View larger version
(119K):
[Click here]
|
FIGURE 7. Case example, brain tumor.
| |
Why Did FDG PET Help?
FDG PET helped by
showing that an inconclusive finding on MRI was, in fact, the result
of radiation and not residual tumor. Therefore, this patient did not
need medical or surgical intervention.
Key Management Issues.
Initial management.
Diagnosing and grading the malignancy
Determining the extent for treatment planning
Directing biopsy
Determining prognosis
Post-treatment management.
- Differential diagnosis between recurrence and radiation necrosis
- Directing biopsy (This helps to determine where in the brain to
sample the tissue, by differentiating tumor from necrosis and
edema.)
- Determining the extent of tumor in treatment planning
- Monitoring response to treatment (surgery/radiotherapy/chemotherapy)
(This involves differentiating tumor from necrosis and edema
to determine how well the treatment affected the tumor.)
Summary of Evidence for FDG PET in Brain
Tumors.
For recurrence: An estimated 31% change was noted in
management effect, based on 89 patient studies (Table
7).
View this
table:
[Click here]
|
TABLE 7 FDG PET in Brain Tumors: Results
of Literature Search
| |
Back to top.
Ovarian, Cervical, and Uterine Cancer
Disease Background.
Ovarian cancer
is the fifth leading cause of cancer death in women in the United
States, with 14,500 deaths and 25,400 new cases diagnosed each year.
Approximately one-third of all new cases will have metastatic disease
at the time of diagnosis, with another third developing clinical
metastases during the first year after surgical resection. The
current recommendation for management of patients without evidence of
metastatic disease at 1 y after diagnosis is to perform second-look
laparotomy for clinical staging and possible tumor resection. For
early-stage ovarian cancer, accurate diagnosis is very
difficult.
Cervical cancer is one of the most common cancers, accounting for
6% of all malignancies in women, with an estimated 16,000 new cases
of invasive cancer of the cervix and 5,000 deaths in the United
States each year. The prognosis for this disease is markedly affected
by the extent of disease at the time of diagnosis.
Cancer of the endometrium, a common type of cancer in women, is a
disease in which cancer cells are found in the lining of the uterus
(endometrium). Cancer of the endometrium is different from cancer of
the muscle of the uterus (sarcoma of the uterus). Cancer of the
endometrium is the most common pelvic gynecologic malignancy and
accounts for 13% of all cancers in women. It is a highly curable
tumor.
Case Example.
A 50-y-old woman with
a history of ovarian cancer showed rising tumor markers in an annual
blood test that looked for possible tumor recurrence. A follow-up CT
scan was unable to find the source of the recurrence. An FDG PET
study showed that the tumor had metastasized to the right lobe of the
liver (Fig.
8, arrows on site of metastasis viewed on 4 different sections
through the whole body). No other areas of metastasis were seen.
View larger version
(119K):
[Click here]
|
FIGURE 8. Case example, ovarian, cervical,
and uterine cancer.
| |
Why Did FDG PET Help?
FDG PET showed that the
blood study was correct (it was not falsely elevated) and that the
source of recurrence was the liver. This patient was confirmed
through follow-up to have recurrence in the liver.
Key Management Issues.
Staging lymph nodes
Identifying recurrent disease after surgery and radiation
Assessing response to treatment
Summary of Evidence for FDG PET in Ovarian, Uterine,
and Cervical Cancer.
For recurrence: An estimated 17% change
was noted in management effect, based on 30 patient studies (Table
8).
View this
table:
[Click here]
|
TABLE 8 FDG PET in Ovarian, Cervical, and
Uterine Cancer: Results of Literature Search
| |
Back to top.
Bladder Cancer
Disease Background.
Bladder cancer
is a disease in which cancer cells originate from the bladder wall.
Approximately 70%-80% of patients with newly diagnosed bladder cancer
will present with superficial bladder tumors. Those tumors that are
noninvasive are often curable, and those that are deeply invasive are
sometimes cured by surgery, radiation, or a combination of
modalities that includes chemotherapy. Some patients with distant
metastases have achieved long-term complete response after treatment
with combination chemotherapy regimens. The major prognostic
factors in carcinoma of the bladder are the depth of invasion into
the bladder wall and the degree of differentiation of the tumor.
Transurethral surgery, intravesical medications, and cystectomy
(bladder removal) have been used in the management of patients
with superficial tumors and are all associated with 5-y survival
rates for 55%-80% of patients treated. As with many cancers,
the key to management is determining if the bladder cancer has
spread beyond the bladder to the local lymph nodes or to distant
parts of the body.
Case Example.
A patient with cancer
of the bladder was scanned for staging purposes. Focal increased FDG
uptake was seen within the posterior aspect (back) of the bladder,
indicating primary disease only (Fig.
9, arrow). Mild accumulation of FDG also was seen around a right
total hip replacement (Fig.
9A), possibly indicating active inflammation or infection,
although the patient did not complain of any hip pain.
View larger version
(28K):
[Click here]
|
FIGURE 9. Case example, bladder cancer.
Reproduced, with permission, from Maisey et al. Atlas of Clinical
Positron Emission Tomography. London, UK: Arnold, Hodder
Headline Group; 1999.
| |
Why did FDG PET help?
FDG PET helped by
showing no evidence of cancer spread beyond the bladder, so that
local treatment (e.g., removal of the bladder) likely would benefit
the patient.
Key Management Issues.
Primary nodal staging
Systemic metastases staging
Summary of Evidence for FDG PET in Bladder
Cancer.
For staging: An estimated 17% change was noted in
management effect, based on 12 patient studies (Table
9).
View this
table:
[Click here]
|
TABLE 9 FDG PET in Bladder Cancer: Results
of Literature Search
| |
For
recurrence: An estimated 17% change was noted in management effect,
based on 12 patient studies (Table
9). Because management effect for both staging and recurrence is
based upon the same single study of 12 patients, results should be
interpreted with caution.
Back to top.
Gastroesophageal Cancer
Disease Background (Gastric
Cancer).
Cancer of the stomach, also called gastric cancer,
is a disease in which cancer cells originate from the tissues of the
stomach. Cancer of the distal half of the stomach has been
decreasing in the United States since the 1930s. However, in the last
2 decades, the incidence of cancer of the cardia and
gastroesophageal junction (upper half of the stomach) has been rising
rapidly. The incidence of this cancer, especially in patients
younger than 40 y, has increased dramatically. In localized distal
gastric cancer, >50% of patients can be cured. However, early
stage disease accounts for only 10%-20% of all cases diagnosed
in the United States. The remaining patients present with metastatic
disease in either regional or distant sites. The overall survival
rate in these patients at 5 y ranges from almost no survival
for patients with disseminated disease to almost 50% survival
for patients with localized distal gastric cancers confined to
resectable regional disease. Even with apparent localized disease,
the 5-y survival rate of patients with proximal gastric cancer is
only 10%-15%. Although the treatment of patients with disseminated
gastric cancer may result in palliation of symptoms and some
prolongation of survival, long remissions are uncommon. Radical
surgery represents the standard form of therapy with curative intent.
Lesser surgical procedures also may play important roles in
palliative therapy for patients with gastric cancer. Neoadjuvant or
postoperative chemotherapy and/or radiation therapy are under
clinical evaluation.
Disease Background (Esophageal
Cancer).
Carcinoma of the esophagus is increasing rapidly in
frequency in the west, with the rise most apparent in patients with
adenocarcinoma of the esophagus. Much of the increase is thought to
be related to reflux esophagitis and Barrett´s esophagus
(conditions in which acid from the stomach damages the esophagus),
but the exact cause is uncertain. Adenocarcinoma of the esophagus
is now more prevalent than squamous cell carcinoma in the United
States and western Europe, with most tumors located in the distal
esophagus. Esophageal cancer is a treatable disease but is rarely
curable. The overall 5-y survival rate in those cases amenable
to surgery ranges from 5%-20%. The occasional patient with very
early disease has a better chance of survival. Primary treatment
modalities include surgery alone or chemotherapy with radiation
therapy. Combined modality therapy (chemotherapy plus surgery or
chemotherapy and radiation therapy plus surgery) is under clinical
evaluation.
Case Example (Gastric Cancer).
A
35-y-old patient underwent surgery for gastric cancer. At the time of
surgery, a portion of the stomach was removed around the tumor site.
