Prognostic Factors in Patients with Locally Advanced Breast Cancer Treated by Neoadjuvant Chemotherapy

Article information

J Breast Dis. 2019;7(1):23-29
Publication date (electronic) : 2019 June 30
doi : https://doi.org/10.14449/jbd.2019.7.1.23
Department of Surgery, Chonnam National University Hwasun Hospital and Medical School, Hwasun, Jeollanam-do, Korea
Correspondence: Jung Han Yoon, M.D., Ph.D. Department of Surgery, Chonnam National University Hwasun Hospital and Medical School, 322 Seoyang-ro, Hwasun-eup , Hwasun-gun, Jeollanam-do 58128, Korea Tel: +82-61-379-7646, Fax: +82-61-379-7661, E-mail: jhyoon@jnu.ac.kr
Received 2018 September 5; Revised 2018 October 16; Accepted 2019 April 13.

Abstract

Purpose

Neoadjuvant chemotherapy (NAC) has become the standard treatment for patients with locally advanced breast cancer. The purpose of this study was to evaluate prognosis according to molecular subtype and clinicopathologic factors in patients with locally advanced breast cancer treated by NAC.

Methods

We retrospectively analyzed the medical records of 91 patients with breast cancer who underwent NAC followed by surgery between January 2005 and January 2010. The patients were classified into four molecular subtype groups: luminal A, luminal B, HER2 enriched, and triple negative (TN).

Results

Thirty-five (38%) patients had luminal A, 13 (14%) patients luminal B, 22 (24%) patients HER2 enriched and 21 (21%) patients TN breast cancer. Patients with TN breast cancer tended to be more than 50 years of age and to have a higher histologic grade. There were statistically significant differences according to ypN stage (ypN0 vs. ypN1–3; p=0.019, 5-year disease-free survival [DFS]; p=0.005, 5-year overall survival [OS]) and lymphovascular invasion (LVI) (p=0.003, 5-year DFS; p=0.006, 5-year OS) in the univariate analysis. In the multivariate analysis, LVI was a significant factor in 5-year DFS (odds ratio 2.145, 95% confidence interval 1.064–4.324, p=0.033). There was no significant difference among molecular subtypes in DFS (p=0.161) or OS (p=0.084).

Conclusion

LVI was associated with prognosis in patients with locally advanced breast cancer treated by NAC and surgery. However, molecular subtype had no effect on 5-year DFS or OS.

INTRODUCTION

Neoadjuvant chemotherapy (NAC) is increasingly being used for the benefits of tumor downstaging to facilitate breast-conservation therapy, to assess in vivo response to therapy, and to potentially downstage axillary lymph nodes (ALNs) [1-3]. NAC is also widely used in patients with early stage breast cancer. However, not all patients with breast cancer benefit from NAC. There may be identifiable subgroups that benefit more from this treatment than do other subgroups [4,5]. Therefore, numerous surrogate endpoints have been investigated in the setting of NAC. Rates of pathologic complete response (pCR) range from 16% to 20% according to the histologic subtypes of tumor and treatment modalities. Achievement of pCR has been correlated with better disease-free survival (DFS) and overall survival (OS) [6-8].

Recent studies have used gene expression profiling to classify breast cancers into distinct molecular subgroups and have suggested that this categorization could be used to predict prognosis. In patients treated with NAC, molecular subtype according to gene expression profiling could also effectively identify patients who are likely to achieve pCR [9-11]. The purpose of our study was to evaluate prognosis according to molecular subtype and clinicopathologic factors in patients with locally advanced breast cancer treated by NAC.

METHODS

We retrospectively analyzed the medical records of 135 patients with breast cancer who underwent NAC followed by surgery between January 2005 and January 2010. Exclusion criteria were distant metastases at diagnosis or inadequate follow up. In total, 91 patients were enrolled in this study.

All patients underwent core needle biopsy before surgery and surgical resection for breast cancer with sentinel lymph node biopsy (SLNB) and/or ALN dissection after NAC. The anthracycline- and taxane-based NAC regimens were chosen based on ALN involvement.

After completion of NAC, the patients underwent dynamic contrast-enhanced breast magnetic resonance imaging for measuring tumor size.

Patients were classified into the previously suggested immunohistochemistry (IHC)-based molecular subgroups as follows: luminal A (estrogen receptor [ER]-positive or progesterone [PR]-positive/human epidermal growth factor receptor 2 [HER2]-negative), luminal B (ER-positive or PR-positive/HER2-positive), HER2 enriched (ER-negative and PR-negative/HER2-positive), and triple negative (ER-negative, PR-negative, and HER2-negative). ER, PR, and HER2 were evaluated using standard avidin-biotin complex immunohistochemical staining methods. The ER and PR status was assessed using the Allred score, which was expressed as the sum of the proportion score and the intensity score of positively stained tumor cells. Tumors with an Allred score of at least 3 were regarded as positive. The intensity of HER2 staining was scored as 0, 1+, 2+, or 3+. Tumors with a 3+ score were classified as HER2 positive, and tumors with a 0 or 1+ score were classified as HER2-negative. In tumors with a 2+ score, gene amplification using silver in situ hybridization was used to identify HER2 status.

After completion of NAC, the size and extent of residual cancer were measured. The pCR was defined as the complete disappearance of invasive carcinoma in the breast and axilla. Residual ductal carcinoma in situ was included in the pCR category. All specimens were reviewed by an experienced pathologist.

Intraoperative subcutaneous injection of diluted indigo-carmine dye in the subareolar area was performed in the same fashion according to the surgeon’s standard SLNB practice.

Wilcoxon signed-rank tests, Kruskal-Wallis tests, Mann-Whitney U-tests, Fisher’s exact tests, logistic regression, Spearman’s correlations, and binary logistic regression analyses were used as appropriate. All variables were subjected to univariate analyses, and then the variables that were associated (p≤0.1) were analyzed in a stepwise multivariate logistic regression model. Analyses were performed using the SPSS version 19.0 statistical software package (IBM Corp., Armonk, USA), with p<0.05 considered significant.

RESULTS

This retrospective study included 91 female patients with a median age of 46 (27–78) years. Their mean body mass index was 24.0 kg/m2. A total of 59 patients (64.8%) underwent mastectomy, 89 patients (97.8%) underwent ALN dissection, 85 patients (93.4%) had invasive ductal or lobular carcinoma, and 43 patients (47.3%) were at clinical stage T4. The pCR rate was 8.8% (8 patients); however, 31 patients (34.1%) had stage ypN0 disease. The number of patients with positive ER, PR, and HER2 status were 44 (48.4%), 37 (40.7%) and 35 (38.5%), respectively. Lymphovascular invasion (LVI) was observed in 36 patients (40.0%), 87 patients (95.6%) were treated with taxane based NAC, 75 patients (82.4%) underwent radiation therapy, 43 patients (47.3%) underwent hormonal therapy, and 16 patients (17.6%) underwent trastuzumab therapy (Table 1).

Patients and tumor characteristics

Thirty five patients had luminal A, 13 had luminal B, 22 had HER2 enriched, and 21 had triple negative (TN) breast cancer. Most of the patients were in clinical stage 3, and 36 patients (39.6%) were in clinical stage 3B (Table 2). Patients with luminal A cancer tended to be less than 50 years of age (p<0.001) and had a middle histologic grade (p=0.04). Patients with luminal B, HER2-positive, and TN cancer tended to be more than 50 years of age (p<0.001) and had a high histologic grade (p=0.04). There was no statistically significant difference in laterality (p=0.612), clinical T stage (p=0.974), surgical method (p=0.253), ypT stage (p=0.591), ypN stage (p=0.15), or LVI (p=0.067) according to molecular subtype (Table 3). In this study, 6 patients showed pCR and patients with a high histologic grade tended to show pCR, but there was no statistical relation between pCR and other clinical factors such as; age, clinical stage, molecular subtype, LVI, recurrence, or death (Table 4).

