Abstract 317P
Background
Metastatic breast cancer (MBC) includes tumors of different clinical and biological behavior. Oligometastatic breast cancer (OM) is defined as low volume disease, limited to a maximum of ≤5 lesions, not necessarily in the same organ and potentially susceptible to local treatment. The actual incidence, characteristics, prognosis, and treatment options in OM is a reason for study at the present time.
Methods
Observational, retrospective study of patients with MBC and OM treated in Oncology Department of Morales Meseguer Hospital (Murcia) for the years 2009 to 2020. Overall survival analysis using metods Kaplan Meier and univariate and multivariate Cox models.
Results
In a cohort of 395 patients with MBC, 88 (18.4%) had OM with a median age of 56 years. The clinical-pathological characteristics of OM are detailed in the table. The median overall survival (OS) of OM was 56.7 months (95% CI 42-71) vs 34.9 months (95% CI 28-41) in polymetastatic (p = 0.01). In the univariate analysis, in OM at debut, OS was 69.4 months(95% CI 46-92) vs 48.9 months (95% CI 31-65 CI) in oligorrecurrence (p = 0.05); 1-3 locations,OS was 65.6 months (95% CI 49-81) vs 28.4 months (95% CI 18-38) in 4-5 locations (p = 0.02); in ECOG 0, OS was 74.4 months (95% CI 66-82) vs 48.9 months (95% CI 22-75) in ECOG1 (p = 0.01); the presence of pain was associated with an OS of 41.4 months (95% CI 22-60) vs 83.3 months (95% CI 33-132) in asymptomatic patients (p = 0.01). In the Her2+ phenotype OS was lower than in luminal disease: 54 months (95% CI 23-107) in Her 2+ vs 63 months (95% CI 42-84) in luminal disease (p=0.574). In the multivariate analysis for OS, the ECOG (HR 2.29: 95% CI 1.33-3.95, p= 0.003), number of injuries (HR 2.78: 95% CI 1.19-6.47, p=0.02) and the presence of pain (HR 2.2 95% CI 1.05-4.9, p = 0.03) remained as independent variables. Table: 317P
| Clinical and pathological characteristics | N | % |
| Age (median)56 years (54) | ||
| Hormone-sensitive | 59 | 68.6 |
| Her 2-positive | 11 | 12.8 |
| Triple-negative | 16 | 18.6 |
| Grade 1 | 5 | 5.7 |
| Grade 2 | 43 | 49.4 |
| Grade 3 | 35 | 40.2 |
| Metastasis location (Bone) | 30 | 34.5 |
| Metastasis location (Visceral) | 21 | 24.1 |
| Metastasis location (SNC) | 8 | 9.2 |
| Number of locations (1-3) | 70 | 80.5 |
| Number of locations (4-5) | 17 | 19.5 |
| Oligorecurrence | 63 | 71.6 |
| Oligometastatic | 25 | 28.4 |
| ECOG 0 | 44 | 57.9 |
| ECOG 1 | 28 | 36.8 |
| ECOG 2 | 4 | 5.3 |
| Treatment of the primary tumor (yes) | 83 | 95.4 |
| Treatment of the primary tumor (no) | 4 | 4.6 |
| Type of local treatment (Stereotactic body radiation therapy) | 9 | 18.4 |
| Type of local treatment (Radiotherapy) | 15 | 30.6 |
| Type of local treatment (Surgery) | 25 | 51 |
Conclusions
OM is a subgroup of patients with prolonged survival. The OM at diagnosis, pain and ECOG have been identified in our series as independent prognostic factors of OS.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.