Effects of clinicopathological factors on prognosis of young patients with breast cancer

Objective: This study aims to analyze the relationship between clinicopathological characteristics and survival in young patients (≤ 35 years old) with breast cancer. Results: Compared with patients aged 30 to 35 years, age of younger patients (≤ 30 years) was an independent predictor for poor disease-free survival (DFS) and overall survival (OS). PR negative status (p = 0.042), high tumor grade (p = 0.012), and advanced lymph nodes post-surgery (p < 0.001) were independent prognostic factors of DFS, while PR negative status (p = 0.003) and advanced lymph nodes post-surgery (p = 0.002) were both independent prognostic factors of OS. For patients with hormone receptor-positive breast cancer, people with ER+ or PR+ and HER2−/+ status showed poorer prognosis than the other two levels. Risk factor grouping based on the ER, PR, HER2, Ki-67 status, tumor grade, and lymph nodes post-surgery showed that patients in highest score group received the poorest prognosis. Materials and Methods: A total of 173 cases of young breast cancer patients were included in this study. The clinicopathological factors potentially associated with prognosis were evaluated by univariate and multivariate analyses. Furthermore, we categorized patients into different groups to evaluate the prognosis according to hormone receptor status or important risk factors. Conclusions: Patient age, PR status, tumor grade, and lymph nodes post-surgery had clinical value as predictive factors of prognosis. Grading system based on the hormone status or the risk factor grouping may offer a useful approach to assess which subgroups of young breast cancer patients present poorer prognosis.


INTRODUCTION
Breast cancer, one of the most commonly diagnosed cancer in women worldwide, affects more than 1.3 million individuals and accounts for about 14% of cancer-related deaths [1,2].Approximately 6.6% of breast cancer patients are diagnosed in women younger than 40 years, 2.4% in those younger than 35, and 0.65% in those younger than 30 [3].However, in China, the reported cases in women younger than 35 years are markedly higher than those in western countries [4,5].Moreover, the increase in young breast cancer patients is highly problematic, and the behavior of these tumors is more aggressive [6].Young women with breast cancer are likely to present advanced stages at diagnosis, including higher histologic grade, larger tumor size, more aggressive pathological characteristics, and higher rates of recurrence at any clinical stage in comparison with their older counterparts [7].Although several large-scale studies have reported that young age ( ≤ 35) is an independent prognostic factor for both disease-free survival (DFS) and overall survival (OS) [8,9], few studies focused on the impact of clinical and pathologic factors on the prognosis in young breast cancer patients.This study aimed to evaluate the prognostic significance of clinicopathological factors stratified by age, surgery type, molecular subtype based on estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) statuses.In addition, considering that hormone receptor-positive breast cancer is the main subtype in young patients, we divided hormone receptor-positive breast cancer into different groups to assess the prognostic influence on young patients.

Clinicopathological factors and outcome
According to the 2013 St. Gallen expert consensus, the molecular subtypes of all the 173 cases were divided into 5 types: 27 cases were classified into luminal A subtype (15.6%), 57 cases into Luminal B (HER2-) subtype (32.9%), 38 cases into Luminal B (HER2+) subtype (22.0%), 19 cases into HER2 subtype (11.0%), and 32 cases in to TNBC subtype (18.5%), with 128 (74.0%) patients undergoing mastectomy while 45 (26.0%) patients received breast-conserving surgery (BCS).The median age of all patients was 32, within median follow-up time of 64 months.Tumor relapse occurred in 59 cases, among which 42 cases died.The clinical and pathologic characteristics of the 173 patients included in this study are shown in Table 1.
In univariate analysis, PR status, tumor grade, lymph nodes post-surgery, and histological grade were significantly associated with DFS and OS.In addition, patients younger than 30 was associated with significantly shorter DFS and OS compared with patients aged from 30 to 35 (p = 0.019 and p = 0.011, respectively, Table 1, Figure 1A, 1B).As shown in Table 4, in multivariate analysis, patient age (p = 0.002), PR status (p = 0.042), tumor grade (p = 0.012), and lymph nodes post-surgery (p < 0.001) were independent predictors of DFS for young patients, whereas patient age (p = 0.002), PR status (p = 0.003), and lymph nodes post-surgery (p = 0.002) were correlated with OS.In both univariate and multivariate analyses, the classification of patient age was an independent predictor for DFS and OS (Figure 1A and 1B and Tables 2 and 4), indicating that patients younger than 30 shows a poorer prognosis compared with patients aged 31 to 35.We analyzed the clinical and pathologic factors between the two groups at diagnosis, as shown in Table 2, the expression levels of ER, PR, HER2, and Ki-67, tumor size, lymph nodes postsurgery, molecular subtype, and treatment condition did not display any difference between women aged 31 to 35 and women younger than 30 years of age.

