Tumor

Neoplastic tumor of the cheek skin, here a benign neoplasm of the sweat glands called Hidradenoma.

A tumor or tumour is the name for a swelling or lesion formed by an abnormal growth of cells (termed neoplastic).^[1] Tumor is not synonymous with cancer. A tumor can be benign, pre-malignant or malignant, whereas cancer is by definition malignant.

Etymology

The term tumor is derived, from the Old French word tumour, and from the Latin term tumor or "swelling". It originally meant an abnormal swelling of the flesh. In contemporary English, tumor is synonymous with solid neoplasm (abnormal proliferation of cells),^[2], while all other forms of swelling are called swelling.^[3] Furthermore, this usage is common in medical literature where the nouns tumefaction and tumescence derived from the adjective tumefied. These nouns are also the current medical terms for non-neoplastic swelling.

Cause

A neoplasm is an abnormal proliferation of tissues, usually caused by genetic mutations. Most neoplasms cause a tumor, with a few exceptions like leukemia or carcinoma in situ. Other causes of tumor development include exposure to chemicals and toxins like benzene, excessive alcohol and tobacco consumption, excessive exposure to sunlight and/or radiation, or an inactive sedentary lifestyle and obesity. Certain viruses can also play a role in the development of tumors, such as cervical cancer (human papillomavirus) and hepatocellular carcinoma (hepatitis B virus).^[4]

Tumors may be benign, pre-malignant or malignant. The nature of the tumor is determined by a pathologist after examination of the tumor tissues from a biopsy or a surgical excision specimen.

Cases of Contagiousness

Main article: CTVT

In the case of Canine Transmissible Venereal Tumor (CTVT), the tumor cells can actually be contagious. CTVT is a tumor found in the domestic dog (Canis familiaris). It has been theorized and now substantiated that the the infectious agent of this cancer is the cancer cell itself, and that the tumor is clonal in origin. In the case of CTVT, the tumor is passed through the population by allograft, with the tumor cells from one animal directly seeding tumor formation in the next, usually during coitus^[5].

Are Tumor Cells Infectious?

Tumor cells are generally not infective to individuals other than the host. The reason behind this is the presence of MHC proteins which are host-specific and help the immune system distinguish between the self and non-self. These proteins are present on the surface of the cells and produces vigorous immune response if a foreign cell is found in the body. However, tumor can be transplanted in an individual if its immune system is compromised. ^[6]

Treatment

Treatment depends on the size and type of the tumor, the initial location of the tumor, and the general health of the person. The goals of treatment may be relief of symptoms, improved comfort or functioning. Tumor treatment also varies based on whether it is in benign or malignant condition. If the malignant tumor is benign (has no potential to spread) and is located in a area where it will not cause any symptoms or disrupt the proper functioning of the organ, most often no treatment is needed. However, benign tumors may be removed for cosmetic reasons.If a tumor is malignant, possible treatments include surgery, chemotherapy, radiation, or a combination of these procedures. If the cancer is confined to only one location, the purpose of treatment is usually surgical removal of the malignant tumor and treatment. In some circumstances, If the malignant tumor has spread only to local lymph nodes, these may also be removed. If all of the cancer cannot be removed with surgery, the options for treatment include radiation and chemotherapy, or combination of these methods. In contrast, lymphoma usually is not treated with surgery and chemotherapy; and radiation therapy may be the possible treatment ^[7].

References

1. ↑ Tumor at Dorland's Medical Dictionary
2. ↑ Tumor in MedlinePlus Medical Encyclopedia
3. ↑ Swelling in MedlinePlus Medical Encyclopedia
4. ↑ The New York Times Health Guide (November29, 2008)doi: http://health.nytimes.com/health/guides/disease/tumor/overview.html
5. ↑ VonHoldt BM, Ostrander EA. The singular history of a canine transmissible tumor. Cell. 2006 Aug 11; 126(3):445-7.
6. ↑ Dingli, D., Nowak, MA. "Cancer Biology: Infectious Tumor Cells". Nature. 2006 Sep. 7. Vol. 443. Pp. 35-6.
7. ↑ http://www1.wfubmc.edu/cancer/Types+of+Cancer/Brain+Tumors/

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