During surgery, it was noted that lymph nodes near the stomach also
were involved. The patient therefore underwent chemotherapy to treat
for spread of the gastric cancer. A CT scan was performed after 6 mo
and showed questionable enlargement of lymph nodes in the abdomen. An
FDG PET scan was ordered to determine whether the lymph nodes seen on
the CT scan were in fact consistent with tumor involvement. The FDG
PET scan (Fig.
10) shows several areas of focal increased FDG accumulation
in the midabdomen (arrow), confirming tumor recurrence.
View larger version
(54K):
[Click here]
|
FIGURE 10. Case example, gastric cancer.
| |
Why Did FDG PET Help?
FDG PET confirmed that
the questionable findings on CT scan, in fact, were likely to be
tumor. Sometimes the CT scan can show lymph node enlargement when no
tumor has recurred. In the case shown, there was likely to be tumor
recurrence, and the patient now could be managed with the maximal
information in hand.
Case Example (Esophageal Cancer).
A
59-y-old man with known esophageal cancer was referred for FDG PET
scanning before surgery. CT demonstrated the presence of the primary
tumor but no spread of disease. FDG PET showed uptake in the primary
tumor (Fig.
11B, lower arrow) and a lymph node near the trachea (Fig.
11A, arrow, and 11B, upper arrow). The esophageal cancer had
spread beyond the esophagus.
View larger version
(92K):
[Click here]
|
FIGURE 11. Case example, esophageal
cancer. Reproduced, with permission, from Maisey et al. Atlas of
Clinical Positron Emission Tomography. London, UK: Arnold,
Hodder Headline Group; 1999.
| |
Why Did FDG PET Help?
FDG PET showed that the
cancer had spread beyond the esophagus. Esophageal surgery alone,
therefore, was not the best way to manage this patient.
Key Management Issues.
Staging for possible spread of tumor
Assessing for recurrence
Summary of Evidence for FDG PET in Gastroesophageal
Cancer.
For diagnosis: An estimated 14% change was noted in
management effect, based on 99 patient studies with 276 lesion sites
(Table
10).
View this
table:
[Click here]
|
TABLE 10 FDG PET in Gastroesophageal
Cancer: Results of Literature Search
| |
For
staging: An estimated 20% change was noted in management effect,
based on 229 patient studies (Table
10).
For diagnosis/staging: An estimated 14% change was noted in
management effect, based on 109 patient studies (Table
10).
Back to top.
Hepatocellular Cancer
Disease Background.
Adult primary
liver cancer is a disease in which cancer cells start to grow in the
tissues of the liver. People who have hepatitis B or C or cirrhosis,
a disease of the liver, are more likely than other people to get
adult primary liver cancer. Primary liver cancer is different from
cancer that has spread from another place in the body to the liver.
Hepatocellular carcinoma is a relatively uncommon tumor in the United
States, although its incidence is rising. It is the most common
cancer in some other parts of the world. Hepatocellular carcinoma is
potentially curable by surgical resection, but surgery is the
treatment of choice for only the small fraction of patients with
localized disease. Prognosis depends on the degree of local tumor
replacement and the extent of liver function impairment. Therapy
other than surgical resection is best administered as part of a
clinical trial. Hepatocellular carcinoma is associated with
cirrhosis in 50%-80% of patients. Five percent of patients with
cirrhosis eventually develop hepatocellular cancer, which is
often multifocal. Childhood liver cancer, also called hepatoma,
is a rare disease in which cancer cells are found in the tissues
of a child´s liver. Two types of cancer (hepatoblastoma and
hepatocellular cancer) start in the liver and are identified by the
way the cancer cells look under a microscope. Hepatoblastoma is more
common in children younger than 3 y and may have a genetic cause. The
overall survival rate for children with hepatoblastoma is 70% but is
only 25% for hepatocellular carcinoma.
Case Example.
A patient presented to
his doctor with vague abdominal symptoms. The work-up, which
eventually included a CT scan, revealed that the patient had enlarged
lymph nodes near the portal region of the liver. An FDG PET scan was
ordered to further evaluate for tumor. The scan revealed uptake of
FDG within a focus in the right lobe of the liver (Fig.
12, center). No other foci were present, indicating that the
tumor was confined to the liver. The patient went on to have an
appropriate surgery for localized hepatoma.
