|Year : 2012 | Volume
| Issue : 1 | Page : 12-16
Does apoptosis contribute to a relatively better prognosis in medullary carcinoma of breast?
M Surekha Venkata, P Uday Kumar
Pathology Division, National Institute of Nutrition (Indian Council of Medical Research), Hyderabad, India
|Date of Web Publication||21-Mar-2012|
P Uday Kumar
Scientist 'E' and HOD, Pathology and Electron Microscopy Division, National Institute of Nutrition (ICMR), Jamai-Osmania PO, Hyderabad - 500 007, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Background and Aims: Apoptosis (programmed cell death) is considered to play a critical role in tumor genesis, where a down regulation of the process contributes to development and progress of neoplasia. Medullary carcinoma (MC) of breast has generally been considered to have a better prognosis than invasive ductal carcinoma not otherwise specified (IDCC-NOS), which would seem to be discrepant when one considers its anaplastic histology and high mitotic rate. We, hence, attempted to elucidate the importance and implications of apoptosis in the prognosis of medullary carcinoma of breast.
Materials and Methods: Formalin-fixed, paraffin-embedded sections of 30 cases of medullary carcinoma of breast and 30 cases of IDCC-NOS (controls) were investigated by light microscopy.
Results: Mean values of apoptotic count was significantly higher in MC than in IDCC-NOS (P< 0.01) while there was no significant difference in the age of patients, size of tumors, histological grade , nuclear grade, mitotic count and Apoptosis/Mitosis ratio (A:M ratio).
Conclusion: It appears that a high frequency of apoptosis may be related to a favorable prognosis in medullary carcinoma even though it demonstrates a high mitotic count with a rapid cell turnover. Since apoptotic cells can be counted with a good reproducibility in H and E stained tumor sections, the apoptotic index could possibly be used as an additional prognostic indicator in invasive breast cancer.
Keywords: Apoptosis, invasive ductal carcinoma-not otherwise specified, medullary carcinoma of breast, mitotic count, prognosis
|How to cite this article:|
Venkata M S, Kumar P U. Does apoptosis contribute to a relatively better prognosis in medullary carcinoma of breast?. J NTR Univ Health Sci 2012;1:12-6
|How to cite this URL:|
Venkata M S, Kumar P U. Does apoptosis contribute to a relatively better prognosis in medullary carcinoma of breast?. J NTR Univ Health Sci [serial online] 2012 [cited 2020 Jul 15];1:12-6. Available from: http://www.jdrntruhs.org/text.asp?2012/1/1/12/94169
| Introduction|| |
Breast cancer is the most commonly diagnosed cancer after non-melanoma skin cancer and is the 2 nd most common cause of cancer mortality after cancer of cervix in women. The lifetime prevalence of this cancer is about 13% in women and it is extremely rare but highly lethal in men. 
Histology, to a large extent, determines prognosis and regards medullary carcinoma (MC) as the carcinoma with a more favorable outlook. Despite the cytological anaplastic features and a high mitotic rate, the prognosis for MC is surprisingly better than for other types of infiltrating ductal carcinomas, with 84% 10-year survival rate, significantly higher compared to non-MC (63%). ,
Several hypotheses were proposed to explain the biological basis for the favorable prognosis of patients with MC, including enhanced tumor cell apoptosis. , Currently, the mainly used characteristics to predict outcome or treatment response in patients with breast cancer is tumor size, Lymph node status, histological grade, and receptor status. The rate of proliferation and apoptosis of cells are assumed to play a key role in tumor progression as well as response to treatment. 
Apoptosis is a biological process by which cells in tissues undergo programmed death, and it is morphologically identifiable and characterized by light and electron microscopy.  It is regulated by a number of key gene products including p53 and bcl-2, which play important roles in this process.
