The Cochrane Library
Plain language summary
Is a 'quick diagnosis' test on an ovarian mass during surgery accurate?
The issue
When
women go to their doctor with a mass that could be ovarian cancer, they
are normally referred for surgery, since the mass may need to be
removed and examined microscopically in a laboratory in a procedure
known as paraffin section histopathology. A third of women with ovarian
cancer present with a cyst or mass without any visible evidence of
spread elsewhere. However, in these
apparently early-stage cancers
(confined to the ovary) surgical staging is required to decide if
chemotherapy is required. This staging consists of sampling tissues
within the abdomen, including lymph nodes.
Different staging
strategies exist. One is to perform surgical staging for all women who
might have a cancer, to get information about spread. This may result in
complications due to additional surgical procedures that may turn out
to be unnecessary in approximately two thirds of women.
A second
strategy is to perform an operation to remove just the suspicious mass
and await the paraffin section diagnosis.
This may result in needing a
further operation in one third of women if cancer is confirmed, putting
them at increased risks from another operation.
A third strategy
is to send the mass to the laboratory during the operation for a quick
diagnosis, known as 'frozen section'. This helps the surgeon decide if
further surgical treatment is required during a single operation.
Why is this review important?
Frozen
section is not as accurate as the traditional slower paraffin section
examination, and it entails a risk of incorrect diagnosis, meaning that
some women may not have all the samples taken at the initial surgery and
may need to undergo a second operation; and others may undergo
unnecessary surgical sampling.
How was this review conducted?
We
searched all available studies reporting use of frozen section in women
with suspicious ovarian masses. We excluded studies without an English
translation and studies without enough information to allow us to
analyse the data.
What are the findings?
We included 38 studies (11,181 women), reporting three types of diagnoses from the frozen section test.
1. Cancer, which occurred in an average of 29% of women.
2. Borderline tumour, which occurred in 8% of women.
3. Benign mass.
In
a
hypothetical group of
1000 patients where 290 have cancer and 80 have
a borderline tumour, 261 women would receive a
correct diagnosis of a
cancer and
706 women would be correctly diagnosed without a cancer based
on a frozen section result. However,
4 women would be incorrectly
diagnosed as having a cancer where none existed (false positive), and 29
women with cancer would be missed and potentially need further
treatment (false negative).
If surgeons used a frozen section
result of either a cancer or a borderline tumour to diagnose cancer, 280
women would be correctly diagnosed with a cancer and 635 women would be
correctly diagnosed without a cancer. However, 75 women would be
incorrectly diagnosed as having a cancer, and 10 women with cancer would
be missed on the initial test and found to have a cancer after surgery.
If
the frozen section result reported the mass as benign or malignant, the
final diagnosis would remain the same in, on average, 94% and 99% of
the cases, respectively.
In cases where the frozen section
diagnosis was a borderline tumour, there is a chance that the final
diagnosis would turn out to be a cancer in, on average, 21% of women.
What does this mean?
Where
the frozen section diagnosis is a borderline tumour, the diagnosis is
less accurate than for benign or malignant tumours. Surgeons may choose
to perform additional surgery in this group of women at the time of
their initial surgery in order to reduce the need for a second operation
if the final diagnosis turns out to be a cancer, as it would on average
in one out of five of these women.