View larger version
(47K):
[Click here]
|
FIGURE 12. Case example, hepatocellular
cancer.
| |
Why Did FDG PET Help?
FDG PET indicated that
the tumor was localized and that the patient was a candidate for
surgery.
Key Management Issues.
Distinguishing between cirrhosis and hepatoma
Assessing response to treatment and differentiating tumor from necrosis, edema, and scarring
Identifying multifocal lesions
Summary of Evidence for FDG PET in Hepatocellular
Cancer.
For staging: An estimated 60% change was noted in
management effect, based on 20 patient studies (Table
11).
View this
table:
[Click here]
|
TABLE 11 FDG PET in Hepatocellular Cancer:
Results of Literature Search
| |
Back to top.
Muscle and Connective Tissue Tumors
Disease Background.
Adult soft
tissue sarcoma is a disease in which cancer cells are found in the
soft tissue of part of the body. The soft tissues of the body include
the muscles, connective tissues (tendons), vessels that carry blood
or lymph, joints, and fat. The prognosis for a patient with adult
soft tissue sarcomas depends on several factors, including the
patient´s age and the size, histologic grade, and stage of the tumor.
Factors associated with a poorer prognosis are age older than 60 y,
tumors >5 cm, and high-grade histology. Although low-grade tumors
usually are curable by surgery alone, higher-grade sarcomas (as
determined by the mitotic index and the presence of hemorrhage and
necrosis) are associated with higher local treatment failure rates
and increased metastatic potential. Soft tissue sarcomas are rare in
children and adolescents. There are many different kinds of soft
tissue sarcoma, depending on the soft tissue in which the cancer
begins. Rhabdomyosarcoma is the most common type of childhood soft
tissue sarcoma. It begins in muscles around the bone and can be found
anywhere in the body.
Case Example.
A 41-y-old man had
surgery and radiotherapy, first for a liposarcoma in the right thigh
and 3 mo later for a solitary metastasis in the abdomen. He developed
recurrent disease within the right thigh and was referred for FDG PET
scanning. The FDG PET scan showed focal increased metabolism within
the right thigh (Fig.
13A, B, and C), indicative of recurrent disease, surrounded
by diffuse metabolism secondary to inflammation after surgery.
High metabolism of FDG was also noted within lung metastases
(Figs.
13C and D).
View larger version
(47K):
[Click here]
|
FIGURE 13. Case example, muscle and
connective tissue tumors. Reproduced, with permission, from Maisey
et al. Atlas of Clinical Positron Emission Tomography.
London, UK: Arnold, Hodder Headline Group; 1999.
| |
Why Did FDG PET Help?
The FDG PET scan
indicated lung and mediastinal metastases, in addition to local
disease in the thigh. This meant that the patient would not benefit
from treatment of the thigh region alone and would likely require
chemotherapy.
Key Management Issues.
Following up sarcoma treatment
Grading sarcoma
Separating benign from malignant masses
Selecting biopsy sites
Assessing extent of sarcomas
Summary of Evidence for FDG PET in Muscle and
Connective Tissue Tumors.
Management change data for
diagnosis and staging and other applications are not directly
available from the literature (Table
12).
View this
table:
[Click here]
|
TABLE 12 FDG PET in Muscle and Connective
Tissue Tumors: Results of Literature Search
| |
Back to top.
Pancreatic Cancer
Disease Background.
Pancreatic
carcinoma is common in the United States, with approximately 30,000
patients each year diagnosed with pancreatic adenocarcinomas.
Patients with inflammatory processes in the pancreas (pancreatitis)
but no cancer can sometimes have high FDG uptake that is
indistinguishable from cancers and, thus, must be differentiated from
patients with cancer. FDG PET is being applied increasingly in
pancreatic cancer diagnosis. Considering the very poor prognosis of
pancreatic carcinomas, PET´s greatest role may prove to be in
helping to characterize masses appearing in the pancreas, as
opposed to more general tumor staging. This is an active area of
current investigation.
Case Example.
A 52-y-old woman with
a calcified pancreatic mass on CT (Fig.
14A, arrow) was referred for FDG PET scanning because of
rising blood tumor markers. No uptake of FDG was seen within the
mass (Fig.
14B). The patient was treated conservatively, under the
assumption that she had inflammation of the pancreas (pancreatitis).
