Viral oncology

DEFINITION: Viral oncology is the study of cancers caused by viruses and other such infectious agents.

Cancers treated: Cancers known to be associated with viral agents, including cervical carcinoma, hepatocarcinoma, nasopharyngeal carcinoma, and several forms of lymphoma

Subspecialties: Retrovirology

Training and certification: Viral oncology represents a discipline within the general area of medical oncology, the study of cancer. Although a small proportion of cancers may be directly caused by infectious agents, particularly viruses, most oncologists associated with the medical aspects of the disease are involved with the diagnosis and treatment of cancer rather than the study of the molecular basis of the disease. This is true for most physicians specializing in branches of oncology. Those physicians who practice medical oncology and conduct research in viral oncology are generally associated with medical schools that allow for research and study of the disease, diagnosis, and treatment. These individuals divide their time between seeing patients and directing a laboratory that includes technicians and postdoctoral trainees.

Viral oncology primarily involves researching the molecular changes produced by viral infections that transform normal cells into malignant ones. Training may involve medical school, the outcome of which is a medical degree, or research, which may result in a doctoral degree. Although postdoctoral training is not required, most people with doctorates in the sciences and an interest in cancer research, viral or otherwise, generally pursue additional training after receiving their degrees.

Many universities and medical schools, supported by various federal grants and fellowships, provide specialized training in the field of viral oncology. Generally, these postdoctoral programs require a medical or doctoral degree. In these two- to three-year programs, the individual studies and conducts research with highly regarded individuals in the field. Training may be in a wide range of specialties, including studying tumor viruses, pathogenesis following infection by these viruses, and regulating cell processes affected by such viruses. Those who complete such programs frequently move on to jobs at universities or medical schools, specializing in aspects of medical oncology.

Services and procedures performed: The primary concerns of physicians who deal with cancer are identifying the form, staging, treatment, and prognosis of cancer. Approximately 15 to 20 percent of cancers are associated with infections by viruses and other agents. Viral oncologists study cancers caused by viruses to understand the underlying molecular mechanisms that result in the initial transformation of a cell from a normal, properly regulated entity to one that progressively evolves into a malignant cell. They also develop therapeutic strategies to control the disease or prevent the transformation of normal cells into malignant ones. Viral oncologists may study samples obtained from cancerous tissue to determine the virus's presence or possible role. Generally, however, they are not involved in treating the disease.

The work carried out by viral oncologists depends on the interests of the individual. Some viruses leave “footprints” in the cell following infection. The presence of viral genetic material and the products protein or ribonucleic acid (RNA) encoded by the virus. The researcher may use biopsy material or other cancerous tissue samples to analyze viral information or evidence of viral expression. The results of such analysis may provide clues as to the mechanism of malignant transformation. Clues into the cause of the disease may provide ideas for research into treatment.

Treatment of virus-induced cancers may also involve clinical trials, in which pharmaceuticals may be studied to determine their efficacies. Most such studies involve cooperation between hospitals and pharmaceutical companies.

Related specialties and subspecialties: Viral oncologists specialize in the specific forms of cancers that may follow certain viral infections. Human papillomaviruses (HPV), associated in the minds of many with warts, have also been shown to be the etiological agents behind the development of cervical carcinomas. The study of these deoxyribonucleic acid (DNA)-containing viruses and the mechanism by which they initiate cancer represents a field of active investigation among some virologists.

Retroviruses are a subclass of viruses that contain a genome consisting of RNA. These are relatively simple viruses that encode a relatively small number of genes, often as few as four to five, one of which is considered an oncogene, a gene that, when unregulated, may convert a normal cell into a malignant one. These viruses also encode an enzyme called an RNA-directed DNA polymerase, more commonly called a reverse transcriptase, which copies the RNA genome into DNA. The DNA copy then integrates into the host genome. Such viruses are frequently called RNA tumor viruses. Retrovirologists are viral oncologists who study such viruses, their genome makeup, and the mechanisms by which their encoded oncogene may disrupt cell regulation. Like most viral oncologists, retrovirologists are primarily concerned with the mechanism of malignant transformation rather than treating patients.

A subclass of retroviruses includes agents such as hepatitis B virus (HBV), associated with certain forms of viral hepatitis, but which may also serve as the etiological agent for hepatocarcinoma, cancer of the liver. HBV is a DNA virus that replicates through an RNA intermediary. HBV is also the subject of extensive study by retrovirologists who are interested in this unusual form of replication. Some universities and medical schools provide specialized programs in this area. For example, because hepatitis B infection often results in a lifelong chronic infection, viral oncologists may specialize in the study of the disease and the maintenance of quality care for the patient and education of the patient’s family.

Some forms of lymphomas and leukemias, including T-lymphocyte leukemia, also appear to result from viral infections. Evidence suggests Hodgkin's disease may be the result of viral infection. Certain non-Hodgkin lymphomas are known to be associated with infection. For example, Burkitt lymphoma and nasopharyngeal carcinoma result from infection by a herpesvirus called the Epstein-Barr virus, which is most commonly associated with infectious mononucleosis. Subspecialties in the field of viral oncology exist to study these diseases as well.

Bibliography

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