9%) | ||
| ≥2 | 47 (24.0%) | 149 (76.0%) | ||
| ≥≥3 | 58 (38.7%) | 92 (61.3%) | ||
| Missing | 14 (31.8%) | 30 (68.2%) | ||
| Median CCI score (range) | <0.0001 | |||