Multivariate Analysis of Breast Cancer-Specific Mortality (BCSM).

Abbreviations: HR = hazard ratio; CI = confidence interval; AJCC = American Joint Committee on Cancer; LN = lymph node; ER = estrogen receptor; PR = progesterone receptor; RT = radiotherapy; UO = upper outer quadrant of breast; UI = upper inner quadrant of breast; LI = lower inner quadrant of breast; LO = lower outer quadrant of breast; CEN = central portion quadrant of breast.*Pairwise comparisons were conducted to clarify the difference on HR at different primary site. P1 value, using UO as the reference, indicated best prognosis for patients with tumors at UO. From another point of view, P2 value, using CEN as the reference, indicated that patients with tumors at CEN and LO had worse prognosis than those at UO, but better prognosis than those at UI and LI.