Cancer of the Nasopharynx
Most nasopharyngeal cancers are squamous cell tumors, but some
are "dysplastic" cancers whose cellular derivation is
unclear. Cancer of the nasopharynx is rare in the United States
except among southern Chinese immigrants. People of south China
appear to be genetically presupposed to this illness, but also
may increase their risk by eating large amounts of salted fish.
Another risk factor appears to be previous infection with the
Epstein-Barr virus (the cause of infectious mononucleosis).
The early symptoms of nasopharynx cancer tend to be vague, "cold-like"
symptoms. including nasal stuffiness. Because the nasopharynx
is not easily observed on a routine examination, the diagnosis
is not often made as early as would be wished. As the tumor grows
it commonly blocks the Eustachian tube, leading to unilateral
hearing loss, and it spreads to neck lymph nodes on the same side,
producing a lump in the neck. Specialized examination by the head
and neck surgeon includes nasal endoscopy to look directly into
the nasopharynx and obtain biopsies of suspicious lesions.When
yielding positive results, the head and neck exam will be supplemented
with imaging studies to assess the size of the tumor and seek
evidence of spread. These tests may include CT
scan, MRI
scan, radionuclide bone scan and/or PET
scan.
The deep location of the nasopharynx and its proximity to the
brain make surgical treatment of the primary tumors impractical.
Most nasopharyngeal tumors are very responsive to radiation therapy
which is the main mode of therapy. Patients with more advanced
lesions may be treated systemically with chemotherapy agents prior
to the radiation treatments.
Cancer of the Oropharynx
The oropharynx includes the soft palate, the bases of the tongue,
the palatine tonsils and the posterior pharyngeal wall directly
behind the mouth. More than 90% of the cancers in this area are
squamous cell tumors. The main risk factors for oropharyngeal
cancer are tobacco and alcohol use. While 85% of head and neck
cancer is related to tobacco use, the combined use of tobacco
and alcohol makes for even higher risk. Previous exposure to human
papilloma virus or Epstein-Barr virus may also increase risk.
Symptoms are varied, but may include:
- persistent sore throat
- hoarseness
- feeling of something "caught" in the throat
- pain or bleeding from the throat
- ear or jaw pain
- a lump in the neck
Although any of these symptoms can be the result of non-cancerous
conditions, they should prompt a trip to the doctor, and in all
likelihood, an evaluation by the head and neck surgeon. Along
with a standard physical examination of the head and neck structures,
the specialist will perform and endoscopic examination of the
pharynx ("pharyngoscopy"), and will biopsy any lesions
discovered. Thereafter, patient's with positive biopsies will
undergo several imaging studies (xrays and scans) to help stage
their disease and direct treatment.
Staging
TNM is an abbreviation for tumor (T), node (N), and metastasis
(M). Doctors look at these three factors to determine the stage
of cancer.
T0: No evidence of a tumor is found.
Tis: a stage called "carcinoma in situ", a very early
cancer found only in the surface layer of tissue.
T1: a tumor that is 2 cm or less at its greatest dimension.
T2: a tumor that is larger than 2 cm, but not larger than 4 cm.
T3: a tumor that is larger than 4 cm.
T4a: a tumor that has spread to the larynx, tongue, or jawbone.
T4b: The tumor has moved into the nasopharynx, skull base, or
nearby arteries and muscles.
The "N" in the TNM system stands for lymph nodes, the
small, bean-shaped organs that help fight infection.
N0: no evidence of cancer in the regional nodes.
N1: cancer has spread to a single node on the same side as the
tumor and the cancer in the node is 3 cm or smaller.
N2: any of these following:
N2a: cancer has spread to a single lymph node on the same side
as the tumor, is larger than 3 cm, but not larger than 6 cm.
N2b: cancer has spread to more than one node on the same side
as the tumor, but none measure larger than 6 cm.
N2c: cancer has spread to more than one lymph node on either side
of the neck, but none measure larger than 6 cm.
N3: cancer found in lymph nodes is larger than 6 cm.
The "M" in the TNM system describes cancer that has
spread to other parts of the body.
MX: distant metastasis cannot be evaluated.
M0: cancer has not spread to other parts of the body.
M1: cancer t has spread to other parts of the body.
Stages using TNM
Stage 0: carcinoma in situ (Tis), with no spread to lymph nodes
(N0) and no distant metastasis (M0).
