Primary and secondary distant metastatic breast cancer: two sides of the same coin.
OBJECTIVE
This study evaluated the differences between breast cancer (BC) patients who present with primary distant metastatic disease (PMD) and those who develop distant metastases during the course of their illness (secondary metastatic disease [SMD]) with regard to clinicopathological characteristics, patterns of metastatic sites, palliative therapy and survival.


METHODS
Based on a cohort of patients with newly diagnosed BC (n = 1459), we analyzed all patients who had PMD (n = 92, 6.3%) and those who developed SMD (n = 277, 20.3%).


RESULTS
There were no significant differences with regard to the patient's age in which metastatic disease had been diagnosed (PMD/SMD: 64 years/66 years, p = 0.19). The SMD group had more often triple-negative carcinomas (25.5%/7.3%, p = 0.019); there were no significant differences with regard to grading (p = 0.61), HER2 status (p = 0.67) and hormonal receptor status (p = 1.00). The mean number of metastatic locations was similar (2.3/2.3, p = 0.91). While patients with PMD usually initiated systemic therapy, patients with SMD received systemic therapy after diagnosis of metastatic disease less often (16.4%/2.6%, p < 0.001). Both groups received palliative chemotherapy similarly often (PMD/SMD: 62.8%/63.3%, p = 1.00). The mean number of palliative therapy lines was similar (PMD/SMD: 2.8/3.2, p = 0.39). Compared to patients with SMD, patients who had PMD had a significantly improved metastatic disease survival (p < 0.001). The one-year, two-year and five-year survival rates were as follows: 76.9%/60.3%, 58.2%/43.0%, 23.1%/10.6%. The median survival times were 18.5 months and 32 months.


CONCLUSIONS
The poorer prognosis of patients with SMD may be explained by differences in clinicopathological features of the tumor, metastatic patterns, the use palliative therapy and drug resistance of the tumor cells which occurs in therapy-naïve PMD patients at a later phase of the disease course.
University Hospital Basel (UHB), Department of Gynecology and Obstetrics, Spitalstrasse 21, CH-4031 Basel, Switzerland; Cantonal Hospital Winterthur, Department of Gynecology and Obstetrics, Brauerstrasse 15, CH-8401 Winterthur, Switzerland; Breast Center "SenoSuisse", Brauerstrasse 15, CH-8401 Winterthur, Switzerland. Electronic address: uwe.gueth@unibas.ch.
Uwe
U
Güth
University Hospital Basel (UHB), Department of Gynecology and Obstetrics, Spitalstrasse 21, CH-4031 Basel, Switzerland.
Isotta
I
Magaton
University Hospital Basel (UHB), Department of Gynecology and Obstetrics, Spitalstrasse 21, CH-4031 Basel, Switzerland.
Dorothy Jane
DJ
Huang
The Royal Marsden NHS Foundation Trust, Fulham Road, London SW36 JJ, United Kingdom.
Rosalie
R
Fisher
Eudox Institute for Biomathematics, Malzgasse 9, CH-4052 Basel, Switzerland.
Andreas
A
Schötzau
UHB, Department of Oncology, Petersgraben 4, CH-4031 Basel, Switzerland.
Marcus
M
Vetter
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000378:metabolism / Q000556:secondary* / Q000628:therapy; D001932:Brain Neoplasms / Q000378:metabolism / Q000556:secondary* / Q000628:therapy; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000628:therapy; D018270:Carcinoma, Ductal, Breast / Q000378:metabolism / Q000556:secondary* / Q000628:therapy; D018275:Carcinoma, Lobular / Q000378:metabolism / Q000556:secondary* / Q000628:therapy; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000556:secondary* / Q000628:therapy; D008175:Lung Neoplasms / Q000378:metabolism / Q000556:secondary* / Q000628:therapy; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008875:Middle Aged; D010166:Palliative Care; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D016896:Treatment Outcome; D064726:Triple Negative Breast Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000628:therapy
D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human
Breast cancer; Primary metastatic disease; Prognosis; Secondary metastatic disease; palliative therapy