Pattern of metastatic spread in triple-negative breast cancer.
OBJECTIVE
The prognosis of women with triple-negative breast cancers (defined as cancers that are estrogen receptor-negative, progesterone receptor-negative and HER2/neu negative) is poor, compared to women with other subtypes of breast cancer. It is proposed that the underlying difference in recurrence rates may be explained in part by different routes of metastatic spread.


METHODS
We studied a cohort of 1608 patients diagnosed with breast cancer, diagnosed between January 1987 and December 1997 at Women's College Hospital in Toronto. Triple-negative breast cancers were defined as those that were estrogen receptor-negative, progesterone receptor-negative and HER2/neu-negative. We compared the incidence rates of metastatic spread to bone and to other (non-bone) organs in women with triple-negative and other forms of breast cancer.


RESULTS
Of the 1,608 patients, 180 (11.2%) had triple-negative breast cancer. The 1608 women were followed for a median of 9.0 years (range 0.1-19 years). Compared to other patients, those with triple-negative breast cancer had an increased likelihood of distant recurrence over the study period (adjusted hazard ratio (HR) 1.9; 95% CI: 1.5-2.5, P < 0.0001). The relatively poor prognosis was apparent in the five years after diagnosis (HR 2.9; 95% CI: 2.1-3.9; P = 0.0001) but not thereafter (HR 0.5; 95% CI: 0.2-1.1; P = 0.07). In particular, women with triple-negative breast cancer were four times more likely to experience a visceral metastasis within five years of diagnosis than those with other types of cancer (HR 4.0; 95% CI: 2.7-5.9; P < 0.0001). The rates of bone metastases were comparable for triple-negative and for other forms of cancer in this time period (HR 0.8; 95% CI: 0.4-1.6 P = 0.5).


CONCLUSIONS
The excess risk of distant recurrence in triple-negative breast cancers, versus other forms of cancer, is attributable in large part to an excess of visceral metastases in the first five years following diagnosis.
Department of Medical Oncology, Sunnybrook Health Sciences Center, University of Toronto, Toronto, ON, Canada.
Rebecca
R
Dent
Wedad M
WM
Hanna
Maureen
M
Trudeau
Ellen
E
Rawlinson
Ping
P
Sun
Steven A
SA
Narod
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001859:Bone Neoplasms / Q000453:epidemiology / Q000556:secondary; D001943:Breast Neoplasms / Q000378:metabolism / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000473:pathology*; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D014781:Viscera / Q000473:pathology
D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone