Cancer

Also Known As: Malignancy, Malignant tumor

Cancer is a disease in which cells in a part of the body become abnormal and grow uncontrollably. Cancerous cells do not go through the natural stages of growth, division, and dying that normal cells do. They multiply unchecked and may form one or more masses of cells (tumors). Tumors can damage healthy tissue and grow large enough to interfere with body functions. However, not all cancers form tumors (e.g., leukemia) and not all tumors are malignant - some are benign (non-cancerous and non-spreading)

Cancer can eventually spread (metastasize) beyond the site of origin into nearby lymph nodes, tissues, and other organs. There are many types of cancer and they are often named according to location in the body where they originate.

Various lab tests are used in the screening, diagnosis, and management as well as the risk assessment of cancer. However, not all types of tests are available for all types of cancer. Below are listed some examples of these types of tests:

  • Risk assessment - determining whether an individual has a high risk for a particular type of cancer; examples include BRCA mutation for breast and ovarian cancer risk and HPV for cervical cancer risk
  • Screening - detecting cancer before symptoms appear; examples include Pap test for cervical cancer
  • Diagnosis - examples include BCR/ABL mutation to help diagnose chronic myelogenous leukemia (CML) or a type of acute lymphoblastic leukemia
  • Treatment - helping to guide the selection of drugs to treat cancer or monitoring effectiveness of treatment; example include HER2/neu to determine whether a woman's breast cancer will respond to the drug trastuzumab and BCR/ABL to monitor treatment of leukemia

Tests

The goals of breast cancer testing are to:

  • Identify genetic risk in high-risk women
  • Detect and diagnose breast cancer in its earliest stages
  • Determine how far it has spread
  • Evaluate the cancer's characteristics in order to guide treatment
  • Monitor the effectiveness of treatment and monitor the person over time to detect and address any cancer recurrences

The table below summarizes various breast cancer tests. The tissue samples required for some of the tests may involve a needle biopsy, in which cells from the breast are aspirated through a needle into a syringe, or by surgically removing some breast tissue or a tumor (open biopsy). Detailed discussions of the tests follow the table.

Tests for Breast Cancer

TEST DESCRIPTION TEST SAMPLE
Mammogram Highly-sensitive digital X-ray technology that may detect small lumps that otherwise would not be detected through self-exam. N/A
BRCA1 / BRCA2 Genetic mutations, if present, suggest a likelihood of breast cancer occurrence as high as 80%. Blood
HER2/neu A test for the overexpression of HER2 proteins or the amplification of the gene that codes for the protein; tumors that are positive may respond well to a medication that targets HER2, such as Herceptin. Tissue
HER2 (blood) After an initial diagnosis of metastatic breast cancer is made, this blood test may be performed and, if the initial level is greater than 15 ng/mL, the test may be used to monitor treatment. Blood
Estrogen Receptor/
Progesterone Receptor
Increased levels suggest a good response to hormonal therapy. Hormonal therapy is not the same as hormone replacement therapy (HRT) and presence of these receptors does not indicate that HRT caused the cancer. Tissue
CA15-3/ CA27.29 This test measures a specific cancer antigen. Elevated blood levels may indicate recurrence of cancer. Blood
OncotypeDX A genetic test that may assist in determining risk of recurrence and predict who will benefit from hormone therapy or chemotherapy. Tissue
MammaPrint A genetic test that may assist in determining whether a woman is at risk of recurrence of cancer, to help guide treatment. Tissue

What is leukemia?

Leukemia is cancer of the blood and bone marrow. It develops when bone marrow, which produces blood cells, forms abnormal white blood cells that divide out of control. Normal white blood cells are the body's infection fighters, but these abnormal white blood cells, called leukemia cells, don't die at the same rate as normal blood cells. Instead, they accumulate and crowd out normal cells, like red blood cells, platelets, and normal white blood cells and their precursors, in the bone marrow. This can lead to difficulty getting enough oxygen to tissues (anemia), excess bleeding, and repeated infections.

Over time, leukemia cells can spread through the bone marrow and bloodstream, where they continue to divide, sometimes forming tumors and damaging organs. The organs affected depend on the type of leukemia. For example, the spleen, liver, and lymph nodes may become enlarged and swollen with the abnormal cells. Sometimes, leukemia cells reach the central nervous system (the brain and spinal cord) and build up in the cerebrospinal fluid.

Tests

Laboratory Tests
A number of laboratory tests may be used to help diagnose leukemia, determine the type, and monitor the effectiveness of treatment. After successful treatment (remission), testing may be use to monitor for recurrence of disease.

