treatment of cancer treatment of cancer cancer can be treated by surgery, chemotherapy, radiation therapy, hormonal therapy, targeted therapy (including immunotherapy such as monoclonal antibody therapy) and synthetic lethality, most commonly as a series of separate treatments (e.g. chemotherapy before surgery). the choice of therapy depends upon the location and grade of the tumor and the stage of the disease, as well as the general state of the patient (performance status). cancer genome sequencing helps in determining which cancer the patient exactly has for determining the best therapy for the cancer. a number of experimental cancer treatments are also under development. under current estimates, two in five people will have cancer at some point in their lifetime. treatment of cancera patient prepared for radiation therapy.specialtyoncologyicd-10-pcs110000053 complete removal of the cancer without damage to the rest of the body (that is, achieving cure with near-zero adverse effects) is the ideal, if rarely achieved, goal of treatment and is often the goal in practice. sometimes this can be accomplished by surgery, but the propensity of cancers to invade adjacent tissue or to spread to distant sites by microscopic metastasis often limits its effectiveness; and chemotherapy and radiotherapy can have a negative effect on normal cells. therefore, cure with nonnegligible adverse effects may be accepted as a practical goal in some cases; and besides curative intent, practical goals of therapy can also include (1) suppressing the cancer to a subclinical state and maintaining that state for years of good quality of life (that is, treating the cancer as a chronic disease), and (2) palliative care without curative intent (for advanced-stage metastatic cancers). because "cancer" refers to a class of diseases, it is unlikely that there will ever be a single "cure for cancer" any more than there will be a single treatment for all infectious diseases. angiogenesis inhibitors were once thought to have potential as a "silver bullet" treatment applicable to many types of cancer, but this has not been the case in practice. types of treatments the treatment of cancer has undergone evolutionary changes as understanding of the underlying biological processes has increased. tumor removal surgeries have been documented in ancient egypt, hormone therapy and radiation therapy were developed in the late 19th century. chemotherapy, immunotherapy and newer targeted therapies are products of the 20th century. as new information about the biology of cancer emerges, treatments will be developed and modified to increase effectiveness, precision, survivability, and quality of life. surgery in theory, non-hematological cancers can be cured if entirely removed by surgery, but this is not always possible. when the cancer has metastasized to other sites, especially if the metastases are to sites far away from the original tumor (in other words, distant metastases, rather than local or regional ones) in the body prior to surgery, complete surgical excision is usually impossible. in the halstedian model of cancer progression, tumors grow locally, then spread to the lymph nodes, then to the rest of the body. this has given rise to the popularity of local-only treatments such as surgery for small cancers. even small localized tumors are increasingly recognized as possessing metastatic potential. examples of surgical procedures for cancer include mastectomy for breast cancer, prostatectomy for prostate cancer, and lung cancer surgery for non-small cell lung cancer. the goal of the surgery can be either the removal of only the tumor, or the entire organ. a single cancer cell is invisible to the naked eye but can regrow into a new tumor, a process called recurrence. for this reason, the pathologist will examine the surgical specimen to determine if a margin of healthy tissue is present, thus decreasing the chance that microscopic cancer cells are left in the patient. in addition to removal of the primary tumor, surgery is often necessary for staging, e.g. determining the extent of the disease and whether it has metastasized to regional lymph nodes. staging is a major determinant of prognosis and of the need for adjuvant therapy. occasionally, surgery is necessary to control symptoms, such as spinal cord compression or bowel obstruction. this is referred to as palliative treatment. surgery may be performed before or after other forms of treatment. treatment before surgery is often described as neoadjuvant. in breast cancer, the survival rate of patients who receive neoadjuvant chemotherapy are no different from those who are treated following surgery. giving chemotherapy earlier allows oncologists to evaluate the effectiveness of the therapy, and may make removal of the tumor easier. however, the survival advantages of neoadjuvant treatment in lung cancer are less clear. radiation therapy main article: radiation therapy radiation therapy (also called radiotherapy, x-ray therapy, or irradiation) is the use of ionizing radiation to kill cancer cells and shrink tumors by damaging their dna (the molecules inside cells that carry genetic information and pass it from one generation to the next), making it impossible for these cells to continue to grow and divide. radiation therapy can either damage dna directly or create charged particles (free radicals) within the cells that can in turn damage the dna. radiation therapy can be administered externally via external beam radiotherapy (ebrt) or internally via brachytherapy. the effects of radiation therapy are localised and confined to the region being treated. although radiation damages both cancer cells and normal cells, most normal cells can recover from the effects of radiation and function properly. the goal of radiation therapy is to damage as many cancer cells as possible, while limiting harm to nearby healthy tissue. hence, it is given in many fractions, allowing healthy tissue to recover between fractions. radiation therapy may be used to treat almost every type of solid tumor, including cancers of the brain, breast, cervix, larynx, liver, lung, pancreas, prostate, skin, stomach, uterus, or soft tissue sarcomas. radiation is also used to treat leukemia and lymphoma. radiation dose to each site depends on a number of factors, including the radio sensitivity of each cancer type and whether there are tissues and organs nearby that may be damaged by radiation. thus, as with every form of treatment, radiation therapy is not without its side effects. radiation therapy can lead to dry mouth from exposure of salivary glands to radiation, resulting in decreased saliva secretion. post therapy, the