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2019, Volume 35, Number 1, Page(s) 046-051
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DOI: 10.5146/tjpath.2018.01439 |
Frozen Section Evaluation in Head and Neck Oncosurgery: An Initial Experience in a Tertiary Cancer Center |
Sangeetha K NAYANAR1, Aswathi KRISHNAN M1, Mrudula K I2, Sajith Babu THAVAROOL P3, Shivakumar THIAGARAJAN4 |
1Department of Clinical Laboratory Services and Translational Research, Malabar Cancer Centre, THALASSERY, KERALA, INDIA
2Department of Oral Pathology, Kannur Dental College, ANJARAKANDY, KERALA, INDIA
3Department of Surgical Oncology, Malabar Cancer Centre, THALASSERY, KERALA, INDIA
4Department of Head and Neck Surgical Oncology, Tata Memorial Centre, MUMBAI, INDIA |
Keywords: Frozen sections, Margins of excision, Head and neck neoplasms |
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Objective: Frozen section evaluation is routinely used by oncosurgeons across specialties for rapid assessment of the presence of tumor in any
tissue and its most common use is in surgical margins. Today, the use of intraoperative frozen-section evaluation of surgical margins is an
accepted and frequent practice in head and neck oncology. This study aims to determine the efficacy and accuracy of frozen sections in head and
neck cancer patients and compare the results with the respective paraffin sections and also to analyze the reasons for any disparity between them.
Material and Method: A retrospective study was conducted to evaluate efficacy and accuracy of frozen section in head and neck cancer of 265
patients, treated at a tertiary cancer centre hospital between January 2013 to December 2014.
Results: Out of 265 cases, it was found that 12.6% of these sections showed true positivity, 6.3% false positivity, 2.9% false negativity and 78.2%
true negativity. The study also shows a sensitivity of 82.05% and specificity of 96.46%.
Conclusion: Our study shows that intraoperative frozen section reports are specific and highly sensitive. We recommend a minimum of 3-4
sections, optimum cryostat temperature, good section thickness and quality staining for a good concordance rate. |
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Frozen section evaluation is a key technique used by
pathologists during the intraoperative consultation 1.
It plays an important role in the surgical management
of patients with neoplastic disease and is an essential
component for a surgical theatre complex. The modern
frozen section as practiced today was developed by Dr.
Louis B Wilson in 1905 2. After the introduction of the
cryostat in 1960, frozen section became a highly accurate
procedure for assessing margin status intraoperatively
3. It is routinely used by surgeons across specialties for
rapid assessment of presence of tumor in tissues, the most
common being the surgical margins.
During oncosurgery, it is important for the surgeon to
know if the surgical margin is clear of malignant cells 2,4,5. The report given is usually binary in nature and it just
indicates the presence or absence of tumor in the sample.
Based on this report, the surgeon makes a decision on
whether to make additional resections or not.
The use of intraoperative frozen section evaluation of
surgical margins is an accepted and frequent practice in
head and neck oncosurgery 6. Frozen section analysis is a
multistep process, beginning with retrieval of the specimen
from the patient by the surgeon followed by preparation of
slides, their microscopic examination and possible specimen
triage for further workup, and finally rendering the frozen
section (FS) diagnosis. The frozen section diagnosis is
usually communicated verbally to the surgeon by the
pathologist via telephone, intercom, video conference 7,
and sometimes in person via an intermediary (e.g., nurse
or other OT personnel). Such reports enable the surgeon
to decide on whether further resections are needed or not. |
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Abstract
Introduction
Methods
Results
Disscussion
References
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A retrospective study was conducted to evaluate efficacy
and accuracy of a frozen section in head and neck cancer
involving 265 patients after obtaining informed consent
from the participants and the institutional review board
of Malabar Cancer Centre. Data was collected from the records of frozen section reports of head and neck cancer
patients, MCC, during the period from 2013 January to
2014 December. All head and neck tumor resections which
had intraoperative consultations involving frozen sections
were considered. Patients with biopsy-proven head and
neck carcinoma of all age groups with no sex predilection
were included in the study. During the procedure the
cryostat temperature was kept at -22°C and sections were
cut at 6 microns thickness with 2-3 sections per each block.
The apparatus used was Leica CM 1850 UV. Details of
the frozen section reports were collected along with age,
gender and diagnosis. Frozen section reports were analyzed
for tumor, surgical margins and lymph node metastasis.
For all cases reported as positive margin, re-resections
were done and all specimens were sent for routine margin
analysis. Permanent section diagnosis is widely considered
to be the datum in this diagnosis area 5. Reports were
cross checked with the corresponding paraffin sections and
analyzed for any mismatches. No patients received neoadjuvant
chemotherapy prior to surgery.
Cases sent to our department for frozen section evaluation
included those cases for primary diagnosis as well as
cases for margin status and/or lymphnode metastasis. A
total of 265 patients were selected and 734 sections were
analyzed. After taking tissue bits for frozen sections, the
remaining tissue was used for formalin fixation and for
taking permanent sections. Frozen sections are critical to
immediate surgical management 6,8. Studies have also
shown that survival rates are decreased if resection margin
is found to be positive 4,9. A routine review of frozen
section can improve the accuracy of the procedure 5,8.
Primary objective:
• Baseline the error rates of frozen section in our
institution
Secondary objective:
• Recognize factors affecting the error rates
• Discuss improvements for the common factors causing
the error
Statistical analysis was performed on the collected data
using the statistical software SPSS. Crosstab analysis was
used to find the sensitivity and specificity values. LR+ and
LR- values were derived from sensitivity and specificity.
The confidence intervals were obtained using the ROC
curve analysis in MedCalc software, version 18 (MedCalc
Software, Acacialaan 22, Belgium, https://www.medcalc.
org/). ROC curve analysis figures were cross verified using
the diagnostics test evaluation tool of MedCalc. |
Top
Abstract
Introduction
Methods
Results
Disscussion
References
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A total of 265 patients were selected and 734 sections were
analyzed. The patient demographic data is summarized in
Table I. Margin analysis was done for 195 cases, 41 cases
were analysed for lymph node metastasis, and 45 cases
were sent for primary tumor analysis. There are overlaps
and each test was carried out on a need basis. The majority
of the cases were squamous cell carcinoma (Figure 1A,B-
2A,B). Other carcinomas like malignant tumors of thyroid
carcinomas (Figure 3A,B) were also observed. There were
15 cases which showed disparity out of which seven cases
were reported as false negative and eight cases were reported
as false positive. The overall statistics are summarized in
Table II.
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Figure 1: A) Frozen section of squamous cell carcinoma (H&E; x100). B) Permanent section of squamous cell carcinoma (H&E; x100). |
Click Here to Zoom |
Figure 2: A) Frozen section of lymph node metastasis of squamous cell carcinoma (H&E; x100). B) Permanent section of lymph node
metastasis of squamous cell carcinoma (H&E; x100). |
Click Here to Zoom |
Figure 3: A) Frozen section of lymph node metastasis of thyroid papillary cell carcinoma (H&E; x40). B) Permanent section of lymph
node metastasis of thyroid papillary cell carcinoma (H&E; x40). |
The prominent sites affected were the tongue and buccal
mucosa. Table III has the details of the sites. Comparison
of frozen section results with the permanent sections are
shown in Table IV.
Click Here to Zoom |
Table IV: Comparison of frozen section results with the permanent sections. |
Table V shows observed values and interval estimate for
sensitivity, specificity, disease prevalence and likelihood
ratios along with 95% confidence interval for these values.
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Top
Abstract
Introduction
Methods
Results
Disscussion
References
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Frozen section analysis during intraoperative consultation
is important in ensuring adequate margin clearance 5,10,11. Margin clearance is essential in head and neck
oncosurgeries 4,12 as it reduces the recurrence. During
intraoperative consultations, the patient will still be under
anesthesia and the average time taken for frozen section is
about 20 minutes 8,13 when done by only one seasoned
pathologist.
There were total of 15 discordant cases. However, only
one of these discordant cases had an impact on immediate
clinical management. We also observed that there was no
discordance in the cases where a lymph node analysis was
done. A study by White and Trotter 14 has shown very low
rates for discordances in case of lymph node metastases (4
out of 427 cases), which matches our experience. Similarly,
a study by Hatami et al. mentions only one discordant case out of 23 lymph nodes analysed 5. However, there
are many other studies where discordance/deferral rates
involving lymph node frozen sections are high 6,8.
Analyzing the reasons for the disparity, it was noted that an
inadequate number of deeper sections lead to false negativity
in two cases of invasive carcinoma. Many studies have also pointed out similar reasons for false negatives 6,8,10,15.