Follow-up over 2 y with CT revealed no changes, indicating that
FDG PET was correct and no tumor existed.
View larger version
(60K):
[Click here]
|
FIGURE 14. Case example, pancreatic
cancer. Reproduced, with permission, from Maisey et al. Atlas of
Clinical Positron Emission Tomography. London, UK: Arnold,
Hodder Headline Group; 1999.
| |
Why Did FDG PET Help?
FDG PET demonstrated
that there was no pancreatic tumor, sparing the patient pancreatic
surgery.
Key Management Issues.
Differentiating chronic pancreatic masses from cancer
Staging nodal and liver metastases
Assessing response to chemotherapy
Summary of Evidence for FDG PET in Pancreatic
Cancer.
For diagnosis: An estimated 50% change was noted in
management effect, based on 26 patient studies (Table
13).
View this
table:
[Click here]
|
TABLE 13 FDG PET in Pancreatic Cancer:
Results of Literature Search
| |
For
diagnosis/staging: An estimated 43% change was noted in management
effect, based on 65 patient studies (Table
13).
For staging: An estimated 36% change was noted in management
effect, based on 33 patient studies (Table
13).
For recurrence: An estimated 53% change was noted in management
effect, based on 19 patient studies (Table
13).
For monitoring response: An estimated 16% change was noted in
management effect, based on 19 patient studies (Table
13).
Back to top.
Prostate Cancer
Disease Background.
Prostate cancer
rates increased 141.8% between 1973 and 1994. In 1998, new prostate
cancer cases totaled 184,500, or, in other terms, one new case every
3 min. Prostate cancer continues to be the most frequently occurring
malignancy (aside from skin cancers), representing 29% of all new
cancer cases in American men. One out of every six men is at lifetime
risk for prostate cancer. Approximately every 13 min, a life is lost
to prostate cancer in the United States. African-Americans have the
highest prostate cancer incidence rates in the world, exceeding
those for white males in the United States by 34%. Prostate
cancer mortality rates are two times higher for African-American
men than for white American men.
Case Example.
A 75-y-old man, who
was diagnosed with prostate cancer, was followed by blood levels for
prostate specific antigen (PSA, a prostate tumor marker). A rising
PSA was followed up with a CT scan (Fig.
15, left), which revealed lymph node involvement in the pelvis
near the removed prostate. An FDG PET study confirmed what was seen
on CT and, in addition, showed spread of cancer into the abdomen and
chest (Fig.
15, middle and right).
View larger version
(35K):
[Click here]
|
FIGURE 15. Case example, prostate cancer. | |
Why Did FDG PET Help?
FDG PET helped because
it showed that the cancer had spread to distant sites and that local
radiation to the pelvis alone was not likely to benefit the
patient.
Key Management Issues.
Further evaluation of equivocal bone lesions found with conventional imaging
Differentiating benign from malignant lesions in bone
Assessing treatment response when lesion is imaged initially
Identifying metastatic disease in soft tissue
Summary of Evidence for FDG PET in Prostate
Cancer.
Management change data for staging patients are not
directly available from the literature (Table
14).
View this
table:
[Click here]
|
TABLE 14 FDG PET in Prostate Cancer:
Results of Literature Search
| |
Back to top.
Renal Cell Cancer
Disease Background.
Renal cell
cancer, also called renal adenocarcinoma or hypernephroma, can often
be cured if diagnosed and treated when still localized to the kidney
and to immediately surrounding tissue. The probability of cure is
directly related to the stage or degree of tumor dissemination. Even
when regional lymphatics or blood vessels are involved with tumor, a
significant number of patients can achieve prolonged survival and
probable cure. When distant metastases are present, disease-free
survival is poor, although occasionally, patients will survive after
surgical resection of all known tumor. Because a majority of patients
are diagnosed when the tumor is still relatively localized and
amenable to surgical removal, approximately 40% of all patients with
renal cancer survive 5 y. Occasionally, patients with locally
advanced or metastatic disease may exhibit indolent courses lasting
several years. Late tumor recurrence many years after initial
treatment occurs occasionally. Renal cell cancer is one of the few
tumors in which well-documented cases of spontaneous tumor
regression in the absence of therapy exist, but this occurs very
rarely and may not lead to long-term survival. Surgical resection
is the mainstay of treatment of this disease. Even in patients
with disseminated tumor, locoregional forms of therapy may play
an important role in palliating symptoms of the primary tumor
or of ectopic hormone production. Systemic therapy has demonstrated
only limited effectiveness.