salivary glands will resume functioning but rarely in the same fashion. dry mouth caused by radiation can be a lifelong problem. radiation might not be a choice of treatment if the tumour was diagnosed in late stages or is in a vulnerable location, as radiation might be more likely to cause damage to organs at effective doses. moreover, radiation therapy for patients under 14 can cause particularly significant long-term side effects, such as hearing loss and blindness, that influence the lifestyle of the young patients. children who had received cranial radiotherapy are deemed at a high risk for academic failure and cognitive delay. a study by reddy a.t. determined the significant decrease in iq with higher doses of radiation, specifically for children with brain tumours. alternative treatments, such as surgical resection, may be used in young patients to decrease the occurrence of side effects. chemotherapy main article: chemotherapy chemotherapy is the treatment of cancer with drugs ("anticancer drugs") that can destroy cancer cells. chemotherapy can be given in a variety of ways such as injections into the muscles, skin, artery, or vein, or it could even be taken by mouth in the form of a pill. in current usage, the term "chemotherapy" usually refers to cytotoxic drugs which affect rapidly dividing cells in general, in contrast with targeted therapy (see below). chemotherapy drugs interfere with cell division in various possible ways, e.g. with the duplication of dna or the separation of newly formed chromosomes. most forms of chemotherapy target all rapidly dividing cells and are not specific to cancer cells, although some degree of specificity may come from the inability of many cancer cells to repair dna damage, while normal cells generally can. hence, chemotherapy has the potential to harm healthy tissue, especially those tissues that have a high replacement rate (e.g. intestinal lining). these cells usually repair themselves after chemotherapy. because some drugs work better together than alone, two or more drugs are often given at the same time. this is called "combination chemotherapy"; most chemotherapy regimens are given in a combination. since chemotherapy affects the whole body, it can have a wide range of side effects. patients often find that they start losing their hair since the drugs that are combatting the cancer cells also attack the cells in the hair roots. this powerful treatment can also lead to fatigue, loss of appetite, and vomiting depending on the person. the treatment of some leukaemias and lymphomas requires the use of high-dose chemotherapy, and total body irradiation (tbi). this treatment ablates the bone marrow, and hence the body's ability to recover and repopulate the blood. for this reason, bone marrow, or peripheral blood stem cell harvesting is carried out before the ablative part of the therapy, to enable "rescue" after the treatment has been given. this is known as autologous stem cell transplantation. targeted therapies main article: targeted therapy targeted therapy, which first became available in the late 1990s, has had a significant impact in the treatment of some types of cancer, and is currently a very active research area. this constitutes the use of agents specific for the deregulated proteins of cancer cells. small molecule targeted therapy drugs are generally inhibitors of enzymatic domains on mutated, overexpressed, or otherwise critical proteins within the cancer cell. prominent examples are the tyrosine kinase inhibitors imatinib (gleevec/glivec) and gefitinib (iressa). monoclonal antibody therapy is another strategy in which the therapeutic agent is an antibody which specifically binds to a protein on the surface of the cancer cells. examples include the anti-her2/neu antibody trastuzumab (herceptin) used in breast cancer, and the anti-cd20 antibody rituximab, used in a variety of b-cell malignancies. targeted therapy can also involve small peptides as "homing devices" which can bind to cell surface receptors or affected extracellular matrix surrounding the tumor. radionuclides which are attached to these peptides (e.g. rgds) eventually kill the cancer cell if the nuclide decays in the vicinity of the cell. especially oligo- or multimers of these binding motifs are of great interest, since this can lead to enhanced tumor specificity and avidity. photodynamic therapy (pdt) is a ternary treatment for cancer involving a photosensitizer, tissue oxygen, and light (often using lasers). pdt can be used as treatment for basal cell carcinoma (bcc) or lung cancer; pdt can also be useful in removing traces of malignant tissue after surgical removal of large tumors. in february 2019, medical scientists announced that iridium attached to albumin, creating a photosensitized molecule, can penetrate cancer cells and, after being irradiated with light, destroy the cancer cells. high-energy therapeutic ultrasound could increase higher-density anti-cancer drug load and nanomedicines to target tumor sites by 20x fold higher than traditional target cancer therapy. targeted therapies under pre-clinical development as potential cancer treatments include morpholino splice switching oligonucleotides, which induce erg exon skipping in prostate cancer models, multitargeted kinase inhibitors that inhibit the pi3k with other pathways including mek and pim, and inhibitors of nf-κb in models of chemotherapy resistance. immunotherapy a renal cell carcinoma (lower left) in a kidney specimen. main article: cancer immunotherapy cancer immunotherapy refers to a diverse set of therapeutic strategies designed to induce the patient's own immune system to fight the tumor. contemporary methods for generating an immune response against tumours include intravesical bcg immunotherapy for superficial bladder cancer, and use of interferons and other cytokines to induce an immune response in renal cell carcinoma and melanoma patients. cancer vaccines to generate specific immune responses are the subject of intensive research for a number of tumours, notably malignant melanoma and renal cell carcinoma. sipuleucel-t is a vaccine-like strategy in late clinical trials for prostate cancer in which dendritic cells from the patient are loaded with prostatic acid phosphatase peptides to induce a specific immune response against prostate-derived cells. allogeneic hematopoietic stem cell transplantation ("bone marrow transplantation" from a genetically non-identical donor) can be considered a form of immunotherapy, since the donor's immune cells will often attack the tumor in a phenomenon known as graft-versus-tumor effect. for this reason, allogeneic hsct leads to a higher cure rate than