Technical pitfalls such as thickness of the frozen section
and folding were the reasons that lead to false negativity in
the remaining five cases. Issues in staining by rapid H & E
methods (e.g. cases of normal epithelium misinterpreted as
mild/moderate dysplasia) lead to false positive cases. The
details of the discordant cases are described below.
Only two out of 265 cases (one carcinoma of the buccal
mucosa and the other carcinoma of the tongue) showed
disparity due to lack of deeper sections. These formed
0.75% of the cases. Hence, it might not be wiser to conduct
an increased number of deeper section analysis and expect
the overall disparity figures to reduce significantly. The
time and human resource factors for doing so should also
be factored in here. The researchers who have studied
this particular aspect are of the opinion that the cost
implications can be argued in either direction 10. Results
of other studies have also shown very low rate of disparity
due to lack of deeper sections when compared with the
overall cases 6,10,15. In our opinion, considering the
time and cost factor, a lower priority can be assigned to this
factor.
All other false negative cases (1.88% of the cases) were
either due to staining issues, section folding, thick sections
and/or lack pathologist’s experience which contributed
to misinterpretation of the sections. Studies have shown
that frozen section is important and highly effective in
avoiding re-operations 16,17. In sites such as head and
neck, margin clearance is crucial as recurrence can be
very aggressive and difficult to treat 18. Hence, a false
negative is more costly during intraoperative frozen section
analysis as it will lead to recurrences and repeat surgeries in
future. So, the issues that are main causes of false negatives
should be addressed with more rigour. All these issues can
be rectified with proper training of the technicians and
pathologists involved in the frozen section evaluation.
On the other hand, all false positives (2.6% of the total cases
and 46.67% of the cases showing disparity) occurred from
the issues with staining. It is important to avoid such issues
from the view point of improving the accuracy of frozen
sections. Caution should be exercised in maintaining a
clean stain line with regular solution changes, following
recommended timings, etc.
The true positive rate also deserves a discussion as this
rate is 12.07%. This indicates that a considerable number
of patients benefited from the use of frozen section and it
underscores the importance of frozen sections in head and
neck oncosurgery.
Looking at the statistical figures, the sensitivity (82.05%)
and specificity (96.46%) values closely match a similar-sized
study by Du E et al. 19. Our specificity value also matches
approximately with the values found in other studies 5,11,20. As can be seen from the likelihood ratio analysis,
frozen section indicates a high increase in the likelihood of
the disease (LR+ > 10). Also, the LR- value is 0.19, which is above 0.1 but below 0.2. This indicates that frozen sections
have been moderately effective in indicating reduction in
the likelihood of the disease though the negative results
cannot be considered to be conclusive 21. The above
values come close to the values found in the study by
Carvalho et al. 22. However, to avoid repeat surgery, it
is desirable that the negative results be more conclusive.
This aspect should be improved in our particular setup.
Currently, false negatives due to technical faults contribute
71% of the total false negative cases. If we can reduce the
technical errors by 50%, it can be shown that LR- figure can
be improved to 0.12. This will be a very good improvement
over the present condition. It should be kept in mind that
samples were all intraoperative and it might not be correct
to generalize the above statement beyond such cases.
Our overall accuracy rate was 94.4% (5.6% discordance).
Other studies have shown the accuracy rate of head and
neck frozen sections to be in the range of 96% to 98% 6,10. Intraoperative Consultation in Surgical Pathology
23, published by Cambridge University press in 2010, has
put the error rates at < 2% after consolidating results from
about six relevant studies. Our accuracy rate is slightly
below, but not grossly off the mark.
In conclusion, the present study shows frozen section
reports are reasonably accurate and essential in the head
and neck oncosurgery. The operating surgeon should also
be aware of the limitations of frozen section 5,24. We
recommend a minimum of 3-4 sections, optimum cryostat
temperature, good section thickness and quality staining
for a good concordance rate. The analysis and discussion
presented above is mainly from the perspective of a tertiary
cancer center with resource constraints that has just started
frozen section analysis and we believe such analysis can
be useful for centers similar to ours. As observed in other
studies 6,8,25, we have also experienced that periodic
review of the correlation between frozen section diagnosis
and permanent section diagnosis is needed for better service
quality and we strongly suggest that centers, and especially
those at the starting stage, follow such review process.
CONFLICT of INTEREST
The authors declare no conflict of interest. The study is not
sponsored by any institution. |
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Abstract
Introduction
Methods
Results
Discussion
References
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Top
Abstract
Introduction
Methods
Results
Discussion
References
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