Association of Breast Cancer Subtypes and Clinicopathological Factors with Axillary Lymph Node Positivity Amongst Women with Breast Cancer in Rajasthan: An Observational Analytical Study

Abstract

Prognostic factors by definition, are capable of providing information on clinical outcomes at the time of diagnosis, independent of therapy. The number of positive lymph nodes (number of ipsilateral axillary nodes with metastatic tumour deposits) is a strong and independent prognostic factor in breast cancer. In a meta-analysis (New England Journal of Medicine, 2017) of over 62,000 patients, the risk of distant recurrence over years 5 to 20 for those with T1 tumours was 13% in the absence of lymph node involvement, 20% among those with one to three involved lymph nodes, and 34% among those with four to nine involved nodes. In this study, we analyzed the association of clinicopathological factors and breast cancer subtypes with axillary lymph node (ALN) positivity in women with breast cancer in Rajasthan. A multivariate Logistic (Ordinal) Regression Model was used to predict the number of positive lymph nodes based on independent variables that showed 90% significance in bivariate analysis, such as total number of lymph nodes dissected, tumour necrosis, and lymphovascular invasion. The Wald criterion indicated that only LVI had a significant impact on the prediction (p < 0.05), while tumour necrosis and the total number of lymph nodes dissected were not significant predictors (p > 0.05). Patients with LVI had a 43.47 times higher risk of having positive lymph nodes (p < 0.05). Early prediction of lymph node metastasis through LVI testing can help in prognostication. Breast cancer subtypes should not be a criterion while deciding lymph nodal management.

Introduction

According to the Global Cancer Observatory, breast cancer is the most common cancer among women globally, with approximately 2.3 million new cases and 685,000 deaths reported in 2020 [1]. Recurrence at the primary or distant site is a leading cause of mortality, with the number of positive lymph nodes being a strong and independent negative prognostic factor.

Amongst women with no evidence of metastatic disease (M0), the 5-year survival rate for those who present with localized (breast only) versus regional disease (pathologic node involvement) is 99 and 85%, respectively [2]. Even small tumours (< 2 cm) have a worse prognosis in the presence of pathologic node involvement. Axillary lymph node involvement is a critical prognostic factor for breast cancer, indicating the likelihood of disease spread and determining the stage of cancer [3]. Breast cancer patients in India have a high incidence of axillary lymph node involvement, ranging from 30 to 70%. In Rajasthan, studies have revealed that 40–70% of breast cancer patients have axillary lymph node (ALN) positivity, which is linked to a lower survival rate and poor prognosis [4–6].

Breast cancer prognosis is influenced by various clinicopathological factors including age, menopausal status, tumour size, histological grade, the presence of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Immunohistochemistry (IHC) is used to classify tumours into different breast cancer subtypes. In Indian women, studies have explored the connection between ALN positivity and these factors [7–9]. This study aims to determine if the number of positive lymph nodes differs based on clinicopathological factors and breast cancer subtypes (based on immunohistochemistry) amongst women from Rajasthan. This is crucial in improving the risk stratification and management of cancer [7].

Materials and Methods

This observational analytical study was conducted at a tertiary care hospital in the capital city of Rajasthan from 2019 to 2021. The study cohort included 140 breast cancer patients who underwent breast cancer surgeries (modified radical mastectomies) under the Department of Surgical Oncology.

The inclusion criteria for the study were women who were born in Rajasthan and presented with invasive breast cancer, Stage I–III. These women gave informed consent, underwent modified radical mastectomy (MRM), and had a minimum of 10 lymph nodes dissected. Patients who did not give consent, presented with metastasis, had a history of radiation therapy or had undergone neoadjuvant chemotherapy were excluded from the study. Every patient suitable for neoadjuvant therapy was adequately persuaded to undertake the treatment. The risk benefit ratio was extensively explained. The patients with Stage III locally operable breast cancer or triple negative/Her2 + subtypes with stage I and II who still opted for adjuvant therapy instead of neoadjuvant therapy were included in this study. Patients with cn2 or cN3 who underwent neoadjuvant therapy were not included in the study.

The clinicopathological profiles of patients were analyzed: including their age, menopausal status, the total number of lymph nodes dissected, the number of positive lymph nodes, tumour histological type, pathological tumour size, pathological tumour stage, tumour grade, tumour necrosis, Modified Bloom Richardson (MBR) score, lymphovascular invasion (LVI), breast cancer subtypes based on hormonal status (estrogen and progesterone receptors ER/PR) as well as Human Epidermal Growth Factor Receptor (HER2) expression. All of this information was tabulated and analyzed.

According to the American Joint Committee on Cancer Eighth Edition (AJCC), the presence of cancer cells in the axillary lymph nodes (ALN) was classified as pN0 (no involvement), pN1 (involvement in 1–3 ALN), pN2 (involvement in 4–9 ALN), or pN3 (involvement in 10 or more ALN). Tumour staging was determined based on the AJCC 8th edition and classified according to TNM (Tumor Node Metastasis). The size of the tumours was measured differently than the standard T staging of TNM. It was categorized as less than 2 cm, 2–4 cm, and more than 4 cm for better calculations since most of the tumours fell under T2. To determine the degree of tumour differentiation, the Elston Ellis grading system was used. This system assesses the percentage of tubule formation, nuclear pleomorphism, and mitotic activity.

Based on immunohistochemistry (IHC) analysis, four breast cancer subtypes were identified. Luminal A subtype (ER + , PR + , HER2 − , with low expression of genes related to proliferation), Luminal B subtype (ER + , PR + , HER2 + , with higher expression of proliferation clusters), Non-Luminal subtype which was HER2 enriched (ER − , PR − , HER2 +), and Triple Negative subtype (ER − , PR − , HER2 −).

The 2018 ASCO/CAP [American Society of Clinical Oncology (ASCO)/College of American Pathologists] update was used to report HER2 positivity. If a homogenous, dark circumferential (chicken wire) pattern was present in over 10% of invasive tumour cells and received an IHC score of 3 + , this indicated a positive HER2 result. All tumours with an IHC score of 3 + were considered HER2 positive. If there was incomplete and/or weak/moderate, circumferential membrane staining within over 10% of tumour cells, this received an IHC score of 2 + . All tumours with an IHC score of 2 + were reported as equivocal. An IHC score of 1 + was given if there was faint or barely perceptible, incomplete membrane staining within over 10% of tumour cells, and these tumours were reported as HER2 negative. If no staining was observed or there was incomplete membrane staining within less than 10% of tumour cells, an IHC score of 0 was given and these tumours were also reported as HER2 negative. If HER2 testing produced ambiguous results, further testing was triggered using in situ hybridization (ISH) on the same specimen. Additionally, if the sample showed strong membrane staining of normal breast ducts, if artefacts affected most of the sample, or if controls did not produce the expected results, HER2 testing was repeated using Fluorescent In situ hybridization (FISH). Before counting at least 20 cells, the entire ISH slides were scanned, or IHC was used to identify areas of potential HER2 amplification. Results from ISH were determined by calculating the ratio of gene amplification between HER2 and the chromosome 17 enumeration probe (CEP17). If the HER2/CEP17 ratio was >  = 2.0 and the HER2 copy number signals/cell was >  = 4, the result was reported as ISH positive (HER2 +). If both of these characteristics were not present, the result was reported as ISH negative (HER2 −).

If there was a discrepancy between the two variables, a blinded observer was recruited to repeat the test based on previous ISH results. Additionally, if there was a second population of cells with increased HER2 signals/cell and consisting of over 10% of tumour cells on the slide, at least 20 overlapping cells were counted separately and reported. If the average count was less than 4.0 HER2 signals/cell and the HER2/CEP17 ratio was equal to or greater than 2.0, the pathologist diagnosed HER2 as negative and included a comment. If the HER2/CEP17 ratio remained less than 2.0 with six or more HER2 signals/cell, the diagnosis was HER2 positive. If the average count was equal to or greater than 4.0 and less than 6.0 HER2 signals/cell with a HER2/CEP17 ratio less than 2.0, the pathologist diagnosed HER2 as negative and included a comment.

Similarly, according to ASCO/CAP [American Society of Clinical Oncology (ASCO)/College of American Pathologists], ER/PR was considered positive if more than 1% of tumour cells showed nuclear staining. It was considered negative when ER/PR expression was less than 1% on IHC and it was either 0 to + 1 by IHC. It was also considered negative if IHC 2 + and fluorescence in situ hybridization (FISH) negative (not amplified).

Statistical Analysis

Data was collected and entered into a Microsoft Excel spreadsheet. Patients with missing values for more than three variables were excluded from the study. Patients with missing values for one or two variables were included in the final analysis.

We analyzed the data by summarizing discrete data as proportions and using the Chi-square test. For continuous data, we calculated the mean and standard deviation and used the One-Way ANOVA test. We categorized patients based on the number of positive lymph nodes into four groups: the first group had no positive lymph nodes, the second group had 1–3 positive lymph nodes, the third group had 4–9 positive lymph nodes, and the fourth group had more than 9 positive lymph nodes. We used ordinal regression to predict the number of involved lymph nodes and binary logistic regression to predict lymph node positivity. We included variables in the regression model with a significance level of 10%. The data analysis was performed using SPSS version 26.0.

Results

Out of 140 cases (Table 1), the majority (80 cases) were in the 41–60 age group, accounting for 57.1%. Nearly two-thirds (91 cases) had tumour sizes ranging from 2 to 4 cm, which is 65% of the total. Additionally, most of the cases (133 out of 140) had a ductular histology. There were a total of 67 patients with pN0, 16 with pN1, 39 with pN2 and 18 with pN3 in the study compared to 42 with cN0 and 98 with cN1. There were no patients with cN2 and cN3 in the study. Fifty-two patients were in Stage III but were in locally operable breast cancer category; hence, we proceeded with MRM. To analyze the data, a bivariate analysis utilizing the Chi-square test was conducted. This analysis revealed a positive correlation between Axillary lymph nodal positivity with the total number of lymph nodes dissected and LVI. It was statistically significant (p < 0.05).

Table 1.

Clinicopathological profile of cases Bivariate analysis

Variables		Lymph nodes positive				Total	p value
		0	1–3	4–9	> 9
Age (n = 140)	21–40	11(39.3)	2(7.1)	10(35.7)	5(17.9)	28(100)	0.591
	41–60	37(46.3)	10(12.5)	22(27.5)	11(13.8)	80(100)
	> 60	19(59.4)	4(12.5)	7(21.9)	2(6.3)	32(100)
Tumour size (n = 140)	< 2 cm	13(56.5)	2(8.7)	7(30.4)	1(4.3)	23(100)	0.771
	2–4 cm	44(48.4)	11(12.1)	23(25.8)	13(14.3)	91(100)
	> 4 cm	10(38.5)	3(11.5)	9(34.6)	4(15.4)	26(100)
Total number of lymph nodes dissected (n = 140)	1–10	-	2(66.7)	1(33.3)	-	3(100)	0.049
	11–20	60(51.3)	13(11.1)	31(26.5)	13(11.1)	117(100)
	21–30	7(36.8)	1(5.3)	6(31.6)	5(26.3)	19(100)
	31–40	-	-	1(100)	-	1(100)
Tumour morphology (n = 140)	Ductal	63(47.4)	16(12)	37(27.8)	17(12.8)	133(100)	0.408
	Lobular	-	-	1(50)	1(50)	2(100)
	Both	4(80)	-	1(20)	-	5(100)
MBR score (n = 125)	3–5	3(37.5)	2(25)	2(25)	1(12.5)	8(100)	0.836
	6–7	24(45.3)	6(11.3)	14(26.4)	9(17)	53(100)
	> 7	32(50)	6(9.4)	19(29.7)	7(10.9)	64(100)
Tumour grade (n = 128)	Grade 1	3(42.9)	2(28.6)	1(14.3)	1(14.3)	7(100)	0.787
	Grade 2	22(45.8)	5(10.4)	13(27.1)	8(16.7)	48(100)
	Grade 3	35(47.9)	8(11)	22(30.1)	8(11)	73(100)
Tumour necrosis (n = 98)	No	24(61.5)	5(12.8)	8(20.5)	2(5.1)	39(100)	0.064
	Yes	21(35.6)	8(13.6)	19(32.2)	11(18.6)	59(100)
LVI (n = 140)	No	34(94.4)	1(2.8)	1(2.8)	-	36(100)	< 0.001
	Yes	32(30.8)	16(15.4)	38(36.5)	18(17.3)	104(100)
Breast cancer subtypes (n = 140)	Luminal A	25(50)	6(12)	13(26)	6(12)	50(100)	0.406
	Luminal B	16(42.1)	8(21.1)	8(21.1)	6(15.8)	38(100)
	Non Luminal HER 2 +	15(45.5)	1(3)	12(36.4)	5(15.2)	33(100)
	Triple negative	11(57.9)	1(5.3)	6(31.6)	1(5.3)	19(100)
Stage (n = 140)	Stage 1	-	10(90.9)	1(9.1)	-	11(100)	0.222
	Stage 2	3(4.2)	61(85.9)	7(9.9)	-	71(100)
	Stage 3	-	45(77.5)	11(19.0)	2(3.5)	58(100)

A Multivariate Logistic (Ordinal) Regression Model was used to predict the number of positive lymph nodes based on independent variables that showed 90% significance in bivariate analysis, such as total number of lymph nodes dissected, tumour necrosis, and (LVI) (Table 2). The statistically significant Chi-square statistic (p < 0.001) indicated that the final model was a significant improvement over the baseline intercept-only model. A Pearson’s Chi-square statistic p-value of 0.953 in the goodness of fit test showed that the fit is good, meaning that the model was fit for the prediction of positive lymph nodes. The Pseudo R2 (Nagelkerke) of 0.496 showed that 49.6% of the variation in positive lymph nodes could be explained by this model. Our findings indicated that patients with positive LVI had higher chances of lymph node involvement than those with negative LVI (OR = 50; 95% CI = 250–9.8). However, the total number of lymph nodes and tumour necrosis did not show significance in predicting the number of positive lymph nodes.

Table 2.

Multivariate logistic regression to predict the number of positive lymph nodes

Variables	Estimate	Odd’s ratio	95% CI	p value
Total number of lymph nodes dissected
1–10	− 1.023	0.359	0.005–23.772	0.632
11–20	− 0.769	0.463	0.011–18.761	0.684
21–30	0.631	1.88	0.043–82.942	0.744
31–40
Tumour necrosis
No	− 0.478	0.62	0.237–1.624	0.331
Yes		1
LVI
No	− 3.889	0.02	0.004–0.102	< 0.001
Yes		1

We used the forward likelihood method of binary logistic regression to predict whether lymph nodes would test positive or negative with LVI, tumour necrosis, and the total number of lymph nodes dissected serving as independent variables. We analyzed the data with a 90% confidence level in bivariate analysis (Table 1). The full model test yielded statistically significant results, indicating that the predictor set could reliably differentiate between positive and negative outcomes (Chi-square: 45.328, p < 0.001, df:1). The overall model was also statistically significant (p-value < 0.05). The model explained between 37.6% (Cox & Snell R Square) and 50.2% (Negelkerke R2) of the variation in the dependent variables. The model’s overall prediction success rate was 81.3%, with a 96.1% success rate for positive outcomes and a 64.4% success rate for negative outcomes. The Wald criterion indicated that only LVI had a significant impact on the prediction (p < 0.05), while tumour necrosis and the total number of lymph nodes dissected were not significant predictors (p > 0.05). Patients with LVI had a 43.47 times higher risk of having positive lymph nodes (p < 0.05) (Table 3).

Table 3.

Binary logistic regression to predict lymph node positivity using forward likelihood method

Variables	Odd’s ratio	95% CI	p value
LVI
No	0.023	0.105–0.005	< 0.001
Yes	1

Discussion

The gold standard of prognostication in breast cancer remains axillary nodal dissection. With the advent of thermalytix screening and increasing prevalence of mammographic screening, more tumours are detected at a smaller size with a lower incidence of axillary nodal metastasis [10, 11]. These patients may not benefit from axillary dissection. They suffer from its complications. This has led to a study of factors predicting axillary nodal metastasis.

Overall, age alone should not be a factor in deciding prognosis. Age may be of greater prognostic significance in patients with luminal cancers than in other subtypes of breast cancer. In a study from the US SEER database (2022), women under 40 years old were more likely to have higher stage, higher grade, HER2-positive and triple-negative subtype disease (all, p < 0.001). Compared to women aged 40–60, women ages < 40 had higher breast cancer mortality in unadjusted analysis. In models controlled for demographic, clinical and treatment factors, young age was significantly associated with an increased risk of breast cancer mortality among women with HR-positive, lower-grade disease but not for women with high-grade/HR-positive, HER2-positive, or triple-negative disease [12]. Similarly, in a study from Texas (2016) of approximately 17,500 women with stage I to III breast cancer, women <  = 40 years of age at diagnosis had increased breast cancer mortality relative to older patients with the most significant increase observed in patients with Luminal A and B cancers. No differences were seen in patients with HER2 subtypes [13]. In our study, age was not associated with the number of positive lymph nodes (bivariate analysis; p: 0.591). The median age for menopause in India is 46 years [13]. Twenty-eight percent (34 out of 140) patients were premenopausal in our study. Astonishingly, it has been shown that among premenopausal patients who received adjuvant chemotherapy, chemotherapy-induced amenorrhoea and lack of resumption of menstrual cycles after chemotherapy is associated with improved survival, after controlling for standard prognostic variables, particularly for hormone receptor-positive disease [14].

The size and stage of a tumour are related to nodal involvement, but their prognostic values are independent. In our study, the correlation between the two factors was not significant (bivariate analysis; p: 0.771 and p: 0.222 respectively). In a meta-analysis of 88 trials involving 62,000 patients with ER-positive breast cancer who were disease-free after 5 years of scheduled endocrine therapy, the risk of distant recurrence was linked to the original tumour size over years 5 to 20. For those without involved lymph nodes, the risk of distant recurrence for T1 versus T2 tumours was 13% and 19%, respectively. Among those with one to three involved nodes, the risks for T1 versus T2 tumours were 20% and 26%, respectively. Among those with four to nine involved nodes, the risks for T1 and T2 tumours were 34% and 41%, respectively. However, in triple-negative tumours, the correlation between tumour size and stage with nodal status and its effect on prognosis has been shown to be much weaker [15, 16].

The minimum number of nodes to be dissected for breast cancer is at least 10 as defined by AJCC 8th edition. In patients with cN0, standard of care is sentinel lymph nodal biopsy undoubtedly. This includes patients with either cN1 or cN0 without facility for sentinel lymph node biopsy and frozen section. In a study from China: 303,760 breast cancer samples were evaluated to compare the number of lymph nodes dissected as a prognostic factor. It was shown that to reduce the possibility of missing positive nodes to less than 10%, 21 lymph nodes should be examined [17]. In another recent study from North Carolina (2020): amongst node-positive breast cancer patients, the number of nodes retrieved is significantly associated with an increased positive nodal count and greater use of adjuvant therapy. Removal of approximately 20 LNs may improve survival by both more accurate nodal staging and increased adjuvant therapy use [18]. In our study, the total number of lymph nodes dissected was shown to be significantly associated with the number of positive lymph nodes (bivariate analysis; p:0.049). But on multivariate analysis, the relation was not significant (p: 0.632–0.744).

The concept of low axillary sampling (LAS) and no axillary surgery (NAS) is a new approach to managing cN0 breast cancer by minimizing surgical complications while maintaining good clinical outcomes [19]. LAS involves removing a limited number of lymph nodes from the axilla less than traditional axillary dissection, aiming to accurately stage the cancer while reducing the risk of complications like lymphadema. Studies like Borkar et al. [20] sampled only four nodes in a study sample of 35 patients, and the result showed comparable result of LAS to sentinel for predicting axillary lymph node status. NAS challenges the standard practice of performing axillary surgery in all cN0 cases [21]. In certain patient groups with low-risk tumour characteristics like tumour < 2 cm with no clinically palpable axillary lymph node, omitting axillary surgery may offer similar cancer outcomes with significantly less risk. Notably, the landmark SOUND trial [22] showed that NAS was as effective as axillary surgery in a select group of patients, sparking interest in its broader application. More randomized studies are needed for these concepts to be put in mainstream treatment protocol.

The most common morphology in breast cancer is invasive ductal carcinoma (IDC) accounting for greater than 70% of all cases [23]. Ninety-five per cent (133/140) of cases in our study were of invasive ductal carcinomas. Tumours with invasive lobular carcinoma (ILC) have a distinctive biology and clinical behaviour compared with IDC, although the prognostic impact of histology appears to vary with time. In a pooled analysis of over 9000 patients with extended follow-up, a 16% lower risk of recurrence for ILC compared with IDC was seen during the first 6 years of follow-up; however, ILC conferred a 54% higher risk of relapse after 6 years [24]. Our study revealed no significant association between morphology and the number of positive lymph nodes (bivariate analysis; p:0.408).

Grading of breast cancer and MBR score have been shown to be prognostic but have no significant association with lymph nodal positivity (p: 0.787 and 0.836 respectively). In a study of 2200 breast patients, a correlation has been shown between histologic grade and worsened outcomes with a hazard ratio for worsened breast cancer-specific survival (BCSS) of 1.6 for grade 2 versus 1 cancer. The hazard ratio was 3.5 for grade 3 versus grade 1 cancers [25].

The tumour necrosis component is not used to define the prognosis for breast cancers in AJCC 8th. However, in our study, it was shown to be significantly associated with the number of positive lymph nodes (bivariate analysis; p:0.064). A study from China in 2023, evaluated 471 patients for prognostic value of tumour necrosis in invasive breast cancer. Tumour necrosis was shown to be an independent prognostic factor for 5-year Disease-free Survival [26]. Therefore, incorporating tumour necrosis into the staging category can help to stratify patients better.

Peritumoral lymphovascular invasion (LVI) was significantly associated with the number of positive lymph nodes in both bivariate and multivariate analysis in our study (p < 0.001). Some studies support this vividly [27] while some do not [28, 29]. An interesting retrospective analysis of 2754 patients treated in two adjuvant therapy trials showed that LVI was associated with worse disease-free survival but its prognostic value was abrogated by adjuvant endocrine therapy. Therefore, LVI has a prognostic value but its clinical utility remains to be determined.

Breast tumours are tested for ER, PR, and HER2 positivity through immunohistochemistry. It has been observed that ER and PR expression are generally linked with better outcomes in breast cancer, at least in the short term. ER is used to determine whether a patient should receive adjuvant endocrine therapy or not. Although the rate of recurrence for ER-positive cancers is typically lower in the first 5 years after initial treatment compared with ER-negative cancers, some studies suggest that it may be higher with longer-term follow-up [30, 31]. To address the long-term recurrence risk of ER-positive cancers, extended endocrine therapy courses are recommended. ER-positive tumours may lead to clinically apparent metastases in bone, soft tissue, or the reproductive/genital tracts. Conversely, ER-negative tumours are more likely to metastasize to the brain and liver, which are associated with shorter survival [32].

Amongst IHC, absent PR expression has been observed to be associated with poorer prognosis for overall survival, breast cancer-specific survival, and disease-free survival, even within the ER-positive, lymph node-negative group and was not influenced by endocrine therapy. These data are supported by the finding that patients with ER-positive, PR-negative disease have a more aggressive subtype of hormone receptor-positive breast cancer [33]. In the absence of systemic therapy, HER2 overexpression has been shown to be a marker of poor prognosis in patients with pathologically node-positive and node-negative breast cancer [34].

Breast cancer subtyping helps to decide the adjuvant therapy for the patient. However, the subtypes were not significantly associated with the number of positive lymph nodes (bivariate analysis; p: 0.406). Luminal A makes up about 40% (35.7% in our study) of all breast cancer subtypes [35]. They have been shown to carry the best prognosis of all breast cancer subtypes [36]. Despite this, most breast cancer deaths are from Luminal A [37]. The less common (27% in our study) luminal B tumours carry a worse prognosis than Luminal A tumours [38]. Most luminal B cancers have high recurrence scores as assessed by the 21 gene recurrence score assay and poor 70 gene prognostic signatures [39]. HER2 enriched formed 23.5% of the study population. In essentially all studies to date of neoadjuvant treatment for HER2-positive breast cancer, pCR rates are higher in HR-negative than in HR-positive cancers. Despite the lower pCR rates, patients with HR-positive/HER2-positive cancers who achieve a pCR still experience improved event-free survival (EFS) relative to those who do not [40]. One hypothesis regarding the lower pCR rates seen in patients with HR-positive/HER2-positive cancers is that binding of estrogen to cytoplasmic estrogen receptors activates signaling pathways that bypass HER2 blockade, which has been referred to as “cross-talk.” For triple-negative tumours (TNBC), the risk of recurrence and death peaks approximately 3 years after diagnosis and declines rapidly thereafter [41]. TNBC is characterized by higher relapse rates during this period compared with ER-positive breast cancers, although the latter tend to continue to recur for decades later while TNBCs tend not to do so. Therefore, overall in the long run, the absolute risk of recurrence for the two subtypes approach one another. Furthermore, however, TNBC may be more likely to recur in locoregional areas as well as in visceral organs, such as liver, lung, and brain involvement at first recurrence [42]. By contrast, TNBC is less likely than ER-positive breast cancer to recur initially in bone. Patients with TNBC have a poorer short-term (first 5 to 7 years) prognosis compared with patients with other breast cancer subtypes [43]. The risk of late recurrence is low for women with TNBC. In a single-centre retrospective series of 783 women with stage I, II, or III TNBC who were alive and without recurrence at 5 years after treatment for the original diagnosis, the yearly recurrence-free interval at 10 and 15 years was 97 and 95%, respectively, and the relapse-free survival rates were 91 and 83%, respectively [44]. Triple-negative tumours formed 13.5% of our study population.

Conclusions

Over the years, the biology of Indian breast cancers has been proven to be different from that of the western world. Most Indian studies report no correlation between Lymph nodal positivity and breast cancer subtypes [8]. This is in contrast with the western studies where breast cancer subtypes are correlated with the number of positive lymph nodes [7, 9]. A key pointer can be derived from this. One is that no matter what IHC reporting says, we have to be vigilant in our lymph nodal dissection in all breast tumour subtypes. Vigilance is the key word here. Our findings reveal that Lymphovascular invasion significantly and independently predicts the number of positive lymph nodes. The use of immunohistochemical staining with a lymph endothelial specific marker such as podoplanin/D2-40 increases the accuracy of identification of patients with tumor-associated LVI [45].

Notably, we observed a significant correlation between higher nodal yield and increased likelihood of nodal metastasis in bivariate analysis but not in multivariate analysis. Thus, emphasizing the importance of sentinel lymph node biopsy in cN0 axilla if facility is available or a complete axillary dissection of minimum 10 nodes.

Limitations

Our study is not without limitations. Further subgroup analysis of clinicopathological factors into various luminal subtypes- and their correlation with lymph nodal positivity would have yielded better results. The impact of multifocal (invasive tumours identified within the same breast quadrant) or multicentric (invasive tumours identified in separate breast quadrants) tumours on lymph node metastasis is controversial with some evidence supporting it [46] while some denying it [47]. The eighth edition TNM staging system does not assign independent value to multifocality and multicentricity. They can be evaluated further as potential factors for prognosis of breast cancer. While lymph node macrometastasis is a well-established independent prognostic factor, the significance of metastatic disease < 2 mm (micrometastases, pN1mic) or isolated tumour cells (ITC, pN0ITC) in axillary nodes is not so clear. Prevailing evidence suggests that patients with pN1mic breast cancer have a worse outcome compared with those with node-negative breast cancer while the presence of isolated tumour cells does not influence prognosis [48, 49]. Both these factors can be evaluated with clinicopathological factors and breast cancer subtypes in future studies. Tumour infiltrating lymphocytes (TIL) density in biopsy specimens of tumours < 2 cm (cT1) is significantly associated with the number of positive lymph nodes [20]. It shows the role of the tumour immune microenvironment playing a role in cancer invasion and metastasis. This can be used to omit/include sentinel lymph node biopsies in small cT1 tumours [50].

Data Availability

Data is available for further analysis. May be requested from the author.

Declarations

Ethics Approval

Obtained from Scientific Committee, SMS Medical College and Attached Group of Hospitals, Jaipur.