Patient and disease characteristics
After excluding files with essential missing data, 631 cases referred for surgery in our institution were chosen for the final analysis. In the general breast cancer patient population (Table 1), the average age was 53.7 years, ranging between 24 and 81 years. Further, 79.4% (501) were postmenopausal, and a family history of cancer was recorded in 15.7% (99). The main concern was the external quadrant in 58.9% of cases (372) and those more likely to have stage II of the disease (500; 79.24%). Radical surgery was the initial treatment in 448 patients (71%), and all were exposed to adjuvant chemotherapy and irradiation. Most participants (518; 82.1%) had invasive ductal carcinoma histology, 85 (13.5%) displayed characteristics of the TNBC phenotype, 228 (36.13%) bore a luminal A subtype, 261 (41.36%) bore a luminal B subtype, and 57 (9.03%) had HER2 overexpressing tumors, of which 26 (4.12%) were hormonal receptor negative (Table 1).
(To view a larger version of Table 1, click here.)
Regarding the histopathological and IHC characteristics, the primary tumor (pT) stage was primarily pT1b–pT2 in 569 patients (90.2%), the tumor grade was II for 346 patients (54.83%), lymph node involvement was recorded in 264 patients (41.64%), and lymphovascular invasion was seen in 550 patients (87.16%). The average expression of ER was 38.6% (range, 0%–80%), and for PR it was 31.3% (range, 0%–95%), with more than half of the cases displaying a score >10% (67.8%, 429 patients and 60.7%, 383 patients, respectively). The mean score of Ki67 was 25.2% (range, 1%–80%) in 5.7% being superior to 60%. The expression of HER2, as determined by IHC, was positive or equivocal in 118 patients (18.7%).
The average age in the TNBC population was 52.3 years, of which 28.2% (24 patients) were premenopausal, 7% (six patients) had a recorded family history of cancer, and 88.2% (75 patients) were stage II, whereas the external and internal mammary quadrants were proportionally involved. Radical mastectomy was the surgical approach in 60% of cases (51 patients) (Table 1). The histopathology in cases other than invasive ductal carcinoma was medullary carcinoma (4.7%, four patients) and metaplastic carcinoma (1.2%, one patient). Tumor grade III was predominant (63 patients, 74.1%), tumor stage pT2 was noted in 51 patients (60%), nodal involvement was recorded in 34.1% (29 patients), and lymphovascular invasion was identified in four cases (4.7%). HER2 was expressed in 10 cases (11.8%), while Ki67 expression ranged between 5% and 80%, with an average of 44.7%. More than half (58.8%) of the patients had a Ki67 value between 21% and 60%, and 23.5% had a value >60%. All patients underwent adjuvant chemotherapy, which contained anthracycline in 44 cases (51.8%).
Biomarker expression and correlations
In the general population, EGFR expression was significantly directly correlated with tumor grade (P=0.002), lymph node involvement (P=0.006), capsular effraction (P=0.011), and hormone receptor expression (P=0.004), and E-cad was significantly directly correlated with tumor stage (P=0.03), and Ki67 (P=0.003) and PR (P=0.007) expression. CK5/6 positivity was significantly correlated with the clinical stage (P=0.0039) and the presence of an in situ component (P=0.027). The positivity of p53 was significantly correlated with quadrant involvement (internal vs external; P=0.028), pT (P=0.028), the multifocal character of the tumor (P=0.028), and the IHC surrogate phenotype (P<0.0001). Positive Bcl2 staining was directly correlated with the Ki67 score (P=0.006) and phenotype (P=0.002), whereas Cox-2 was directly correlated with the clinical stage (P<0.0001) and pT (P=0.0025). Significant direct correlations with the phenotype were also found for the remaining three biomarkers (p53, P<0.0001; Bcl2, P=0.002; Cox-2, P=0.004), whereas TOP2A was significantly directly correlated with HER2 expression (P=0.003).
The frequency of biomarker expression in relapsed vs non-relapsed breast cancer patients significantly correlated with cancer recurrence as follows: for Ki67 <20%, 42.5% vs 54.1%; for Ki67 20%–60%, 52.8% vs 40%; and for Ki67 >60%, 4.7% vs 5.9%. Similarly, for CK5/6 negative, the proportions were 55.9% (19) vs 36.8% (53) and for CK5/6 positive, they were 44.1% (15) vs 63.2% (91). Direct correlations were found between CK5/6 and E-cad (P<0.0001) and between CK5/6 and Cox-2 (P=0.037).
In the specific TNBC population, significant or marginal correlations were revealed for CK5/6 (P=0.010) and E-cad (P=0.0016) with clinical stage, for EGFR with histopathological type (P=0.041), for p53 with the principally involved quadrant (external vs internal; P=0.02), for Bcl2 with menopausal status (P=0.004) and BMI (P=0.015), and for TOP2A with the in situ component (P=0.013). Cox-2 positivity was marginally inversely correlated with capsular effraction (P=0.046). The HER2 expression was correlated with histopathological type (P=0.001) and lymphovascular invasion (P=0.072), whereas Ki67 was correlated with pT (P=0.004) and regional lymph node (pN; P=0.033) (Tables 2 and 3). The correlating biomarkers were CK5/6 and E-cad (P=0.071).
(To view a larger version of Table 2, click here.)
(To view a larger version of Table 3, click here.)