Cancer Symptoms, Types, Diagnosis
Cancer Symptoms
While advanced cancer may cause pain, it is not always
the first symptom. Roughly, cancer symptoms can be divided into three
groups:
Local symptoms: unusual swelling
(tumor in Latin means swelling), hemorrhage (bleeding), ulceration
or jaundice.
Symptoms of metastasis (spreading):
enlarged lymph nodes, cough and hemoptysis, hepatomegaly (enlarged
liver), bone pain, fracture of affected bones and neurological symptoms.
Systemic symptoms: weight loss, poor
appetite and cachexia, excessive sweating (night sweats), anemia,
and specific paraneoplastic phenomena , i.e. specific conditions that
are due to an active cancer, such as thrombosis or hormonal changes.
Every single item in the above list has a substantial
differential diagnosis (it may be associated with unrelated diseases).
Often, cancer is an unexpected finding during investigation for much
more common symptoms, while others are diagnosed through screening
(see below).
Types of Cancer
Cancers originate within a single cell. Hence, cancers
can be classified by the type of cell in which it originates and by
the location of the cell.
Carcinomas originate in epithelial cells, e.g. skin,
digestive tract or glands. Leukemia starts in the bone marrow stem
cells. Lymphoma is a cancer originating in lymphatic tissue. Melanoma
arises in melanocytes. Sarcoma begins in the connective tissue of
bone or muscle. Teratoma begins within germ cells.
Adult Cancers
Adult cancers usually form in epithelial tissues and
are believed often to be the result of a long biological process related
to the interaction of exogenous exposures with genetic and other endogenous
characteristics among susceptible people.
Examples include: bladder carcinoma, blood (and bone
marrow) - hematological malignancies, leukemia, lymphoma, Hodgkin's
disease, non-Hodgkin's lymphoma, multiple myeloma, brain tumor, breast
cancer, cervical cancer, colorectal cancer - in the colon, rectum,
anus, or appendix, esophageal cancer, endometrial cancer - in the
uterus, hepatocellular carcinoma - in the liver, gastrointestinal
stromal tumor (GIST), laryngeal cancer, lung cancer, mesothelioma
- in the pleura or pericardium, oral cancer, osteosarcoma - in bones,
ovarian cancer, pancreatic cancer, prostate cancer, renal cell carcinoma
- in the kidneys, rhabdomyosarcoma - in muscles, skin cancer (including
benign moles and dysplastic nevi), stomach cancer, testicular cancer,
and thyroid cancer.
Cancer can also occur in young children, particularly
infants. Here, the aberrant genetic processes that fail to safeguard
against the clonal proliferation of cells with unregulated growth
potential occur very early in life and progress very quickly.
The age of peak incidence of cancer in children occurs
during the first year of life. Neuroblastoma is the most common infant
malignancy, followed by the leukemias and the central nervous system
cancers. Female infants and male infants have essentially the same
overall cancer incidence rates, but white infants have substantially
higher cancer rates than black infants for most cancer types.
Relative survival for infants is very good for neuroblastoma,
Wilms' tumor and retinoblastoma, but not for most other types of cancer.
Childhood cancers include, from most frequently occurring to least:
Neuroblastoma, leukemia, central nervous system, retinoblastoma, Wilms'
tumor, germ cell, soft tissue sarcomas, hepatic, lymphomas, epithelial.
Diagnosing Cancer
Biopsy
A biopsy leads to the definitive diagnosis of most
malignancies. It requires the removal of cells and/or pieces of tissue
for examination by a pathologist. The tissue diagnosis indicates the
type of cell that is proliferating, its severity (degree of dysplasia),
its extent and size, and - sometimes with help from cytogenetics and
immunohistochemistry - prognostic and therapeutic determinants.
Biopsy can be curative if the whole lesion is removed;
in this case, the borders of the sample are examined closely to see
if all malignant tissue has truly been excised.
The nature of the biopsy depends on the organ that
is sampled. Many biopsies (such as those of the skin, breast or liver)
can happen on an outpatient basis. Biopsies of other organs are performed
under anesthesia and require surgery.
Screening
Cancer screening is the widespread uses of tests to
detect cancers in the population. It is often an inexpensive, noninvasive
procedure. If signs of cancer are detected, more definitive and invasive
followup tests are performed to confirm the diagnosis.
Screening for cancer can lead to earlier diagnosis.
Early diagnosis may lead to extended life. A number of different screening
tests have been developed. Colon cancer can be detected through fecal
occult blood testing and colonoscopy, which reduces both colon cancer
incidence and mortality, presumably through the detection and removal
of precancerous polyps.
Similarly, cervical cytology testing (using the Pap
smear) leads to the identification and excision of precancerous lesions.
Over time, such testing has been followed by a dramatic reduction
of cervical cancer incidence and mortality.
Breast cancers can be detected by breast self-examination
and regular screening mammograms. Testicular self-examination –
is recommended for men from the age of 15 years to detect testicular
cancer. Prostate cancer can be screened for by a digital rectal exam
along with annual prostate specific antigen blood testing.
Screening for cancer is controversial in cases when
it is not yet known if this test actually saves lives. The controversy
arises when it is not clear if the benefits of screening outweigh
the risks of follow-up diagnostic tests and cancer treatments.
For example: when screening for prostate cancer, the
PSA test may detect small cancers that would never become life threatening,
but once detected will lead to treatment. This situation, called overdiagnosis,
puts men at risk for complications from unnecessary treatment such
as surgery or radiation.
Followup procedures used to diagnose prostate cancer
(prostate biopsy) may cause side effects, including bleeding and infection.
Prostate cancer treatment may cause incontinence (inability to control
urine flow) and erectile dysfunction (erections inadequate for intercourse).
For these reasons, it is important that the benefits
and risks of diagnostic procedures and treatment be taken into account
when considering whether to undertake cancer screening.
Use of medical imaging to search for cancer in people
without clear symptoms is similarly marred with problems. There is
a significant risk of detection of an incidentaloma - a benign lesion
that may be interpreted as a malignancy and be subjected to potentially
dangerous investigations.
Source: Wikipedia
