Metastatic behavior of breast cancer subtypes.
OBJECTIVE
Prognostic and predictive factors are well established in early-stage breast cancer, but less is known about which metastatic sites will be affected.


METHODS
Patients with early-stage breast cancer diagnosed between 1986 and 1992 with archival tissue were included. Subtypes were defined as luminal A, luminal B, luminal/human epidermal growth factor receptor 2 (HER2), HER2 enriched, basal-like, and triple negative (TN) nonbasal. Distant sites were classified as brain, liver, lung, bone, distant nodal, pleural/peritoneal, and other. Cumulative incidence curves were estimated for each site according to competing risks methods. Association between the site of relapse and subtype was assessed in multivariate models using logistic regression.


RESULTS
Median follow-up time among 3,726 eligible patients was 14.8 years. Median durations of survival with distant metastasis were 2.2 (luminal A), 1.6 (luminal B), 1.3 (luminal/HER2), 0.7 (HER2 enriched), and 0.5 years (basal-like; P < .001). Bone was the most common metastatic site in all subtypes except basal-like tumors. In multivariate analysis, compared with luminal A tumors, luminal/HER2 and HER2-enriched tumors were associated with a significantly higher rate of brain, liver, and lung metastases. Basal-like tumors had a higher rate of brain, lung, and distant nodal metastases but a significantly lower rate of liver and bone metastases. TN nonbasal tumors demonstrated a similar pattern but were not associated with fewer liver metastases.


CONCLUSIONS
Breast cancer subtypes are associated with distinct patterns of metastatic spread with notable differences in survival after relapse.
Kennecke
Hagen
H
Vancouver Clinic, Division of Medical Oncology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada. hkennecke@bccancer.bc.ca
Yerushalmi
Rinat
R
Woods
Ryan
R
Cheang
Maggie Chon U
MC
Voduc
David
D
Speers
Caroline H
CH
Nielsen
Torsten O
TO
Gelmon
Karen
K
D000368:Aged; D001859:Bone Neoplasms / Q000453:epidemiology / Q000556:secondary; D001943:Breast Neoplasms / Q000378:metabolism / Q000401:mortality* / Q000473:pathology*; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D046888:Tissue Array Analysis
D066246:ErbB Receptors