MC exhibits an increased rate of apoptosis and it has been considered to have a better prognosis than invasive ductal carcinoma not otherwise specified (IDCC-NOS), which would seem to be discrepant when one considers its anaplastic histology and a high mitotic rate. The present study, hence, attempted to elucidate the prognostic implications of apoptosis in MC of breast by comparing the apoptotic and mitotic frequencies along with the apoptosis and mitosis ratio (A/M) and expression of p53 and bcl-2 proteins in both MC as well as IDCC-NOS carcinomas in order to determine whether higher apoptotic rates or a greater A/M ratio could be the reason for a favorable prognosis in MC of breast.
| Materials and Methods|| |
A retrospective study was performed on 30 cases of MC of breast and 30 cases of non-medullary IDCC-NOS (controls). Data was retrieved from case notes from the pathology department of National Institute of Nutrition (ICMR), Hyderabad, India.
The biopsy specimens were fixed in 10% neutral buffered formalin and were processed and stained with hematoxylin and eosin stain. Immunohistochemical stains for p53 and bcl-2 proteins were also done, and the intensity of staining was observed in the nuclei and cytoplasm of the tumor cells. The tumors were divided into MC and IDCC-NOS groups based on their histological classification by World Health Organization (WHO), and the histological grading was done by Bloom-Richardson numerical scoring system (Bloom and Richardson, 1957).
Using a microscope ocular grid (100-mm sq. area divided into 100 squares, American optical corp, NY, USA), the number of apoptotic cells and mitotic cells per 10 high-power fields (HPF) was counted. Apoptotic cells were identified as cells having homogenously condensed chromatin with a deeply staining homogenous eosinophilic cytoplasm and a surrounding halo. Only viable areas were chosen; necrotic areas avoided and only unequivocal mitotic and apoptotic cells were considered.
The tumors were graded into grades I, II, and III, based on their mitotic counts, degree of tubular differentiation, and nuclear grade. Lymph node status was also graded as 1-3 based on the number of nodes being positive for tumor cells (I - No positive nodes, II - up to 3 positive nodes, and III - more than 3 positive nodes). 
Mitoses, both normal and abnormal, were taken into account, number of apoptotic and mitotic cells per 10 HPF were counted, and the A/M ratio was calculated. 
Both, the parametric (Student 't' test) and non-parametric (Mann-Whitney), statistical analyses of the results obtained were done to look for any significant difference.
| Results|| |
The [Table 1] shows the results of our study. The mean age of the patients with IDCC-NOS was 55.5 years while it was 50.6 years in the patients with MC. The tumors were bigger in size in MC with the mean size being 4.6 cm and 4.0 cm in IDCC-NOS. The histological grading of the tumors showed the mean grade of IDCC-NOS as 2.07 and of MC as 2.26. Similarly, a higher mean nuclear grade of 2.08 was observed in MC and a lower grade of 1.65 was seen in IDCC-NOS. MC showed a higher mean apoptotic count of 39.5 while that IDCC-NOS was significantly lower, which was 23.14. Similarly, a higher mean mitotic count of 21.0 was encountered in MC while the IDCC-NOS showed a lower mitotic count of 18.07. A/M ratio was also high in MC (2.76) while it was lower in IDCC-NOS (2.55). The average number of cells positive for p53 was 16.75/HPF in IDCC-NOS and was 18.05/HPF in MC, which, however, was not statistically significant.
| Discussion|| |
Breast cancer is by far the most frequent cancer of women (23% of all cancers), with an estimated 1.15 million new cases in 2002, ranking second overall when both sexes are considered together.  Also, the incidence rating of breast carcinoma is increasing in most countries.
The age of onset of cancer in our study was in line with previously published literature.  The average size of IDCC-NOS tumors in our study was 4.0 cm while that of MC was 4.6 cm, which was, however, not statistically significant. The mean age of patients with IDCC (NOS) was more (6 th decade) while that of patients with MC was 5 th decade, thus indicating that MC, comparatively, is a tumor of younger women.