Initial clinical stage according to tumor subtype

Clinicopathological characteristics according to tumor subtype

Patients characteristics with pathologic complete response

There were significant differences in 5-year DFS according to ypN stage (ypN0 vs. ypN1–3; p=0.019) and LVI (no vs. yes; p=0.003) in the univariate analysis. In the multivariate analysis, LVI was a significant factor in 5-year DFS (odds ratio 2.145, 95% confidence interval 1.064–4.324, p=0.033) (Table 5). There was a significant difference in 5-year OS according to ypN stage (ypN0 vs. ypN1–3; p= 0.005) and LVI (no vs. yes; p= 0.006) (Table 6). Molecular subtype was not a significant factor in 5-year DFS or 5-year OS, for which histologic grade had no meaning. We found no significant difference between molecular subtypes in 5-year DFS (p= 0.161) (Figure 1A) or 5-year OS (p= 0.084) (Figure 1B).

Univariate and multivariate analysis of prognostic factors for disease-free survival

Univariate and multivariate analysis of prognostic factors for overall survival

Figure 1.

(A) Disease-free survival (DFS) according to tumor subtype. (B) Overall survival (OS) according to tumor subtype.

DISCUSSION

Few studies have reported differences in tumor cellularity and treatment response patterns of four breast cancer molecular subtypes. Intrinsic differences between the histopathologic characteristics of these subtypes were confirmed in our study. Molecular classification based on gene expression profiling has led to a better understanding of the biological phenotypes of breast cancer [9,12]. This is useful in predicting chemo sensitivity as well as prognosis. However, the technical complexity and high costs of this procedure have limited its clinical application. Thus, a combination of immunohistochemical profiles (ER, PR, and HER2) has been investigated as a substitute for the molecular subtypes using gene-expression profiles, although these do not exactly correspond. In this study, we found that the IHC-based molecular subtypes effectively stratified breast cancer for predicting the likelihood of pCR to NAC.

Among the four IHC-based molecular subtypes, patients with the luminal A type (that is, hormone receptor-positive) breast cancer were less likely to achieve pCR [9]. A recent randomized phase II trial showed that neoadjuvant endocrine therapy is effective in ER-positive tumors, producing similar pCR rates as NAC, and better tolerability than NAC [13]. Therefore, neoadjuvant endocrine therapy may be a promising alternative strategy in luminal A breast cancer. In patients with HER2-positive cancer, recent phase III studies have shown that pCR rates were significantly improved with the addition of trastuzumab to conventional chemotherapy [14]. We also found that in patients with HER2-positive tumors, the pCR rate for the trastuzumab-treated group, was nearly twice that for the non-trastuzumab-treated group [15,16]. The differences between the two groups were statistically significant after adjustment for confounding factors. Taking these results together, we believe that trastuzumab should be incorporated into NAC for HER2-positive breast cancer. In patients with the TN subtype, because the prognosis of those who failed to achieve pCR is very poor, achieving the highest possible pCR may be particularly important. Therefore, increasing the efficacy of NAC by adding new drugs, such as platinum or poly ADP ribose polymerase inhibitors, might be required to improve the survival of this subgroup [17].

Several studies have reported the association of ALN status and the pathologic primary tumor response to NAC. In previous studies, the response rate of primary breast tumors was correlated with that of the lymph nodes, which were well correlated with DFS [18-20]. However, tumor size, histological grade, and HER2 status were not correlated with patient outcome. In the study of Rouzier et al. [21], high histologic grade and a greater than 50% response to chemotherapy were associated with negative conversion of ALN after NAC. Our results also showed that a high histologic grade and a better response of the primary breast tumor were associated with negative conversion of ALN (Table 6).

