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Diagnosis
How is advanced laryngeal cancer diagnosed?
A physician specializing in throat disorders (otolaryngologist) can diagnose a tumor in the larynx.
Step 1: History and Physical Exam
The first step is to obtain a thorough history of the patient's
symptoms and perform a complete, careful physical examination (table
exam, anatomy diagram) of the patient's head and neck.
Step 2: Examination of the Voice Box
The voice box or larynx must be evaluated thoroughly. This
evaluation can be done either with a mirror or with a thin flexible
lighted fiberoptic scope that passes through the nose or the mouth into
the back of the throat, allowing the physician to look down the throat
into the larynx and entrance into the swallowing passage. There are
also rigid, non-flexible telescopes that some physicians use for the
same purpose. Although this examination may cause some anxiety on the
part of the patient, it is actually well tolerated and usually does not
cause much more than minimal discomfort for a very brief period of
time. The examination using a scope is called laryngoscopy. (For more information, see Laryngoscopy/Stroboscopy.)
Step 3: Pathological Analysis of Tumor Tissue
If laryngoscopy detects a mass that may be cancerous, a biopsy will be performed. A biopsy involves a very fine needle inserted into
the mass, usually without any significant discomfort, to obtain cells
for analysis. These cells are analyzed under a microscope by a
specialized physician (pathologist).
In some cases of advanced laryngeal cancer, an individual may have a
tumor that has spread to the lymph nodes in the neck, causing a mass or
swelling of the neck. A biopsy of the neck mass can usually be done
without significant discomfort. If this mass has tumor cells, the
physician can usually advise the patient if the cells most likely came
from a primary tumor in the larynx. Treatment discussions can then
begin without a trip to the operating room for a biopsy of the primary
tumor in the larynx.
Step 4: Microlaryngoscopy
If the physician observes something suspicious upon examination, a
better look at the mass will be necessary. The larynx can be examined
with specialized instruments in the operating room, with the patient
under anesthesia. While the patient is asleep, the physician can get a
good look at the throat and biopsy any area that looks suspicious for
cancer (abnormal size, shape, surface, etc.). This process is a usually
referred to as direct laryngoscopy.
Direct laryngoscopy is done in the operating room for two reasons:
- A patient not under anesthesia will exhibit the gag
reflex, preventing the physician from getting a good look at the mass
or touching it with instruments. Direct laryngoscopy allows the region
to be examined in great detail. Soft tissue can be moved with
instruments for better visualization.
- During a direct
laryngoscopy, a biopsy of the lesion can be taken. This will give the
physician a better idea of the extent of the tumor and its involvement
with surrounding structures in the larynx.
After direct laryngoscopy, the patient usually goes home the same
day without much discomfort. The pathology reports from the biopsies
often take four to five days for processing. The report is given to the
physician for discussion with the patient.
 Key Information
Pathology Analysis of Specimen Key to Cancer Diagnosis
The main way that cancer is diagnosed is through pathology analysis of a biopsy specimen or the excised tumor itself. Briefly, pathology
analysis involves the highly magnified study of the tissues under a
microscope. Pathology analysis determines whether cancer cells (which
look different than normal cells) are present.
While
clinical examination and scans are important in determining the extent
of a tumor, the actual diagnosis can only be made when a biopsy is
taken from a suspicious area and examined by a pathologist.
- A pathologist can give the surgeon an approximate diagnosis within an hour of a biopsy submission, using a technique called "frozen section analysis."
However, a more reliable pathologic diagnosis takes longer – about four
to six days – because of the necessary preperation time of biopsy
section slides for the pathologist to examine.
Because of Technique limitations, tumor stage is upgraded (upstaging) after pathology analysis in 20 to 30 percent of cases.
- Sometimes,
pathology analysis of a tumor and/or lymph nodes will reveal that the
tumor had spread more extensively than was initially apparent to the
physician, since a lymph node may be of normal size but have cancer
cells.
- This discovery results in an "upstaging" from one
TNM stage to a higher one. When this occurs, it is important to realize
that the initial TNM stage was not a "mistake," but rather a result of
the limitations of the diagnostic techniques available today. An
estimated 20 to 30 percent of head and neck cancer cases are upstaged.
What are some future directions in cancer diagnoses?
Several innovations are currently in practice or are being tested to improve our ability to diagnose laryngeal cancer.
PET Scans
Emerging Role of PET Scans in Detecting Cancer
The use of PET scans (positron emission tomography)
in cancer detection is gaining wider application and acceptance in the
medical cancer field. A PET scan, a nuclear medicine technique, can
detect cancer cells by discerning the higher metabolic rate in cancer
cells compared to other cells in the body.
Basis of the PET Scan
A radioactive sugar, injected into a patient's vein, becomes
concentrated in tumor cells because their metabolism is higher than
that of normal cells. A PET scan takes an x-ray of the area of the body
that is of concern. Tumor cells "light up" on the x-ray film because of
their concentrated radioactivity.
Combination CT Scan + PET Scan
Some medical centers have a combined CT (computed tomography)
scanner and PET (positron emission tomography) scanner, enabling the
use of both scanning technologies simultaneously. Adding a CT scanning
image to PET image – a CT-PET fusion image – provides superior
localization of cancer lesions and gives greater information about its
association with surrounding structures. Combination CT-PET fusion
scans may play a more important role in detecting repeat cancers than
in the initial detection of a tumor.
Molecular Margin Analysis
Identifying Cancer Cells Earlier and More Accurately
A major thrust of cancer research has been the enhancement of early
detection of cancer cells. Early detection leads to early treatment,
which in turn leads to better control or cure of cancer.
A Promising New Technique
Molecular margin analysis is one promising technique now being
examined in a large, multi-center study. Molecular margin analysis
involves a very sensitive laboratory technique that can detect altered
or cancerous DNA in cells. When this test is applied to the edges of
the tumor after surgical removal, it can detect cancer cells more
accurately than current-day microscopic exam by an experienced
pathologist.
Time to Full Application Still a Hurdle to Overcome
One of the main obstacles to molecular margin analysis is the time
that the laboratory takes to detect cancerous, altered DNA in the
margins. This delay makes it difficult for the surgeon to immediately
excise more tissue to ensure that all of the cancer is removed.
However, faster techniques, which have very recently been developed,
make routine use of molecular margin analysis a possible addition to
pathologic evaluation of tissues removed at surgery.
 Red FlagAny and all airway problems require immediate attention
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