Case Example.
A 59-y-old man with a
history of metastatic renal cell cancer and left kidney removal
developed left-sided flank pain. Abdominal-pelvic CT was negative on
initial review (Fig.
16, bottom row). FDG PET revealed a focus in the apex of the
right lung and in the left flank (Fig.
16, top row, arrows). Because of the abnormality in the region of
the left flank, the CT was reviewed again and a mass located in the
posterior abdominal wall was found. Biopsy revealed metastasis from
renal cell cancer.
View larger version
(71K):
[Click here]
|
FIGURE 16. Case example, renal cell
cancer.
| |
Why Did FDG PET Help?
FDG PET showed a lesion
missed on CT and also showed that the renal cell cancer had spread to
the lungs. The patient, therefore, could be managed better with
systemic therapy and, because of the spread of the disease, was not
likely to do well.
Key Management Issues.
Detecting metastatic disease
Assessing response of metastases to chemotherapy
Determining nature of renal masses
Summary of Evidence for FDG PET in Renal Cell
Cancer.
Management change data for diagnosis and staging and
other applications are not directly available from the literature (Table
15).
View this
table:
[Click here]
|
TABLE 15 FDG PET in Renal Cancer: Results
of Literature Search | |
Back to top.
Testicular Cancer
Disease Background.
Cancer of the
testicle, a rare type of cancer, is a disease in which cancer cells
are found in the tissues of one or both of a man´s testicles. Cancer
of the testicle is the most common cancer in men 15-35 y old. Men who
have an undescended testicle (a testicle that has never moved down
into the scrotum) are at higher risk of developing cancer of the
testicle. This is true even if surgery has been performed to place
the testicle in the appropriate place in the scrotum. Prognosis and
choice of treatment depend on the stage of the cancer and the
patient´s general state of health.
Case Example.
A 27-y-old man with
testicular cancer had his left testicle removed. An abdominal CT scan
indicated an enlarged lymph node in the lower abdomen. A CT-guided
biopsy was performed but did not reveal cancer. An FDG PET scan was
ordered to make sure the biopsy was not wrong. The scan showed a
focus of activity in the abdominal lymph node (Fig.
17, arrows), suggesting cancer spread. A repeat biopsy confirmed
tumor in the abdominal lymph node site.
View larger version
(77K):
[Click here]
|
FIGURE 17. Case example, testicular
cancer.
| |
Why Did FDG PET Help?
FDG PET showed that the
biopsy was wrong, and, in fact, tumor was present in the abdomen.
Furthermore, the tumor did not appear to have spread elsewhere.
Knowing the presence of tumor in that region changed management for
the patient, who would have received only testicular surgery but now
could receive additional treatment for spreading testicular
cancer.
Key Management Issues.
Monitoring response to treatment
Staging of primary disease
Assessing residual mass
Further evaluating raised markers
Summary of Evidence for FDG PET in Testicular
Cancer.
For staging: An estimated 22% change was noted in
management effect, based on 27 patient studies (Table
16).
View this
table:
[Click here]
|
TABLE 16 FDG PET in Testicular Cancer:
Results of Literature Search
| |
For
recurrence: An estimated 51% change was noted in management effect,
based on 53 patient studies (Table
16).
Back to top.
Thyroid Cancer
Disease Background.
Cancer of the
thyroid is a disease in which cancer cells are found in the tissues
of the thyroid gland. People who have been exposed to large amounts
of radiation or who have had radiation treatment for medical problems
in the head and neck have a higher chance of getting thyroid cancer.