There are several limitations in our study. First, this was a retrospective study from a single center and the total number of patients was relatively small. A larger multicenter study with more patients is needed to validate our results. Second, we did not evaluate the recurrence of ALN after surgery because of the relatively short duration of follow-up. A follow-up study of ALN recurrence is needed for better understanding of cancer biology after NAC.

LVI was associated with DFS in patients with locally advanced breast cancer treated by NAC and surgery. However, molecular subtype had no effect on 5-year DFS or OS.

Notes

The authors declare that they have no competing interests.

References

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Article information Continued

Figure 1.

(A) Disease-free survival (DFS) according to tumor subtype. (B) Overall survival (OS) according to tumor subtype.

Table 1.

Patients and tumor characteristics

Characteristic Value (n = 91)
No. (%)
Age at diagnosis (yr)* 46 (27–78)
BMI (kg/m2)* 24.0 (18.6–31.6)
Surgical method
 Breast conserving surgery 32 (35.2)
 Mastectomy 59 (64.8)
Type of axillary surgery
 Sentinel lymph node biopsy 2 (2.2)
 Axillary lymph node dissection 89 (97.8)
Tumor histologic type
 Invasive ductal or lobular carcinoma 85 (93.4)
 Others 6 (6.6)
Clinical T stage
 cT1 5 (5.5)
 cT2 22 (24.2)
 cT3 21 (23.0)
 cT4 43 (47.3)
ypT stage
 T0 4 (4.4)
 Tis 4 (4.4)
 T1 36 (39.5)
 T2 39 (42.9)
 T3/T4 8 (8.8)
ypN stage
 N0 31 (34.1)
Nmic/N1 28 (30.8)
 N2 20 (22.0)
 N3 12 (13.2)
Estrogen receptor status
 Negative 47 (51.6)
 Positive 44 (48.4)
Progesterone receptor status
 Negative 54 (59.3)
 Positive 37 (40.7)
HER2 receptor status
 Negative 56 (61.5)
 Positive 35 (38.5)
Lymphovascular invasion
 Negative 54 (60.0)
 Positive 37 (40.0)
Neoadjuvant chemotherapy
 Taxane based 87 (95.6)
 Non-taxane 4 (4.4)
Radiation therapy
 Yes 75 (82.4)
 No 16 (17.6)
Hormonal therapy
 Yes 43 (47.3)
 No 48 (52.7)
Trastuzumab therapy
 Yes 16 (17.6)
 No 75 (82.4)

Results are shown as n (%) unless indicated otherwise.

BMI=body mass index; Nmic=node micrometastasis; HER2=human epidermal growth factor receptor 2.

*

median (range).

Table 2.

Initial clinical stage according to tumor subtype

Clinical stage Tumor subtype
Total (%)
Luminal A Luminal B HER 2 positive TN
2A 3 0 0 0 3 (3.3)
2B 0 1 0 1 2 (2.2)
3A 12 3 8 9 32 (35.2)
3B 18 4 6 8 36 (39.6)
3C 2 5 8 3 18 (19.7)
Total 35 13 22 21 91

TN=triple negative; HER2=human epidermal growth factor receptor 2.

Table 3.