Blood tests:

  • Complete blood count (CBC) and WBC differential. These routine tests are ordered to count the number, maturity, and proportion of different types of cells in the blood. These tests can provide the first evidence of leukemia, and they are often the first tests ordered to diagnose leukemia. Irregularities in cell counts, such as elevated white blood cell counts or low red blood cell counts, may be due to leukemia or to a variety of temporary or chronic conditions. But blasts (immature blood cell precursors) are not normally seen in the blood, so if they are present, some kind of leukemia is likely and follow-up testing will be ordered. The CBC and differential are also important tools to monitor the effectiveness of treatment and to detect disease recurrence.
  • Blood smear. A blood smear, or peripheral blood smear, is often used to follow up a CBC with abnormal white blood cells, red blood cells or platelets, or with unclear results. A drop of blood is smeared on a microscope slide and examined for immature cells or cells with abnormal sizes, shapes or appearance compared to normal cell

Other tests:

  • Bone marrow aspiration/biopsy. Bone marrow is a matrix of fibrous supporting tissue, fluid ("liquid marrow"), undifferentiated stem cells, and a mixture of blasts, maturing and mature blood cells. If a health practitioner suspects that someone has leukemia, a bone marrow aspiration and/or biopsy procedure will be done to look at the fluid and/or tissue in the marrow. In an aspiration, a bone marrow sample is collected from the hipbone, or sometimes the sternum in adults, or the shinbone in infants. A pathologist or other specialist then examines the marrow sample (bone and/or fluid) under the microscope, evaluating the number, size, and appearance of each of the cell types as well as the proportions of mature and immature cells. If leukemia is present, the type and severity of the disease can be determined. This test will also help establish a baseline for bone marrow cells, to see how they respond to treatment.
  • Spinal tap (lumbar puncture) and cerebrospinal fluid analysis. If leukemia is found in the bone marrow, a spinal tap may also be done to look for leukemia cells in the cerebrospinal fluid (CSF). If leukemic cells are seen in the CSF, additional treatment (for example, direct injection of drug into the CSF space) may be necessary.
  • Immunophenotyping or phenotyping by flow cytometry. This test can be used to help diagnose leukemia and to determine which type of leukemia a person has. Cells from the blood, bone marrow, or lymph nodes are incubated with commercially generated antibodies, which selectively bind to antigens on the surface of leukemia cells or in their cytoplasm. The antigens act like markers and are detected by flow cytometry, a type of test that uses a laser beam and a computer to identify cells types based on the antigens present. This process is known as immunophenotyping and helps to categorize the type of leukemia present.
  • Cytogenetic tests (FISH and karyotyping). Cytogenetic tests look at chromosome structure and number. They are used to find abnormal chromosomes associated with leukemias, other cancers, and genetic disorders. They help diagnosis and differentiate leukemias by detecting translocations (where part of a chromosome breaks and reattaches to a different chromosome) for certain acute myeloid leukemias, acute promyelocytic leukemias, chronic myelocytic leukemias, and acute lymphoblastic leukemias, among others. These techniques can also detect deletions associated with acute myeloid leukemia or myelodysplastic syndromes and increases or decreases in the number of chromosomes, such as trisomies (trisomy 12) for chronic lymphocytic leukemia.
  • Chromosome analysis (karyotyping) is a cytogenetic test that maps the 46 chromosomes in cells to look for changes in arrangement, size, or number (including deletions or translocations) that are associated with leukemia.
  • Fluorescent in situ hybridization (FISH) is a cytogenetic test that looks for changes in chromosomes that come from genetic variations. It is generally more sensitive than karyotyping. In FISH, an abnormal gene segment in a chromosome is made to "light up" or fluoresce when it is bound by a special probe. FISH helps diagnose different leukemias that may look similar but have different genetic abnormalities and therefore may require different treatment. For more on this, see the article The Universe of Genetic Testing: Cytogenetics (Chromosome Analysis).
  • Polymerase chain reaction (PCR). One factor that contributes to the uncontrolled growth of cancer cells is malfunctioning proteins that control cell growth and development. Those malfunctions can result from abnormalities in DNA from mutations, inversions, fusions, or deletions of parts of the genetic code. The polymerase chain reaction is a laboratory method that amplifies DNA to detect those abnormalities associated with certain types of leukemia. PCR tests can help guide the type or intensity of treatment and/or determine prognosis for a certain leukemia and sometimes identify the target for therapy (targeted therapy) based on the genetic makeup of the cancer cells. Some common PCR tests and their associated leukemia types are:
    • Acute promyelocytic leukemia [PML-RARA ]
    • Acute myeloid leukemia [AML1-ETO, CBFB-MYH11, NPM1 mutation, CEBPA mutation, FLT3 mutation]
    • Acute lymphoblastic leukemia [TEL-AML1, IL3-IGH, BCR-ABL]
    • Myeloid proliferative neoplasm with eosinophilia [FlP1L1-PDGFRA ]
    • Chronic myelogenous leukemia [BCR-ABL ]
    There are also other PCR tests that are used less frequently. Minimum residual disease (MRD) tests. These are relatively new, more sensitive flow cytometry or PCR-based tests to detect very small amounts of leukemic cells post-treatment, known as minimum residual disease (MRD). This can help guide treatment and prevent relapses after the leukemia has gone into remission.