The cancer may not occur until 20 y or longer after radiation
treatment. The four main types of cancer of the thyroid are:
papillary, follicular, medullary, and anaplastic. The chance of
recovery depends on the type of thyroid cancer, whether it is only in
the thyroid or has spread to other parts of the body (stage), and the
patient´s age and overall health. Some types of thyroid cancer grow
much faster than others. Although thyroid cancer is relatively
uncommon, it is nonetheless the most common malignancy of the
endocrine system. Differentiated tumors (papillary or follicular)
are highly treatable and usually curable. Poorly differentiated
cancers (medullary or anaplastic) are much less common but
aggressive, metastasize early, and have a much poorer prognosis. The
incidence of this malignancy has been increasing over the last
decade. The prognosis for differentiated carcinoma is better for
patients younger than 40 y and who have no extracapsular extension
or vascular invasion. Age appears to be the single most
important prognostic factor. Thyroid cancer commonly presents as a
cold nodule within the thyroid gland. The overall incidence of
cancer in a cold nodule is 12%-15% but is higher in patients
younger than 40 y.
Case Example.
A 62-y-old patient
underwent surgery of the left thyroid for thyroid cancer. Routine
yearly monitoring revealed elevated blood levels of calcitonin. A CT
scan was ordered and was normal. An FDG PET scan revealed increased
FDG accumulation in the neck (Fig.
18, arrows), which was confirmed by biopsy to be residual thyroid
cancer.
View larger version
(74K):
[Click here]
|
FIGURE 18. Case example, thyroid cancer.
Reproduced, with permission, from Maisey et al. Atlas of Clinical
Positron Emission Tomography. London, UK: Arnold, Hodder
Headline Group; 1999.
| |
Why Did FDG PET Help?
FDG PET identified the
source of the rising tumor marker and thereby allowed removal of
residual thyroid cancer.
Key Management Issues.
Further evaluation when whole-body 131I scan is negative
but thyroglobulin (Tg) levels are rising in a patient with
known differentiated thyroid cancer
Further evaluation for medullary thyroid cancer when
rising calcitonin level and initial imaging with
dimercaptosuccinic acid V, octreoscan, or
metaiodobenzylguanidine is negative.
Summary of Evidence for FDG PET in Thyroid
Cancer.
For staging: An estimated 22% change was noted in
management effect, based on 60 patient studies (Table
17).
View this
table:
[Click here]
|
TABLE 17 FDG PET in Thyroid Cancer:
Results of Literature Search
| |
For
diagnosis/staging: An estimated 9% change was noted in management
effect, based on 58 patient studies (Table
17).
For recurrence: An estimated 53% change was noted in management
effect, based on 21 patient studies (Table
17).
Back to top.
Unknown Primary Tumor
Disease Background.
Detection of the
unknown primary lesion is very difficult. In many cases, patients
present with obvious metastatic disease, often adenocarcinoma, in
which the location of the primary lesion may never be found. In some
cases, knowledge of the primary site is important, because the type
of treatment may vary (e.g., breast cancers are more responsive to
some treatments than are renal cancers). This knowledge also can be
helpful in resection or treatment for cure of the primary lesion and
metastases (e.g., head and neck cancers). FDG PET is useful in
locating primary tumors after metastatic disease has appeared in
regional lymph nodes. FDG PET is being applied increasingly in the
search for unknown primary lesions. This application is still in
evolution, but FDG PET should be considered strongly in the work-up
of the unknown primary.
Case Example.
A 49-y-old woman
presented with lymph node enlargement in the neck. Physical
examination, CT, and mammography performed twice all failed to reveal
the source of the primary cancer. An FDG PET study showed that the
primary cancer was in the left breast (nonpalpable). The lymph node
involvement was not seen in the sections shown in Figure
19.
View larger version
(83K):
[Click here]
|
FIGURE 19. Case example, unknown primary
tumor.
| |
Why Did FDG PET Help?
FDG PET identified the
source of the patient´s cancer when no other study could do so,
thereby allowing the patient to be treated appropriately for breast
cancer with spread to the lymph nodes.
Key Management Issues.
Identifying primary site to determine treatment and evaluate
for possible resection
Summary of Evidence for FDG PET in Unknown Primary
Cancer.
For staging: An estimated 29% change was noted in
management effect, based on 285 patient studies (Table
18). (See Table
19 for the results of the literature search on FDG PET in
miscellaneous tumors.)
View this
table:
[Click here]
|
TABLE 18 FDG PET in Unknown Primary
Cancer: Results of Literature Search
| |
View this
table:
[Click here]
|
TABLE 19 FDG PET in Miscellaneous Tumors:
Results of Literature Search
| |
Summary
Table
20 is a summary of results from the literature search on FDG PET
in cancer.
Back to top.