Stage I: a small tumor (T1), with no spread to lymph nodes (N0)
and no distant metastasis (M0).
Stage II: a tumor that is smaller than 4 cm (T2), and has not
spread to lymph nodes (N0) or to distant parts of the body (M0).
Stage III: all larger tumors (T3), with no spread to lymph nodes
(N0) or metastasis (M0), as well as smaller tumors (T1, T2) that
have spread to lymph nodes (N1), but have no metastasis (M0).
Stage IVA: any invasive tumor (T4a) with either no lymph node
involvement (N0) or spread to a single, same-sided node (N1),
but no metastasis (M0).
It is also used for any tumor (T) with more significant node involvement
(N2), but no metastasis (M0).
Stage IVB: any tumor (T) with extensive nodal involvement (N3),
but no metastasis (M0).
Stage IVC: there is evidence of distant spread (M1).
Besides staging a tumor, doctors also assess what is called its
"grade." Because normal tissues are made up of many
different types of cells grouped together, (something called "differentiation"),
tumors are examined microscopically to see if their cells show
relatively more or less differentiation. Tumors with less differentiation
are more aggressive.
GX: the grade cannot be determined
G1: the cells look more like normal tissue (well differentiated).
G2: the cells are moderately differentiated.
G3: the cells don't look like normal tissue at all (poorly differentiated).
Treatment
The primary treatments for oropharyngeal cancers are surgery
and/or radiation therapy. In surgery, the doctor will remove the
tumor together with some surrounding normal tissue. Such "radical"
surgery is standard in most cancer treatment since the doctors
need to be as certain as possible that all the local disease is
removed. In some cases, local treatment can be accomplished employing
trans-oral
laser microsurgery. This technique may allow the surgeon to
sacrifice less normal tissue. When trans-oral treatment is not
possible do to the size or invasion of the tumor, the head and
neck surgeon may divide the lower jaw to gain surgical access.
If the bone itself is involved with the tumor, some portion of
the jaw will be removed as a part of the "specimen."
If there is reason to suspect spread to local lymph nodes, some
form of "lymph node dissection" may be carried out.
The nature and extent of lymph node removal will vary from removal
of just a few nodes near the area of the tumor, to "radical
neck dissection" where nearly all neck nodes are removed.
If the tissue removed leaves a defect that cannot be directly
repaired, it may be necessary for the head and neck surgeon or
a reconstructive surgical colleague to transfer tissues from elsewhere
on the body to substitute for those removed.This may be appropriate
to minimize the cosmetic consequences of surgery, or, more often,
as a way to reduce the functional impairment that could follow
healing ((e.g. potential impairments of speech or swallowing).
Radiation therapy can destroy cancer cells and
shrink tumors. It may be given as an adjunct to surgical treatment,
or be used as the primary form of therapy for the local tumor.
Radiation is administered either externally and internally. External-beam
radiation involves the use of a machine to focus a radiation beam
on the tumor from outside the body. Internal radiation therapy,
("interstitial radiation" or "brachytherapy",
employs tiny pellets or rods containing radioactive materials
that are surgically implanted in the cancer site. These are removed
after several days, after which,the patient can leave the hospital.
A new method of external radiation called "intensity modulated
radiation therapy" (IMRT), allows delivery of larger doses
to the tumor while reducing the damage to healthy cells.
It is important that the head and neck cancer patient who needs
radiation be prepared by an oncologic dentist.
(See
Dentistry in Head and Neck Cancer)
In some cases, local treatments (surgery and/or radiation) may
be supplemented by "systemic" treatment with chemotherapy.
Chemotherapy is administered by mouth or by injection,
introducing medicines that are able to travel throughout the body
and potentially destroy any cancer cells that "broke away"
and escaped the local treatment. When this therapy is given after
local treatment as a supplement, it is known as "adjuvant"
chemotherapy. Treatments given to shrink a tumor before local
surgery or radiation are used is called, "neo-adjuvant"
therapy.
Cancer of the Hypopharynx
The hypopharynx is the lowest part of the throat, commonly referred
to as the "gullet." Because it surrounds the larynx,tumors
arising in the hypopharynx often involve the voice box. Even for
those early tumors that do not, treatment of the tumor must take
into account this very important nearby organ. It is convenient,
therefore, to consider cancers of the hypopharynx and larynx together.
Please
click here to learn about Cancer of the Hypopharynx and Larynx.
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