Local therapy, age, and survival
We evaluated the effect of surgery type, including BCS and mastectomy, on DFS and OS in young patients with T1-T2N0-N+M0 breast cancer.A total of 146 patients were considered, with 101 patients undergoing mastectomy and 45 undergoing BCS.No connection was observed between surgery type and cumulative probability of DFS (P = 0.120) or OS (P = 0.140).Moreover, the effectiveness of surgery type stratified by age on DFS and OS were analyzed.Compared with patients aged 30-35 years, patients below 30 years of age were associated with lower DFS after mastectomy (P = 0.007) but not associated with OS (P = 0.204).No statistically significant difference in both DFS and OS after BCS was observed between patients aged form 31 to 35 and patients younger than 30 years old (P = 0.345, and P = 0.755, respectively).

Prognosis and receptor-positive breast cancer or risk factors grouping
The hormone receptor levels were 1, 2, and 3 in 59 (48.4%), 24 (19.7%), and 39 (32.0%) of the 122 patients with hormone receptor-positive breast cancer, respectively.In univariate analysis, hormone receptor level was an independent prognostic factors for both DFS and OS (p = 0.002; Figure 2A, 2B, Table 3).Young breast cancer patients with ER+, PR+, and HER2− received the best prognosis, whereas the group of ER+ or PR+, HER2−/+ patients had the poorest prognosis in hormone receptorpositive patients.In the present study, the risk factor group based on ER, PR, HER2, and Ki-67 status, tumor grade, and lymph nodes post-surgery were 1, 2, and 3 in 125 (72.3%), 38 (22%), and 10 (5.8%) of the 173 patients, respectively.Patients in risk group 3 were predicted to present the poorest DFS and OS (p < 0.001; Figure 3A, 3B, Table 3).All of the 10 patients in group 3 progressed, and 8 patients died.In multivariate analysis, hormone receptor level was an independent prognostic factor for DFS (p = 0.038), and the risk factor group was an interrelated prognostic predictor of DFS and OS in young patients (p = 0.006, and p = 0.010, respectively; Table 4).