Clinicopathological characteristics according to tumor subtype

Variables Tumor subtype
p-value
Luminal A (n=35) Luminal B (n=13) HER2 positive (%) (n=22) TN (n=21)
No. (%) No. (%) No. (%) No. (%)
Age (yr) < 0.001
 < 50 32 (91.4) 5 (38.5) 10 (45.5) 10 (47.6)
 ≥ 50 3 (8.6) 8 (61.5) 12 (54.5) 11 (52.4)
Laterality 0.612
 Right 20 (57.1) 9 (69.2) 11 (50.0) 10 (47.6)
 Left 15 (42.9) 4 (30.8) 11 (50.0) 11 (52.4)
Clinical T stage 0.974
 cT1–2 10 (28.6) 4 (30.8) 6 (27.3) 7 (33.3)
 cT3–4 25 (71.4) 9 (69.2) 16 (72.7) 14 (66.7
Surgery 0.253
 BCS 16 (45.7) 2 (15.4) 7 (31.8) 7 (33.3)
 Mastectomy 19 (54.3) 11 (84.6) 15 (68.2) 14 (66.7)
ypT stage 0.591
 ypT0, Tis 3 (8.6) 0 3 (13.6) 2 (9.5)
 ypT1–4 32 (91.4) 13 (100) 19 (86.4) 19 (90.5)
ypN stage 0.150
 ypN0 11 (31.4) 2 (15.4) 7 (31.8) 11 (52.4)
 ypN1–3 24 (68.6) 11 (84.6) 15 (68.2) 10 (47.6)
Histologic grade 0.040
 I 8 (23.5) 1 (7.7) 2 (10.6) 1 (4.8)
 II 20 (58.8) 5 (38.5) 7 (36.8) 8 (38.1)
 III 7 (17.7) 7 (53.8) 13 (52.6) 12 (57.1)
LVI 0.067
 No 17 (48.6) 6 (46.2) 14 (66.7) 17 (81.0)
 Yes 18 (51.4) 7 (53.8) 8 (33.3) 4 (19.0)

BCS=breast conserving surgery; TN=triple negative; HER2=human epidermal growth factor receptor 2.

Table 4.

Patients characteristics with pathologic complete response

Age (yr) Clinical stage Molecular subtype Histologic grade LVI Recurrence Death
44 IIIB TN III No No No
47 IIIA HER2 (+) Unknown No No No
46 IIB Luminal A III Yes No No
66 IIIC HER2 (+) II No No No
57 IIIC TN II No No No
70 IIIC HER2 (+) II No Yes Yes

LVI=lymphovascular invasion; TN=triple negative; HER2=human epidermal growth factor receptor 2.

Table 5.

Univariate and multivariate analysis of prognostic factors for disease-free survival

Variables Univariate
Multivariate
5-year DFS (%) p-value RR (95% CI) p-value
Age (< 50/ ≥ 50 years) 53.0/71.0 0.162
Surgery (BCS/mastectomy) 62.8/57.8 0.472
cT stage (cT1–2/T3–4) 60.5/58.9 0.439
ypT stage (ypT0/Tis/T1–4) 68.6/58.8 0.552
ypN stage (ypN0/N1–3) 77.5/50.5 0.019 1.745 (0.75–4.058) 0.196
LVI (no/yes) 71.3/40.5 0.003 2.145 (1.064–4.324) 0.033
Histologic grade (low/high) 61.4/59.8 0.786
Radiation therapy (no/yes) 74.5/56.1 0.162
Hormone therapy (no/yes) 64.2/54.9 0.877

BCS=breast conserving surgery; RR=risk ratio; LVI=lymphovascular invasion.

Table 6.

Univariate and multivariate analysis of prognostic factors for overall survival

Variables Univariate
Multivariate
5-year OS (%) p-value RR (95% CI) p-value
Age (< 50/ ≥ 50 years) 80.4/83.2 0.544
Surgery (BCS/mastectomy) 88.1/78.4 0.133
cT stage (cT1–2/T3–4) 86.7/79.5 0.496
ypT stage (ypT0/Tis/T1–4) 66.7/82.7 0.769
ypN stage (ypN0/N1–3) 96.2/74.2 0.005 3.491 (0.936–13.028) 0.063
LVI (no/yes) 91.6/65.7 0.006 2.193 (0.875–5.497) 0.094
Histologic grade (low/high) 78.8/82.2 0.789
Radiation therapy (no/yes) 87.1/80.2 0.781
Hormone therapy (no/yes) 78.8/84.5 0.866

BCS=breast conserving surgery; RR=risk ratio; LVI=lymphovascular invasion.