Microscopically, the tumour cells in IDCC-NOS grow in diffuse sheets, nests, cords, or individual cells, and the cells also vary in size and shape [Figure 1].
|Figure 1: Microphotograph of invasive ductal carcinoma not otherwise specified showing an apoptotic body and an abnormal mitosis. (H and E, ×40)|
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MCs on the other hand have diffuse growth with minimal or no glandular differentiation. The tumor cells are large and pleomorphic, with large nuclei, prominent nucleoli, and numerous mitoses. A constant microscopic component is a prominent lympho-plasmacytic infiltrate at the periphery of the tumor [Figure 2].  In our study, histological grading, however, did not show any significant difference between both the tumor types studied. The average nuclear grade of IDCC-NOS in our study was, however, less than that of MC, thus proving that cells of MC were more pleomorphic than those of IDCC-NOS.
|Figure 2: Microphotograph of medullary carcinoma showing one apoptotic body and one mitotic figure. (H and E, ×40)|
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Despite the cytological anaplastic features and a high mitotic rate, the prognosis for MC is surprisingly better than for other types of infiltrating ductal carcinomas with an 84% 10-year survival rate, which is significantly higher than for patients with non-MC (63%). , Several hypotheses were proposed to explain the biological basis for the favorable prognosis of patients with MC, including enhanced tumor cell apoptosis. , Hence, we in our study studied the apoptotic rates and mitotic rates in both IDCC-NOS and MC, and attempted to elucidate the prognostic implications of apoptosis in MC breast.
Although it is accepted that electron microscopy is the best way to identify apoptotic cells,  this method is not practical enough to be followed in most centers. Counting of apoptotic bodies using light microscopy is feasible, and the technique has been used and described in many studies. [Figure 1] and [Figure 2] show the apoptotic bodies in both the types of breast carcinomas.
Tumor growth is a summation of mitosis and cell production and cell loss and death. Thus, tumors, which exhibit more apoptosis may be slower growing and therefore less aggressive. In our study too, we encountered a significant difference (P<0.01) in the apoptotic counts of both tumors. The apoptotic counts were significantly higher in MC when compared to IDCC-NOS. However, no significant difference could be observed in the mitotic counts of both the tumors. [Figure 1] and [Figure 2] demonstrate the mitotic Figures in the IDCC-NOS and MCs. Thus, in our study, we have demonstrated that although MC exhibits high mitotic counts at par with mitotic counts of IDCC-NOS, it definitely showed higher apoptotic counts than IDCC-NOS. Hence, we can say that increased apoptosis balancing increased cell proliferation might be a possible explanation for the more favorable prognosis in typical MC.
Apoptosis is regulated by a number of gene products including p53, bcl-2, and c-myc, which play important roles in this process. P53 monitors the cell's DNA and induces the cell to undergo apoptosis. Mutation of p53 gene commonly occurs in cancers.  Bcl-2 family of proteins in turn promotes cell survival by inhibiting apoptosis. The expression of bcl-2 and p53 as regulators of apoptosis was immuno-histochemically analyzed in our study. P53-positive cells exhibited intense nuclear stain in both the tumor types [Figure 3] while none of the tumors showed positive staining for bcl-2 [Figure 4]. Invasive breast cancer has reduced bcl-2 immunostaining when compared with normal breast epithelium and pre-invasive breast lesions.  Thus, this could explain the absence of staining observed in both IDCC-NOS and MC cases in our study, as both are invasive lesions. Although, p53 being pro-apoptotic and apoptosis being relatively high in MC, the mean number of p53-positive cells in MC and IDCC-NOS, observed in our study, were statistically insignificant. This could probably be due to less number of cases taken for p53 immunostaining.
|Figure 3: Microphotograph showing cells with strong positive nuclear immunostain for p53-immunohistochemistry, ×40|
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|Figure 4: Microphotograph showing cells with negative staining for bcl-2-immunohistochemistry, ×20|
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| Conclusion|| |
Apoptotic cells can be readily and accurately counted with good reproducibility in hematoxylin and eosin stained tumor sections, and apoptotic index hence may be used as an additional prognostic indicator in invasive breast cancer.
The present data in our study indicates that apoptosis is definitely higher in MC than IDCC-NOS. Hence, increased apoptosis seems to be balancing the increased cell proliferation common to all malignancies and hence might explain the more favorable prognosis in MC of breast, as tumor growth is a summation of mitosis and cell production and cell loss and death.
Insignificant difference in the p53 and bcl-2 expression in our study, however, suggests that apoptosis, rather than proliferation index or expression of p53 and bcl-2 protein, may be an independent factor for prognosis in MC.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]