The role of histological subtype in hormone receptor positive metastatic breast cancer: similar survival but different therapeutic approaches.
BACKGROUND
This study describes the differences between the two largest histological breast cancer subtypes (invasive ductal carcinoma (IDC) and invasive (mixed) lobular carcinoma (ILC) with respect to patient and tumor characteristics, treatment-choices and outcome in metastatic breast cancer.


RESULTS
Patients with ILC were older at diagnosis of primary breast cancer and had more often initial bone metastasis (46.5% versus 34.8%, P = 0.01) and less often multiple metastatic sites compared to IDC (23.7% versus 30.9%, P = 0.11). Six months after diagnosis of metastatic breast cancer, 28.1% of patients with ILC and 39.8% of patients with IDC had received chemotherapy with a longer median time to first chemotherapy for those with ILC (P = 0.001). After six months 84.8% of patients with ILC had received endocrine therapy versus 72.5% of patients with IDC (P = 0.0001). Median overall survival was 29 months for ILC and 25 months for IDC (P = 0.53).


METHODS
We included 437 patients with hormone receptor-positive IDC and 131 patients with hormone receptor-positive ILC, all diagnosed with metastatic breast cancer between 2007-2009, irrespective of date of the primary diagnosis. Patient and tumor characteristics and data on treatment and outcome were collected. Survival curves were obtained using the Kaplan-Meier method.


CONCLUSIONS
Treatment strategies of hormone receptor-positive metastatic breast cancer were remarkably different for patients with ILC and IDC. Further research is required to understand tumor behavior and treatment-choices in real-life.
GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.|Department of Internal Medicine, Máxima Medical Center, Veldhoven, The Netherlands.
Dorien
D
Lobbezoo
GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.|Department of Surgery, Máxima Medical Center, Veldhoven, The Netherlands.
Wilfred
W
Truin
GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.
Adri
A
Voogd
GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.|Department of Surgery, Máxima Medical Center, Veldhoven, The Netherlands.
Rudi
R
Roumen
GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.|Department of Internal Medicine, Máxima Medical Center, Veldhoven, The Netherlands.
Gerard
G
Vreugdenhil
Department of Internal Medicine, Máxima Medical Center, Veldhoven, The Netherlands.
Marcus Wouter
MW
Dercksen
Department of Internal Medicine, Atrium-Orbis, Heerlen, The Netherlands.
Franchette
F
van den Berkmortel
Department of Internal Medicine, Jeroen Bosch Hospital, Den Bosch, The Netherlands.
Tineke
T
Smilde
Department of Internal Medicine, VieCuri Medical Center, Venlo, The Netherlands.
Agnes
A
van de Wouw
GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.|Department of Internal Medicine, Atrium-Orbis, Sittard, The Netherlands.
Roel
R
van Kampen
Department of Internal Medicine, St Elisabeth Hospital, Tilburg, The Netherlands.
Johanna
J
van Riel
Department of Internal Medicine, St Jans Hospital, Weert, The Netherlands.
Natascha
N
Peters
Department for Health Evidence, Radboud University Medical Center, Nijmegen, The Netherlands.
Petronella
P
Peer
GROW, School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands.
Vivianne C G
VC
Tjan-Heijnen
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000401:mortality; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy* / Q000401:mortality; D018275:Carcinoma, Lobular / Q000188:drug therapy* / Q000401:mortality; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone
histology; invasive ductal carcinoma; invasive lobular carcinoma; metastatic breast cancer; treatment