METHODS
This study was a case series, and 10 dogs confirmed for IMC diagnosis were included. Their clinical and
pathological parameters and recurrence findings and Disease-Free Survival Rate (DFS) were calculated,
and paraffinic blocks were stained by ER, PR, HER2, Ki67, TP53 and COX2 markers and their relationships
with DFS was obtained.
RESULTS
In 40% of cases the lymph nodes were involved. All tumors were high-grade and had 70% of vascular
invasion and dirty margins. Evaluation with IHC showed only 10% of them were hormone receptor positive
and 70% were HER2 positive. Ki67 was high in all patients and HER2 and triple negatives molecular
subtypes accounted for 70% and 30% of cases, respectively. 80% of cases were p53, and the COX2 enzyme
was positive in all cancers. Statistical analysis showed that DFS was associated with Ki67 expression and the
risk of recurrence increased with the elevation of its expression.
CONCLUSION
In dogs, IMC mimics many of the clinical, pathological, and molecular characteristics of human IBC,
and is likely to be a suitable model for comparative oncology studies.
Keywords: COX2 enzyme; disease-free survival; inflammatory breast carcinoma; inflammatory mammary carcinoma; molecular subtype
Surgical treatments are not very successful, and the
risk of local recurrence and metastasis is high.[
Despite the complexity of the diagnosis and treatment
of IBC, research in this area also presents challenges.
Mouse models can never exhibit the clinicopathologic
features of IBC. Although the IBC xenograft
tumor models (cell lines isolated from pleural effusion
of IBC) are biologically capable of mimicking the characteristics
of human disease, they lack some of the
pathological features such as dermal lymphatic invasion.[
In recent years, canine mammary cancer (CMC) has
been the focal point of cancer research, because CMC
has many biological, pathological and behavioral parallels
with human breast cancer (HBC).[
One of the weaknesses of pet oncology studies is
the challenge in assessing overall survival rate (OS)
and disease-free survival (DFS) for the reason that follow-
upped patients have many problems after diagnosis
until relapse or death. In this case series study, we
attempted to record patients accurately, and to obtain
DFS, by precisely recording the information regarding
clinical, surgical, and IMC pathology of the dogs. We
then determined the molecular subtype of IMC and
evaluated the diagnostic biomarkers of tumor proliferation
status, p53 status, and COX2 enzyme expression
in the cancerous tissue in order to compare the similarities
and differences with IBC.
a. Patients" clinical records: The following parameters were determined: Patient records, the age, breast number involved, tumor laterality, tumor size (present in patient"s clinical record or report), the status of axillary or inguinal lymph nodes (according to cytological or histopathologic information), postoperative complications, symptoms of clinical recurrence of cancer, DFS (Time from surgery to cancer recurrence), and the fate of the patient after recurrence was determined.
b. Pathology report: In the pathology reports of the
patients, the following were stated: tumor histology
(based on Goldschmidt classification),[
c. Study by Immunohistochemistry (IHC): Patients"
slides were reviewed and an appropriate paraffin
block was selected from each patient's tumor, and
six 3-micron slides were prepared for IHC. After
deparaffinization of the slides and tissue rehydration,
the retrieval antigen stage was performed
with a microwave. Neutral peroxidases were neutralized with oxygenated water, and after washing
in buffered solutions, the primary antibodies (according
to Table
d. Statistical analysis: Significance level was set at 0.05.
To assess the correlation between Ki-67 expression
and DFS, we used linear regression analysis. DFS
curves between different groups were assessed by
log-rank (Mantel-Cox) test. All analyses were performed
by Graphpad Prism 6.0.
1. Description of Clinical Condition: Dogs were ranging
from 4 to 12 years old with a mean of 8.1±2.4 years.
For finding clinicopathologic relationships, they were
divided into two groups of <8 years (younger cases)
and >8 years (older cases). 50% of cases were 4-8,
and the other 50% were 8-12 years (Table
2. Description of histopathologic condition: Results
of the study demonstrated that the tumor histology of
tubulopapillary carcinoma had the highest frequency;
tubular carcinoma and comedo type carcinoma were
placed in the next categories. From the grading system
point of view, 60% of tumors were in grade III
and the rest of them were in grade II. No tumor was
classified as grade I (Table
a. Description of the situation of IHC: Evaluation and
reporting of ER & PR: The interpretation method
was accomplished using All-Red Scoring System.
Immunoreactivity above 1% of malignant foci was
taken as positive cases. Our study showed that progesterone
receptors were absent in all 10 tumors,
and tumor growth was estrogen-receptor dependent
only in 1 patient (Table
b. Evaluation of HER2: In this research work, 70%
of patients showed an over-expression of HER2
protein and the microscopic pattern +3, whereas
30% of them demonstrated negative and equivocal
scores (Table
c. Evaluation of Ki67: Based on the findings of the
present study, the proliferation coefficient ranged
between 15-35%, and, according to the St. Gallen
Guideline (2011), all mammary gland tumors were in the situation of a highly proliferation index
(Table
d. Evaluation of molecular subtype: In this study, 60%
of patients were categorized in the HER2 group and
30% in the triple-negative subgroup. Only one patient
was in luminal B molecular group while no
one was in Lumina A (Table
e. Evaluation of TP53 gene: In this study, 80% of patients
were recognized as IHC positive and 2 patients
were reported as negative (Table
f. Evaluation of COX2 enzyme: The results of this study
showed that the expression of COX2 enzyme was
strong in 80% of IMCs and intermediately positive
in the remaining 20%. Neither negative nor weakly
positive case was found among the patients (Table
4-Description of post-operative complications, recurrence
of clinical findings & metastasis, DFS rate
and patient outcome: The results of post-operative
follow-up showed that surgical complications were observed
in 50% of cases (n=5), so that the main problems
after surgery were related to the opening of sutures
and inflammation of the urethra. In one case,
infectious and secretory lesions in the surgical area
were reported (Table
5- Data Presentation and Statistical Analysis: Regression
analysis showed that there was an inverse relationship
between Ki67 and DFS values, which was statistically
significant (p=0.0129; R2=0.5591 (In other words,
with the increase of tumor proliferation coefficient, the
time of tumor recurrence had decreased (Fig.
DFS: Disease-free survival.
COX2: Cyclooxygenase 2, DFS: Disease-free survival.
Veterinarians reported a disease in dogs similar to
that of IBC in women, and epidemiological and molecular
evidence suggests that IMC may be similar with
human IBC.[
In terms of laterality, the tumors on the left side
were slightly larger than on the right. This is also mentioned
in breast cancer in women, but its biological
causes have not yet been elucidated.[
Microscopic studies showed that more than 90%
of IMC tumors were tubular and tubulo-papillary carcinomas
and were in grade II-III. Our findings were
consistent with many studies on dogs and women, i.e.,
in most cases the tumor grade is high at the time of diagnosis.[
An IHC study showed that 90% of the tumors studied
lacked hormonal receptors (90% had a negative
ER and 100% had a negative PR). On the other hand,
HER2 was reported to be 70% positive. Scientific evidence
suggests that the lack of hormonal receptors and
positive HER2 increase the invasive potency of breast
cancer.[
A study with Ki67 showed that 100% of the tumors
were highly proliferated, and this alone indicates that
the IMC was aggressive. Ning and colleagues studied
257 women with stage III IBC and concluded that the
average Ki67 was higher than 48% and had a significant
relationship with the reduction of overall survival.[
From a molecular subtype point of view, more than
90% of tumors were in the HER2 and triple-negative
categories. Most studies in women show that most
inflammatory breast cancers fall into these two categories.[
p53, also known as the TP53 gene, was positive in
80% of the cases in this study. This biomarker is one
of the most important control genes in the cell cycle;
its wrong over-expression causes the loss of function of
the control factor in the cell cycle. As a result, the prognosis
of the patient becomes weaker.[
COX2 enzyme, which is an inducible enzyme in
cases of inflammation and tissue irritation, acts as
a cancer-promoting agent in tumors. Most of the effects
of this enzyme are attributed to prostaglandin
E2 (PGE2).[
The statistical results of this study showed that there
was no significant correlation between the expression
of COX2++ and COX2+++ with DFS, although according
to Figure 3, there is a tendency between COX2 and
DFS enzyme expression. It is possible that if the sample
size of the study was large, there would be a significant
correlation. Lack of expression of COX2 enzyme in our
studied tumors indicates the possible role of COX2
selective inhibitors in disease control or survival improvement.
In this regard, it is suggested that further
studies should be conducted about this subject in the
field of comparative oncology.
The limitations of this study were the low sample
size and lack of access to patients" overall survival rates.
In pet oncology, measuring the overall survival rate
cannot be accurate as the animals are euthanized at the
end-stage due to moral considerations. The DFS is said to be a possible surrogate for the overall survival rate in
estimating survival rates.[
Over time, the value of comparative oncology increases
and the influence of the science pet oncology
over human oncology becomes more prominent every
day. Previous studies have shown the similarities between
IBC in women and IMC in female dogs. In this
study, we studied the clinical, pathological, and immunohistochemical
aspects of IMC dogs and followed
them and obtained their DFS. Our results showed that
canine IMC is similar to women"s IBC in many biological
and clinical aspects. However, molecular studies are
not yet sufficient in the field of dogs" IMC.
It is suggested that, by initiating clinical trials, the
therapeutic value of COX2 enzyme inhibition and other
genes involved in the molecular pathway, the production
of this inflammatory mediator in IMC should be
studied. This would be an important step taken toward
comparative oncology goals. Multidisciplinary team
studies between various animal oncology specialists
and intra-disciplinary medical oncology teams will
improve the treatment of pet animal cancers and the
results may be extended to human cancer.
Acknowledgement: The authors express their gratitude to
Dr. Ahad Muhammadnajad, a pathologist at the Cancer Research
Center of Tehran University of Medical Sciences, who
has helped with all stages of the study.
Peer-review: Externally peer-reviewed.
Conflict of Interest: All authors declared no conflict of interest.
Ethics Committee Approval: The ethical committee approval
was received from the Ethics Committee of Islamic
Azad University - Science & Research Branch (Tehran, Iran)
with the protocol number of 930139779 and the decision
number of IR.IAU.SRB.REC.1398.180.
Financial Support: The project was financed by Sanaz Rismanchi,
as a self-financing PhD student.
Authorship contributions: Concept - P.M., S.R.; Design
- S.M., S.R.; Supervision - P.M.; Funding - S.R.; Materials -
S.R.; Data collection and/or processing - S.R.; Data analysis
and/or interpretation - S.M.; Literature search - S.R.; Writing
- S.R.; Critical review - P.M.