DISCUSSION
Previous studies have shown that young age (≤ 35 years old) is an adverse prognostic factor for women with breast cancer; moreover, compared with older patients, younger breast cancer patients present later disease stage, higher grade tumors (poorer and more undifferentiated tumors), and poorer receptor status [13,14].However, relatively few studies focused on the prognostic effect of clinicopathologic factors among young breast cancer patients.In the present study, we selected several common clinical and pathological factors, including patient age, ER, PR, HER2, Ki-67 status, tumor histological grade, tumor grade, lymph nodes post-surgery, molecular subtype, and treatment condition, which were possible predictors of cancer outcomes.The results implied that patient age, PR status, tumor grade, and lymph nodes post-surgery were associated with DFS, whereas patient age, PR status,   and lymph nodes post-surgery were associated with OS.Older age (30-35) suggested better prognosis, whereas PR negative status, large tumor grade, and advanced lymph nodes post-surgery were associated with poorer prognosis.
It has been generally recognized that young age itself is an independent risk factor for recurrence and death.A study based on a national population cancer registry showed that young age is an independent risk factor for death (HR = 1.095) [15].Peng et al. [16] retrospectively analyzed a large cohort of 511 young breast cancer patients aged ≤ 35 years by comparing clinicopathological characteristics with a cohort of 551 older patients aged from 35 to 50 years old, and their results showed that younger patients present significantly shorter DFS than their older counterparts (median 23.2 months versus 28.4 months, p = 0.024).However, few studies discussed the prognostic effect of age in young breast cancer patients.A trial referring to age ≤ 40 years as young breast cancer revealed that patient age of younger than 35 years (as opposed to 35-40) was an independent risk factor for poorer local relapse-free survival, DFS, and OS [17].Moreover, Zhao et al. [3] reported that patients who were younger than 30 presented poorer prognosis compared with patients aged from 31 to 35.In our study, patient age showed a significant correlation with both DFS and OS in young patients, and patients younger than 30 years of age showed an adverse prognosis compared with patients aged from 31 to 35; this finding was consistent with those of the previous study.Moreover, the results showed no difference between age and clinicopathological factors in the two groups when classified by age; again, these results were consisted with those of a previous study [17].
Given that young women with breast cancer are known to have a higher risk of local recurrence and mortality, the impact of surgical treatment on outcomes in young breast cancer patients remains unclear, and BCS in young patients remains to be a controversial issue [18].Several studies suggested that young women (younger than 35 or 40 years) show inferior cosmetic outcomes with BCS, implying that these women may be better served by mastectomy [19].However, Quan et al. [18] reported similar oncologic outcomes in a cohort of young women (≤ 35) who were selected for treatment with BCS and mastectomy.Besides, an meta-analysis carried out on 22598 patients showed that mastectomy unlikely provides better OS compared to BCS in early young breast cancer patients [20].In the present study, our results demonstrated no differences in DFS and OS between BCS and mastectomy in young breast cancer patients.When surgery type was stratified by age, compared with patients aged from 30 to 35 years, patients aged ≤ 30 years was associated with lower DFS after mastectomy but not associated with OS.These results may suggest that BCS is a rational option as surgery type for young women.However, patients included in this cohort had 84.4% T1/ T2 tumors, but only 45 cases (26.0%) received BCS.A nationwide survey indicated that in developed urban areas in China, BCS were performed on only 24.3% in 2008, which is much lower compared with western countries [21].One explanation for this is lack of resources for radiation therapy, especially in less developed regions in China [22].Hence readers should be cautious referring to the result considering the limited patient number that received BCS.
A previous study observed that a negative PR status occurs more frequently in young breast cancer patients [23].In addition, PR is known to be regulated by the estrogen receptor α (ERα), and loss of PR expression indicates a more aggressive disease phenotype, which is less dependent on estrogen signaling [11].Mohammed et al. reported that PR lacks proliferative potential; importantly PR is an anti-proliferative factor in an estrogen-driven context [24].Besides, PR+ status distinctly improves outcome prediction over ER status alone for patients who receive adjuvant endocrine therapy, and several studies confirmed that the absence of PR is an independent risk factor for DFS or OS [25].In our study, we detected that PR negative status was an independent risk factor and was significantly associated with a more unfavorable DFS and OS in both univariate and multivariate analyses.By contrast, ER expression was not typically related with prognosis, as was consistent with the results of previous studies.
The molecular subtypes of breast cancer are considered to reflect tumor biology and exert a vital influence on prognosis.Patients with luminal A subtype are likely to receive the best prognosis than the other three subtypes [26].The proportion distribution of molecular subtypes is different in young breast cancer patients and, young breast cancer patients present a higher rate of triple-negative and HER2 overexpression subtypes compared with the older patients [15].Villarreal-Garza C et al. [27] reported that young women diagnosed with hormone receptor-positive breast cancer in Mexico were more specifically categorized as luminal B, experiencing poor survival outcomes.In our study, IHC surrogate for luminal B was the most common, account for more than half of all cases.Moreover, considering that hormone receptor-positive breast cancer remains to be the major subtype among young patients [28], we categorized the hormone-positive breast cancer into three levels, and the results showed that ER+, PR+, HER2− showed better prognosis compared with the other two kinds, and ER+ or PR+, HER2−/+ exhibited the poorest prognosis among the three subtypes.
ER, PR, HER2, and Ki-67 status, tumor grade, and axillary lymph nodes involved post-surgery are combined to determine a prognostic parameter [3].In our study, the risk factor-based combination classification were divided into three groups, and the results revealed that the risk score group was an independent prognostic predictor, with  the risk of disease progression and death increasing by 1.818 and 1.953 times, respectively.This finding indicated that the risk grouping score may be helpful in selecting patient subgroups for further adjuvant treatment.

Patients and follow-up
A total of 1796 patients with histologically confirmed breast cancer with surgical resection in West China Hospital of Sichuan University were confirmed from 2010 to 2012.Among these patients, a total of 173 patients younger than age 35 without distant metastasis at first diagnosis were included in this retrospective study.Patients were investigated and followed up every 3 months for 3 years, every 6 months for 5 years, and every 12 months in 6-10 years after operation.The examination of carcinoembryonic antigen (CEA) and carbohydrate antigen 153 (CA153), breast ultrasound, and mammography, liver ultrasound, chest X-ray, head CT scanning, and gynecological examination were included.This study was approved by the Research Ethics Committee of West China Hospital of Sichuan University.

Classification of hormone receptor and assessment of risk factor scores
Breast cancer patients were treated according to ER and HER2 status in clinical setting.ER+ tumors typically respond to hormone therapy, whereas HER2+ tumors respond to anti-HER2 therapy.Given its nature as a highly heterogeneous disease with different histology, gene expression profiles, or mutation, hormone-positive breast cancer usually presents various clinical courses and responses to systemic treatment [3].PR is another molecular marker that may be used in the clinic, as loss of PR in ER+ tumors is thought to be predictive for the lack of response to hormone therapy [11].Besides, variability in Ki-67 scoring was observed in several of the world's most experienced laboratories and significant interobserver variability were detected due to limited analytical validity [12].According to a previous study, we hereby classified hormone receptor-positive breast cancer as level 1 (ER+, PR+, HER2−), level 2 (ER+, PR+, HER2+), or level 3 (ER+ or PR+, HER2−/+) based on the ER, PR, and HER2 status and regardless of the expression of Ki-67 [3].Patients with level 2 and level 3 tumors were considered to be at a more aggressive state and were treated with more chemotherapy than level 1, whereas level 1 subgroup received more endocrine therapy than the other two levels.
A total of 173 patients were divided into three groups based on the scores of important risk factors including ER, PR, HER2, and Ki-67 status (ER−, PR−, and HER2+, and Ki-67+, one point each), tumor grade (grade 1 is considered as one point, and so on), and lymph nodes post-surgery (0 for no positive node, 1 for 1-3 positive nodes, 2 for 4-9 positive nodes, and 3 for ≥10 positive nodes).Group 1 was scored 1-4, group 2 was scored 5-6, and group 3 was scored 7-10, respectively.

Statistical analysis
DFS was defined as the time from diagnosis to the date of disease relapse, death, or last follow-up.OS was calculated from the time of diagnosis to death as a result of recurrence events or last follow-up, whichever occurred first.The follow-up deadline was March 2017.The relationship between the different age groups and the clinicopathological factors was analyzed by χ 2 test.The end-points were estimated using the Kaplan-Meier method, and the differences between survival curves were tested using the log rank test.Univariate and multivariate analyses with the Cox proportional hazard regression model were performed to assess the influence of potential confounders on DFS and OS.The crude hazard ratios (HR) and corresponding 95% confidence intervals (CIs) were reported.Statistical analyses were performed using the SPSS (version 20.0) software package (SPSS Inc., Chicago, IL, USA).P < 0.05 was considered statistically significant.

CONCLUSIONS
In conclusion, this study shows that compared with their older counterparts, patients younger than 30 years at diagnosis with breast cancer constitute an independent risk factor for decreased DFS and OS among young patients (≤ 35 years).Both PR status and lymph nodes involved post-surgery present clinical value as predictive factors of patient prognosis; moreover, we hope that the grading system based on hormone level and risk factor grouping may serve a useful index for evaluating the risk of breast cancer in young women to identify subgroups of patients with poor prognosis and offer therapeutic strategies for young breast cancer patients.

Figure 1 :
Figure 1: Kaplan-Meier survival analyses of correlations between age and survival among breast cancer patients.PFS (A) and OS (B).

Figure 2 :
Figure 2: ER, PR, HER2 status and survival.Kaplan-Meier survival analysis on DFS (A) in accordance with ER, PR, and HER2 status.Kaplan-Meier survival analysis on OS (B) in accordance with ER, PR, and HER2 status.

Figure 3 :
Figure 3: Risk factor grouping and survival.DFS by Kaplan-Meier survival analysis (A) in accordance with risk factor grouping.OS by Kaplan-Meier survival analysis (B) in accordance with risk factor grouping.

Table 1 : Clinicopathological characteristics and outcomes among young breast cancer patients
BCS: breast conserving surgery; TNBC: triple-negative breast cancer; DFS: disease-free survival; OS: overall survival.

Table 2 : Patient and tumor characteristics by age group
BCS: breast conserving surgery; TNBC: triple-negative breast cancer.