C h a p t e r 7
Neoplasia
147
Screening, Diagnosis, and
Treatment
Advances in the screening, diagnosis, and treatment
of cancer have boosted 5-year survival rates to nearly
64%. When treatment cannot cure the disease, it may be
used to slow its progression or provide palliative care.
Screening
Screening represents a secondary prevention measure
for the early recognition of cancer in an otherwise
asymptomatic population.
50,51
Screening can be achieved
through observation (e.g., skin, mouth, external genita-
lia), palpation (e.g., breast, thyroid, rectum and anus,
prostate, lymph nodes), and laboratory tests and pro-
cedures (e.g., Papanicolaou [Pap] smear, colonoscopy,
mammography). It requires a test that will specifically
detect early cancers or premalignancies, is cost effective,
and results in improved therapeutic outcomes. For most
cancers, stage at presentation is related to curability,
with the highest rates reported when the tumor is small
and there is no evidence of metastasis. For some tumors,
however, metastasis tends to occur early, even from a
small primary tumor. Unfortunately, no reliable screen-
ing methods are currently available for many cancers.
Cancers for which current screening or early detection
has led to improvement in outcomes include cancers of
the breast (breast self-examination and mammography,
discussed in Chapter 40), cervix (Pap smear, Chapter 40),
colon and rectum (rectal examination, fecal occult
blood test, and flexible sigmoidoscopy and colonoscopy,
Chapter 29), prostate (prostate-specific antigen test-
ing and transrectal ultrasonography, Chapter 39), and
malignant melanoma (self-examination, Chapter 46).
While not as clearly defined, it is recommended that
screening for other types of cancers such as cancers of
the thyroid, testicles, ovaries, lymph nodes, and oral cav-
ity be done at the time of periodic health examinations.
Diagnostic Methods
The methods used in the diagnosis and staging of can-
cer are determined largely by the location and type of
cancer suspected. They include blood tests for tumor
markers, cytologic studies, tissue biopsy, and gene pro-
filing techniques as well as medical imaging, which is
discussed with specific cancers later in this text.
Tumor Markers
Tumor markers are antigens expressed on the surface
of tumor cells or substances released from normal cells
in response to the presence of tumor.
2
Some substances,
such as hormones and enzymes, that are normally pro-
duced by the involved tissue become overexpressed as
a result of cancer. Tumor markers are used for screen-
ing, establishing prognosis, monitoring treatment, and
detecting recurrent disease. Table 7-4 identifies some of
the more commonly used tumor markers and summa-
rizes their source and the cancers associated with them.
TABLE 7-4
Tumor Markers
Marker
Source
Associated Cancers
Oncofetal Antigens
α
-Fetoprotein (AFP)
Fetal yolk sac and gastrointestinal
structures early in fetal life
Primary liver cancers; germ cell cancer
of the testis
Carcinoembryonic antigen (CEA)
Embryonic tissues in gut, pancreas,
and liver
Colorectal cancer and cancers of the
pancreas, lung, and stomach
Hormones
Human chorionic gonadotropin (hCG)
Hormone normally produced by placenta Gestational trophoblastic tumors; germ
cell cancer of testis
Calcitonin
Hormone produced by thyroid
parafollicular cells
Thyroid cancer
Catecholamines (epinephrine,
norepinephrine) and metabolites
Hormones produced by chromaffin cells
of the adrenal gland
Pheochromocytoma and related tumors
Specific Proteins
Monoclonal immunoglobulin
Abnormal immunoglobulin produced
by neoplastic cells
Multiple myeloma
Prostate-specific antigen (PSA)
Produced by the epithelial cells lining
the acini and ducts of the prostate
Prostate cancer
Mucins and Other Glycoproteins
CA-125
Produced by müllerian cells of ovary
Ovarian cancer
CA-19-9
Produced by alimentary tract epithelium Cancer of the pancreas, and colon
Cluster of Differentiation
CD antigens
Present on leukocytes
Used to determine the type and level of
differentiation of leukocytes involved
in different types of leukemia and
lymphoma
