Radiation Therapy (NCI, n.d.)

High dose radiation such as x-rays, gamma rays, electron beams, or protons, kill cancer cells by disrupting the cell’s DNA. Effects of radiation may take days or weeks.
 
Indications for radiation:

• Cure or shrink cancer

• Slow cancer growth
• Prevent recurrence
• Ease cancer symptoms (palliative treatment)

Radiation may be used alone or with other treatments such as surgery, chemotherapy and immunotherapy. In combination with surgery, the timing of radiation is an important part of treatment Before surgery, radiation may shrink the size of the tumor so it can be removed by surgery. During surgery, radiation is directed to the tumor avoiding normal tissue. After surgery, radiation is used to kill cancer cells that were not removed during surgery.
 
Two types of radiation:

• External beam radiation therapy – localized treatment to a specific area of the body usually performed on an outpatient basis
• Internal radiation therapy – radiation is placed within the body in solid forms such as seeds, ribbons, or capsules (brachytherapy) or administered systemically in liquid form, intravenous (IV) or via injection. The radiation travels within the body to all tissues. Body fluids such as urine, sweat, and saliva will give off radiation for some time after treatment.

Chemotherapy (American Cancer Society, 2019b; NCI, n.d.)                                                    

Chemotherapy is a systemic treatment that stops or slows the growth of cancer cells that have metastasized to parts of the body far from the primary tumor.
 
Goals of chemotherapy:

• Curative
• Control growth and prevent metastasis
• Palliative

Chemotherapy is also often used in combination with other therapies as neoadjuvant chemotherapy (to shrink tumors before surgery or radiation) or as adjuvant chemotherapy (to kill cancer cells that were not removed with surgery or radiation).
 
Routes of administration for chemotherapy:

• Oral – pills, capsules, liquids
• IV
• Injection – intramuscular or subcutaneous
• Intrathecal – injection into spinal canal or subarachnoid space into the cerebrospinal fluid (CSF)
• Intraperitoneal (IP) – administered directly into the peritoneal cavity
• Intra-arterial (IA) – injected directly into the artery
• Topical – application of cream onto the skin

Dosing may be calculated based on weight or body surface area and will be affected by age (reduce dose for elderly), nutritional status, obesity, concurrent medications, radiation therapy, blood cell counts, liver or kidney disease.

Targeted Therapy (NCI, 2021)

Targeted therapies are substances developed to inhibit cancer by impeding certain molecules (“targets”) that help cancer grow and spread. Also known as “molecularly targeted drugs,” “molecularly targeted therapies,” and “precision medicine,” these drugs differ from chemotherapy in that they attack specific molecules or proteins while chemotherapies affect both cancer cells and rapidly dividing normal cells. The treatments are either small-molecule drugs or monoclonal antibodies (therapeutic antibodies) that work using a variety of mechanisms:

• Help the immune system destroy cancer cells
• Impede chemical signals that cause cancer cell growth
• Prevent the formation of new blood vessels that supply cancer cells
• Deliver toxic substances to kill cancer cells
• Alter proteins in cancer cells resulting in cell death
• Starve cancer of the hormones it needs to grow

Biomarker Testing for Cancer Treatment (National Cancer Institute, 2021)

Biomarker testing assesses for genes, proteins, and other substances within the tumor or blood that might be susceptible to specific therapies. Some cancer treatments, including targeted therapies and immunotherapies, may only work for people whose cancers have certain biomarkers. Biomarker testing is also known as tumor testing, tumor genetic testing, genomic testing or genomic profiling, molecular testing or molecular profiling, somatic testing, or tumor subtyping.

Types of Targeted Treatments

Hormone Therapy (NCI, 2021)
Hormone therapy is used primarily to treat cancers that depend on hormones to grow, such as prostate, breast, ovarian, and uterine cancers. Hormone therapy can be administered orally or by injection (subcutaneous or intramuscular) and may involve surgery to remove hormone-producing organs (i.e., ovaries in women or testicles in men).
There are two types of hormone therapy:

• Block hormone production
• Interfere with hormone effects

Like chemotherapy, hormone therapy is also often used in combination with other therapies as neoadjuvant or adjuvant treatment and can also be used to treat cancer that returns or spreads to other parts of the body. Common side effects of hormone therapy include hot flashes, loss of interest or inability to have intercourse, nausea, diarrhea, fatigue, and mood changes.

Immunotherapy (American Cancer Society, 2019c; NCI, 2021)
Immunotherapy uses an individual’s immune system to fight cancer either by stimulating the immune cells to work more effectively against cancer cells or by providing synthetic proteins that support the immune system. Also known as biologic therapy or biotherapy, these medications are administered by IV, oral, topical or intravesical (directly into the bladder) routes.

Signal Transduction Inhibitors (NCI, 2021)
Signal transduction inhibitors impede molecules that help cells react to signals from the environment. Cancer cells are stimulated to divide unceasingly without signals from external growth factors. Signal transduction inhibitors prevent this inappropriate signaling.

Gene Expression Modulators (NCI, 2021)
Cancer may develop from a gene that does not normally express in a cell; rather it mutates causing uncontrolled cell growth. Gene expression modulators change the way proteins participate in gene expression.

Apoptosis Inducers
Apoptosis is a process the body uses to get rid of nonessential or abnormal cells through programmed cell death. Some cancer cells can evade this mechanism. Apoptosis inducers provoke cancer cells to self-destruct.

Angiogenesis Inhibitors
Angiogenesis inhibitors target molecules that stimulate new blood vessel formation to tumors thus preventing further growth.

Monoclonal Antibodies
Monoclonal antibodies, created in the lab, deliver toxic substances (radioactive or poisonous chemical) causing cancer cell death. The toxin will not impact normal cells (cells lacking the antibody target).

Stem Cell Transplant (American Cancer Society, 2020)

Stem cell transplants (peripheral blood, bone marrow, and cord blood transplants) are used to treat patients with leukemia, lymphoma, neuroblastoma and multiple myeloma. This therapy replaces the stem cell components (white blood cells, red blood cells, platelets) within the bone marrow that may have been destroyed by cancer, chemotherapy, or radiation. Transplants can be autologous (donated by the patient), allogeneic (donated from another person), or syngeneic (stem cells that come from an identical twin).

In most cases, stem cell transplants do not fight cancer but instead help the body recover from the effects of chemotherapy and radiation. In some cases, allogeneic stem cell transplants may have a graft-versus-tumor effect causing white blood cells from the donor to attack cancer cells. However, allogeneic transplants may also cause graft-versus-host disease in which white blood cells from the donor attack the recipient’s normal cells. This may damage the skin, liver, intestines and other organs. Graft-versus-host disease can be treated with steroids or other immunosuppressant drugs. Other side effects include bleeding and increased risk of infection.