All 98 patients included in the study were diagnosed with stage IV metastatic HER2-positive breast cancer. The average age of these individuals was 50.1 ± 10.3 years, ranging from 30 to 79 years, with 51% being postmenopausal. The mean follow-up duration was 97.9 ± 53.8 months (12-237.4 months). Out of the patients, 26.5% survived, while 73.5% had succumbed at the time of data analysis. The distribution of tumor localization was as follows: 45 cases in the right breast, 50 in the left, and 3 cases (3.1%) had bilateral breast tumors. The surgical procedures performed included breast-conserving surgery with axillary dissection in 34 patients (34.7%), modified radical mastectomy with axillary dissection in 29 patients (29.6%), and tumor excision or toilet mastectomy in 35 patients (35.7%). The predominant type of tumor was invasive ductal carcinoma (76.5%), with 4.1% classified as grade 1, 57.1% as grade 2, and 38.8% as grade 3. Axillary lymph node dissection was carried out in 73.5% of cases, revealing lymph node metastasis in 65.2% of these situations. Among cases with lymph node metastasis, capsular invasion was present in 75.5% of them. Treatment response analysis indicated a complete response in 24.5% of patients, partial response in 61.2%, and stable response or progressive disease in 14.3%. The clinical characteristics and histopathologic features of the included patients are shown in Table 1. Kaplan Meier Survival analyses identified a statistically significant relationship between overall survival and complete response to treatment, with a log-rank p-value of 0.008 (Fig. 2). The mean progression-free survival (PFS) was 50.3 ± 26.9 months (1-163 months), and the mean overall survival (OS) was 88.8 ± 59.4 months (12–272 months). Disease-specific survival (DSS) was over 5 years in 54.1% of cases and under 5 years in 45.9% of cases. Furthermore, 31.6% of patients survived over 10 years, and a correlation was found between younger age and improved overall survival (p = 0.006) (Fig. 3).
Table 1
Demographic and histopathologic features of patients.
PARAMETERS
|
STATUS
|
N
|
%
|
Prognosis
|
Survived
Exited
|
26
72
|
26.5
73.5
|
Tumor Location
|
Right
Left
Bilateral
|
45
50
3
|
45.9
51
3.1
|
Diagnosis
|
Invasive Ductal Carcinoma (İDC)
Invasive Lobular Carcinoma (İLC)
Mixt IDC and ILC
Invasive Papillary Carcinoma
Other histologic variants
|
75
4
5
4
10
|
76.5
4.1
5.1
4.1
10.2
|
Grade
|
Grade 1
Grade 2
Grade 3
|
4
56
38
|
4.1
57.1
38.8
|
Type of Surgery
|
Breast conserving surgery with axillary dissection (AD)
Modified radical mastectomy with AD
tumor excision or toilet mastectomy
|
34
29
35
|
34.7
29.6
35.7
|
Adjuvant Radiotherapy
|
Yes
|
51
|
52.0
|
Axillary lymph node dissection
|
Yes
|
72
|
73.5
|
Therapy responds
|
Complete response
Partial response
Stable disease
Progressive disease
|
24
60
8
6
|
24.5
61.2
8.2
6.2
|
Visceral organ metastasis
|
Present
Absent (only lymph node, soft tissue, skin or bone metastasis)
|
48
50
|
49.0
51.0
|
Histopathologically confirmed lymph node metastasis
|
Present
|
47
|
47.9
|
Capsular invasion in the metastatic lymph nodes
|
Present
|
37
|
37.7
|
Lymphovascular invasion
|
Present
|
38
|
38.8
|
In the immunohistochemical examinations, ER-positivity was identified in 67 cases (68.3%) and PR-positivity in 51 cases (52%). In 68 cases (69.4%), either ER or PR positivity was confirmed. C-erbB2 positivity rate ranged from 20–100%, with a mean of 76.1% ± 22.7%, while the Ki-67 proliferation index ranged from 15–90%, with a mean of 34.7% ± 22. Evaluation of immune profiles of TILs could be conducted in only 39 cases, all of which exhibited CD3 expressed T lymphocytes and at least one FOXP3 positive regulatory T cell (TREG) in the TILs (Table 2). CD3 and FOXP3 staining was performed in a subset of 39 cases, with 14 (35.8%) classified as patients with LTS and 28 (71.7%) as patients with LTR. Statistical analysis revealed that LTS patients had higher levels of CD3 expressed T cells and a denser presence of FOXP3 positive TREGs within the TILs, with both demonstrating statistical significance (Fig. 4), (log-rank, p = 0,025). Conversely, there was no association observed between LTR and CD3 or FOXP3 expressions.
Table 2
Immunohistochemical and molecular findings
PARAMETERS | STATUS | N | % |
ER status | Positive | 67 | 68.3 |
PR status | Positive | 51 | 52.0 |
ER and/ or PR positivity | Yes | 68 | 69.4 |
C-erbB2 expression | 2+ 3+ | 9 89 | 9.2 90.8 |
HER2 amplification (by FISH) | Positive | 10 | 10.2 |
Ki67 proliferation index | 15–29 ≥ 30 | 81 17 | 82.7 17.3 |
CD3 expressed T cells (in 39 cases) | Low High | 18 21 | 46.2 53.8 |
FOXP3 expression (in 39 cases) | < 10/ HPF 10–49/HPF ≥ 50/ HPF | 26 13 0 | 66.7 33.3 0 |
The results of the Cox proportional hazards model, displaying the impact of various parameters on DDS-associated outcomes, were summarized in Table 3. Upon conducting statistical analyses, it was observed that factors including menopausal status (p = 0.925), visceral/non-visceral involvement (p = 0.710), presence of local recurrence (p = 0.668), adjuvant CT (p = 0.189), adjuvant RT (p = 0.255), adjuvant HT (p = 0.792), and type of surgery (excision/breast preservation/radical mastectomy p = 0.715) did not demonstrate significance (Fig. 5).
Table 3
Cox proportional hazards model of LTR patients (N = 53, 54.1%).
Parameters Method: enter | HR (95% CI) | p value |
Age 65 + years < 65 years | Reference 2.7 (1.3–5.3) | 0.004 |
Complete response Yes No | Reference 0.058 (0.028–0.121) | < 0.001 |
Trastuzumab treatment > 2 years < 2 years | Reference 0.078 (0.018–0.337) | 0.001 |
Hormone receptor-positive Positive Negative | Reference 1.2 (0.729–2.048) | 0.444 |
CD3- positive cells Low High | Reference 1.025 (0.984–1.067) | 0.241 |
FOXP3- positive cells Low High | Reference 0.964 (0.881–1.056) | 0.434 |
Notably, in cases showing long-term response, only complete and partial responses to the initial multidisciplinary treatment were deemed significant influencers of survival (p = 0.008). It is interesting to note that out of 24 patients displaying a complete response to the first-line treatment, 17 were alive (70.8%), while out of 57 patients with a partial response, only 16 were alive (28%). Overall, individuals who were younger (p = 0.006), exhibited higher CD3-positivity (p = 0.041), displayed elevated FOXP3-positivity (p = 0.025), and demonstrated complete or partial response to treatment (p = 0.008), as well as prolonged response to trastuzumab treatment (p = 0.001), were associated with longer survival.