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:
The goals of breast cancer testing are to:
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
|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|
|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.
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.
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.
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. .
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.