What is cervical cancer?

Cervical cancer is caused by the uncontrolled growth of cells in the cervix. The cervix is the narrowed bottom portion of a woman's uterus. Shaped like a cone, it connects the uterus to the vagina.

The vast majority of cervical cancers are caused by persistent infections with certain types of human papillomavirus (HPV). HPV is a very common sexually transmitted disease. While nearly all cervical cancers are caused by HPV, not all HPV strains cause cervical cancer. Those that cause cervical cancer are considered high-risk types.

Cervical cancer begins slowly. The earliest, precancerous changes cause the cells lining the inside or outside of the cervix to appear different from normal cervical cells. These atypical, precancerous cells are more likely to progress to cancer if left untreated. If the cells become cancerous, they are initially limited to the surface lining (in situ). Without treatment, the cancer cells can become invasive by growing into the supporting tissues of the cervix and can potentially spread to other body sites.

There are two primary types of cervical cancer. Squamous cell carcinomas, which occur in the flat squamous cells that cover the outside of the cervix, are the most common. They make up about 80-90% of cervical cancers. Most other cases are adenocarcinomas, rising from mucus-producing gland cells of the opening of the cervix (the endocervix). A few cervical cancers are mixtures of both types.

With early detection, cervical cancer is usually treatable by surgically removing the cancer. If early stage cancer has spread beyond the surface of the cervix, treatment may require a hysterectomy, radiation, or chemotherapy. Early treatment cures about 85-90% of women with cervical cancer. Given time, cervical cancer can spread (metastasize) to the rest of the uterus, the bladder, the rectum, and the abdominal wall. Eventually, it can reach the pelvic lymph nodes and metastasize further, invading other organs throughout the body. Cure rates decline as cervical cancer spreads, with extensive cervical cancer usually becoming fatal.

Tests

Screening tests

  • Pap test: the Papanicolaou (Pap) test is widely used to screen for precancerous or cancerous changes in cervical cells. The earliest, precancerous changes cause the cells lining the inside or outside of the cervix to appear different from normal cervical cells. These changes, when present on a Pap test, are termed "atypical cells." Atypical cells are not entirely specific for a precancerous condition, however, and can temporarily appear in response to infections or irritation of the cervix lining. Precancerous cells can become more abnormal in appearance over time and are more likely to progress to cancer if left untreated. In Pap tests, these more abnormal (intermediate) cellular changes are called low-grade or high-grade squamous intraepithelial lesions [see the sidebar on Pap test terminology].
  • HPV DNA test: There are multiple DNA tests that can detect human papillomavirus (HPV) infections before cell abnormalities are evident, according to the National Cancer Institute. These tests work by screening for the DNA of different types of high-risk HPV in cervical cells. Some HPV DNA tests detect high-risk HPV without identifying the specific type of HPV. Others detect specific HPV types known to cause most HPV-related cancers.

What is prostate cancer?

Prostate cancer is the uncontrolled growth of cells in the prostate, a small, walnut-shaped gland that encircles the upper urethra in men and produces a fluid that makes up part of semen. The prostate gland consists of several types of cells, but almost all prostate cancers begin in the cells that produce the prostate fluid (gland cells). These cancers are called adenocarcinomas. .

Prostate cancer is the most common cancer in men after skin cancer. According to the American Cancer Society, about 220,800 new cases of prostate cancer will be diagnosed in the United States in 2015 and as many as 27,540 men will die of it. .

The risk of developing prostate cancer varies with ethnicity, with African American men at the highest risk. Risk is also elevated in men with a family history of the disease and increases in general as men age. More than 60% of all prostate cancers are diagnosed in men over the age of 65. .

Tests

Laboratory Testing.

Laboratory testing may be used to screen asymptomatic and symptomatic men for prostate cancer, rule out other diseases and conditions that may be causing or worsening a person's symptoms, monitor the effectiveness of treatment for cancer, and monitor for recurrence.

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