Invasive lobular carcinoma of the breast: response to hormonal therapy and outcomes.
Invasive lobular carcinoma (ILC) comprises approximately 5-15% of breast cancers and appears to have a distinct biology. It is less common than invasive ductal carcinoma (IDC) and few large studies have addressed its biologic characteristics and behaviour with respect to long-term clinical outcome and response to adjuvant therapy.


METHODS
This study is based on a large and well-characterised consecutive series of invasive breast carcinomas with a long-term follow-up (up to 25 years). This series included 415 (8%) patients with pure ILC and 2901 (55.7%) with IDC (not otherwise specified) identified from a consecutive cohort of 5680 breast tumours presented to our Breast Unit that were treated in a similar conventional manner. Clinicopathological, therapy and outcome information as well as data on a large panel of biomarkers were available.


RESULTS
Compared to IDC, patients with ILC tended to be older and present with tumours which are more frequently lower grade (typically, grade 2 [84%]), hormone-receptor positive (86% compared to 61% in IDC), of larger size, and with the absence of vascular invasion. A higher frequency of ILC was placed in the good Nottingham Prognostic Index group (40% compared to 21% in IDC). ILC showed indolent but progressive behavioural characteristics with nearly linear survival curves which crossed those of IDC after approximately 10years of follow-up, thus eventually exhibiting a worse long-term outcome. Importantly, ILC showed a better response to adjuvant hormonal therapy (HT) with improvement in survival in patients who received HT compared with matched patients with IDC.


CONCLUSIONS
ILC is a distinct entity of breast cancer that responds well to adjuvant HT. These data add important clinical information for assessing the long-term benefits of adjuvant HT use in ILC.
Department of Histopathology, School of Molecular Medical Sciences, Nottingham University Hospitals NHS Trust, University of Nottingham, Nottingham, UK.
Emad A
EA
Rakha
Maysa E
ME
El-Sayed
Desmond G
DG
Powe
Andrew R
AR
Green
Hany
H
Habashy
Matthew J
MJ
Grainge
John F R
JF
Robertson
Roger
R
Blamey
Julia
J
Gee
Robert I
RI
Nicholson
Andrew H S
AH
Lee
Ian O
IO
Ellis
D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000473:pathology*; D018270:Carcinoma, Ductal, Breast / Q000188:drug therapy / Q000401:mortality / Q000473:pathology*; D018275:Carcinoma, Lobular / Q000188:drug therapy / Q000401:mortality / Q000473:pathology*; D017024:Chemotherapy, Adjuvant; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000188:drug therapy / Q000473:pathology; D009367:Neoplasm Staging; D011379:Prognosis; D016019:Survival Analysis; D016896:Treatment Outcome
D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor