Invasive ductal carcinoma (IDC) represents a major percentage of all breast cancer cases affecting women worldwide, accounting for 70–80% of diagnoses annually [1]. The clinical outcome of patients with IDC largely depends on timely diagnosis and early intervention. Fine-needle aspiration cytology (FNAC) is a minimally invasive and inexpensive approach to preoperative evaluation that enables tumor cell grading through cytology [2].  Accurate assessment of tumor grade and staging requires histopathological tissue examination after surgical excision of the tumor. Cytological grading must be accurately related to histopathological grading to increase the reliability of FNAC as a diagnostic and predictive tool that can act as an initial guide for the treatment of tumors [3]. IDC's clinical outcome of IDC also depends mainly on the status of the regional lymph nodes, along with tumor grading evaluation. The presence of cancer cells in axillary lymph nodes defines the staging of the tumor and the chances of patient survival. Some of the common procedures performed for the assessment of lymph node status involve lymph node biopsy (SLNB) and Axillary Lymph Node Dissection (ALND) [4, 5].  Assessment of the relationship between cytological grading, histopathological grading, and lymph node metastasis will help in determining the progression of the disease and could guide surgical treatment and other adjuvant therapies required in these cases. The higher the number of lymph nodes involved, the higher the tumor grade, which requires a more aggressive approach to treatment [3, 6]. Medical decision-making based on disease progression assessment benefits from the knowledge of how cytological grading relates to histopathological grading and lymph node metastasis. Tumors of higher grades tend to spread more actively into the lymph nodes, which indicates an aggressive nature of disease progression.

Several studies have investigated the agreement between cytology and histopathological tissue diagnosis assessments, although the level of agreement was different [7-9]. The findings from research on this relationship show significant variation because of collecting errors human errors in grading procedures, and differences in scoring methods. The use of FNAC as a diagnostic tool requires additional evaluation of population and clinical setting relationships to prove its reliability.  Moreover, assessment of the relationship of the regional lymph node status will reveal the possible behavior of the tumor as well as its metastatic potential. This study aimed to determine the association between IDC grading based on cytology and histopathology. A strong correlation between FNAC and histopathology would increase the reliability of FNAC as a diagnostic tool and possibly prevent expensive investigations. Therefore, we decided to conduct this study in cases reported to our hospital.

This retrospective study was conducted in the Department of Pathology, Mahavir Institute of Medical Sciences, Vikarabad. Telangana. Institutional Ethical approval was obtained for this study. Informed consent was obtained from all participants after explaining the nature of the study in vernacular language.

Forty patients were included in this study. They were diagnosed with infiltrating ductal carcinoma by FNA, and all clinical data regarding the patients were collected. FNA was performed on all cases with a 23-gauge needle attached to a 10 ml syringe with a Franzer-type syringe holder utilizing the multidirectional technique to obtain an adequate specimen. The aspirated material was then transferred onto the slides, smears were prepared, fixed with alcohol, and stained with Hematoxylin & Eosin (H&E) and Papanicolaou (Pap) stain. Air-dried smears were also prepared and stained with May Grunwald Giemsa (MGG) stain. The inclusion criteria for the slides were cases with six or more epithelial cell clusters, which are considered the basic minimum criteria for adequacy. The smears were evaluated based on the grading system described by Robinson's cytological grading of breast carcinomas [10]. Values between 1 and 3 were assigned to each parameter, and scores for each of the six parameters were added to give a total score for each case, where the final score ranged between 6 and 18.

Surgically excised specimens were obtained in each case, and the histological diagnosis of infiltrating ductal carcinoma with cytological diagnosis of infiltrating ductal carcinoma was taken for analysis in the study. The histological specimens were routinely processed according to the standard protocol and stained with hematoxylin and eosin. Axillary lymph node specimens were processed in the same manner. Histological grading of H&E-stained tissue sections was performed using the Nottingham modification of the Scarff-Bloom Richardson method.  Three parameters were taken into consideration: nuclear pleomorphism, number of mitoses, and degree of tubule formation. The mitotic counts were scored using an Olympus microscope with a field diameter of 0.59 mm. Each parameter was scored between one and three. The overall score for each case ranged from 3 to 9.

Statistical analysis: All available data were evaluated, refined, segmented appropriately, uploaded to an MS Excel spreadsheet, and analyzed using SPSS version 22 in Windows format. Continuous variables were represented as means, standard deviations, and percentages, and categorical variables were analyzed using Fisher's exact test. Statistical significance was set at p (<0.05) and was considered significant.

A total of 40 cases were retrieved from the hospital records, included in the study. Table 1 compares Robinson’s Cytological Grading (RCG) with Modified Bloom Richardson Histopathological Grading (MBR) in cases of Infiltrating Ductal Breast Carcinoma cases in the study.

Table 1: Comparison of Robinson’s Cytological Grading RCG) with Modified Bloom Richardson grade

The overall concordance rate between RCG and MBR was found to be 87.5% indicating a strong correlation between cytological and histopathological grading. Grade I: 80.0%, Grade II: 82.5%, Grade III: 100%.  Grade I (RCG vs. MBR): 17 out of 18 (94.4%) Grade I MBR cases were correctly identified by RCG. 3 cases (16.7%) were misclassified as Grade II by RCG. Grade II (RCG vs. MBR): 15 out of 18 (83.3%) Grade II MBR cases were correctly identified by RCG. 1 case (5.6%) was misclassified as Grade I and 2 cases (50%) as Grade III by RCG. Grade III (RCG vs. MBR): 2 out of 4 (50%) Grade III MBR cases were correctly identified by RCG. No misclassifications occurred for Grade III, but the sample size is small (only 4 cases). Most misclassifications occurred between Grade I and Grade II, suggesting overlapping cytological features in these grades. Grade III showed perfect concordance, however since the number of cases was less in the sample.  

Table 2: Sensitivity, specificity, PPV, and NPV for each Robinson's Cytological Grading (RCG).

Table 2 shows the sensitivity, specificity, PPV, and NPV for each Robinson's Cytological Grading (RCG) category. RCG demonstrates high sensitivity for grades I and III, indicating its ability to correctly identify most patients with those respective grades. RCG also shows good specificity in all grades, therefore, it can effectively identify patients who do not have a particular grade. The high PPV values indicate that a positive RCG result is a good indicator of the corresponding MBR grade. In the results, we also found a high NPV value which indicates that a negative RCG result is reliable in ruling out the corresponding MBR grade.

Table 3: Correlation of cytological grade and axillary lymph node status

Table 3 shows the analysis of the cytological grade and axillary lymph node involvement in cases of the study. A critical analysis of the table shows that higher grade 3 tumors were found to have 100% lymph node positivity (2 out of 2 cases), this indicates that high-grade tumors are more likely to metastasize to regional lymph nodes. Whereas the Grade 1 (low-grade) tumors also had a significant proportion of lymph node positivity (53.8%), this indicates that the lower-grade tumors can also metastasize to lymph nodes, although less aggressively than the higher-grade tumors. The results also show that grade 2 tumors have a moderate rate (38.5%) of lymph node positivity indicating their behavior of aggressiveness.

The cytological and histopathological correlation of invasive ductal carcinoma has been a topic of interest for several years. Several reviews in the literature have confirmed the prognostic value of histopathological grading in invasive ductal carcinoma [11, 12]. Fine-needle aspiration samples use various techniques to determine the grade of invasive carcinoma and determine the best treatment option in the given case.  The National Cancer Institute has recommended that tumor grading based on FNA material be incorporated into FNA reports for prognostication. [10] Several studies have developed a variety of grading systems based on cytological examination, and the results were matched with histopathological examination, and the correlation appeared to be good. Among these, the grading system developed by Robinson was highly correlated with the histopathological system of the Scarff-Bloom Richardson method [13-16]. The purpose of cytological prognostic grading is to identify fast-growing tumors (grade III), which are more likely to respond to chemotherapy than low grade.

In the current study, we found a statistically significant correlation between the cases, and the overall concordance rate was 87.5%. Other similar studies with a sample size of less than 70 have reported concordance rates of 63%–89.1% [17, 18] Few studies with several cases more than 70 reported concordance rates as low as 43.3%–90.7% [19]. In the current study, the grading system showed a stronger correlation with higher-grade tumors. Of the cases studied, six cases showed discrepancies, of which five cases were upgraded and one case was downgraded on histopathological findings. This could be due to variability in assigning grades. Nuclear margins and chromatin patterns were some of the features where there might be observer variability. This could be attributable to tumor heterogeneity and large tumor size. Large tumors contain regions with undifferentiated cells that may not receive proper sampling through routine fine-needle aspiration (FNAs). The complete tumor sampling process provided by histopathological examination enables researchers to evaluate the most immature cancer cells. Unique statistical evaluation of cellular characteristics revealed that cell size and cell uniformity with nucleoli appearance represent the dominant influencing elements. Grade I tumors were the most prevalent tumor type in our study, similar to the results of Sultana et al. [13]. The early disease onset is probably because patients in the research area became more vigilant about breast cancer.

Lymph node metastasis is a recognized sign of a poor prognosis in breast carcinoma. The survival rate of patients with lymph node involvement is substantially worse than that observed in nodal metastasis-negative cases [20]. When breast cancer patients show no lymph node involvement, they survive long-term without metastasis at a rate of 70-80% while regional lymph node metastasis gives them a probability of 80% developing distant metastatic disease [21]. Lymph node metastasis was present in 28 of 44 patients (63%) during the evaluation. Eighty-nine percent fifty-two percent and 100% of Grade I and II tumors, respectively, exhibited metastasis. The study revealed that grade III tumors showed increased rates of metastasis, although tumor grade was unrelated to lymph node metastasis statistics.

This study shows that FNAC proves to be a straightforward rapid diagnostic technique suitable for initial breast ductal carcinoma evaluation. Cytological grading according to Robinson proved to be both sensitive and easily duplicateable. The RBS grading system maintains a basic approach. The clinical significance of data collection works alongside prognosis assessment through its combination with mammography. A complete inclusion of cytological grading in FNAC reports for breast cancers will help medical professionals make suitable preoperative therapy choices while preventing unnecessary treatment of low-grade cancers.

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