Tumour location within the breast: Does tumour site have prognostic ability?
BACKGROUND
Tumour location within the breast varies with the highest frequency in the upper outer quadrant (UOQ) and lowest frequency in the lower inner quadrant (LIQ). Whether tumour location is prognostic is unclear. To determine whether tumour location is prognostic, associations between tumour site and clinicopathological characteristics were evaluated.


METHODS
All patients enrolled in the Clinical Breast Care Project whose tumour site-UOQ, upper inner quadrant (UIQ), central, LIQ, lower outer quadrant (LOQ)-was determined by a single, dedicated breast pathologist were included in this study. Patients with multicentric disease (n = 122) or tumours spanning multiple quadrants (n = 381) were excluded from further analysis. Clinicopathological characteristics were analysed using chi-square tests for univariate analysis with multivariate analysis performed using principal components analysis (PCA) and multiple logistic regression. Significance was defined as P < 0.05.


RESULTS
Of the 980 patients with defined tumour location, 30 had bilateral disease. Tumour location in the UOQ (51.5%) was significantly higher than in the UIQ (15.6%), LOQ (14.2%), central (10.6%), or LIQ (8.1%). Tumours in the central quadrant were significantly more likely to have higher tumour stage (P = 0.003) and size (P < 0.001), metastatic lymph nodes (P < 0.001), and mortality (P = 0.011). After multivariate analysis, only tumour size and lymph node status remained significantly associated with survival.


CONCLUSIONS
Evaluation of tumour location as a prognostic factor revealed that although tumours in the central region are associated with less favourable outcome, these associations are not independent of location but rather driven by larger tumour size. Tumours in the central region are more difficult to detect mammographically, resulting in larger tumour size at diagnosis and thus less favourable prognosis. Together, these data demonstrate that tumour location is not an independent prognostic factor.
Clinical Breast Care Project, Windber Research Institute, Windber, Pennsylvania 15963, USA.
Seth
S
Rummel
Clinical Breast Care Project, Murtha Cancer Centre, Walter Reed National Military Medical Centre, Bethesda, Maryland 20889, USA.
Matthew T
MT
Hueman
Clinical Breast Care Project, Windber Research Institute, Windber, Pennsylvania 15963, USA.
Nick
N
Costantino
Clinical Breast Care Project, Murtha Cancer Centre, Walter Reed National Military Medical Centre, Bethesda, Maryland 20889, USA.
Craig D
CD
Shriver
Clinical Breast Care Project, Murtha Cancer Centre, Walter Reed National Military Medical Centre, Bethesda, Maryland 20889, USA.
Rachel E
RE
Ellsworth
breast quadrants; prognosis; tumour location