Cancer may affect people at all ages, even fetuses, but the risk for most varieties increases with age. Cancer causes about 13% of all deaths. According to the American Cancer Society, 7.6 million people died from cancer in the world during 2007.

Cancer: a malignant neoplasm is a class of diseases in which a group of cells display uncontrolled growth (division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood). These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, and do not invade or metastasize. Most cancers form a tumor but some, like leukemia, do not. The branch of medicine concerned with the study, diagnosis, treatment, and prevention of cancer is oncology.

Cancer may affect people at all ages, even fetuses, but the risk for most varieties increases with age. Cancer causes about 13% of all deaths. According to the American Cancer Society, 7.6 million people died from cancer in the world during 2007.

Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be due to the effects of carcinogens, such as tobacco smoke, radiation, chemicals, or infectious agents. Other cancer-promoting genetic abnormalities may be randomly acquired through errors in DNA replication, or are inherited, and thus present in all cells from birth. The heritability of cancers are usually affected by complex interactions between carcinogens and the host’s genome. New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are increasingly recognized as important.

Genetic abnormalities found in cancer typically affect two general classes of genes. Cancer-promoting oncogenes are typically activated in cancer cells, giving those cells new properties, such as hyperactive growth and division, protection against programmed cell death, loss of respect for normal tissue boundaries, and the ability to become established in diverse tissue environments. Tumor suppressor genes are then inactivated in cancer cells, resulting in the loss of normal functions in those cells, such as accurate DNA replication, control over the cell cycle, orientation and adhesion within tissues, and interaction with protective cells of the immune system.

Diagnosis usually requires the histologic examination of a tissue biopsy specimen by a pathologist, although the initial indication of malignancy can be symptoms or radiographic imaging abnormalities. Most cancers can be treated and some cured, depending on the specific type, location, and stage. Once diagnosed, cancer is usually treated with a combination of surgery, chemotherapy and radiotherapy. As research develops, treatments are becoming more specific for different varieties of cancer. There has been significant progress in the development of targeted therapy drugs that act specifically on detectable molecular abnormalities in certain tumors, and which minimize damage to normal cells. The prognosis of cancer patients is most influenced by the type of cancer, as well as the stage, or extent of the disease. In addition, histologic grading and the presence of specific molecular markers can also be useful in establishing prognosis, as well as in determining individual treatments.


Cancers are classified by the type of cell that resembles the tumor and, therefore, the tissue presumed to be the origin of the tumor. These are the histology and the location, respectively.

Cancer classified in two broad classes is:

Malignant tumours (cancers) are usually named using -carcinoma, -sarcoma or -blastoma as a suffix, with the Latin or Greek word for the organ of origin as the root. For instance, a cancer of the liver is called hepatocarcinoma; a cancer of the fat cells is called liposarcoma. For instance, the most common type of breast cancer is called ductal carcinoma of the breast or mammary ductal carcinoma.

Benign tumours (which are not cancers) are named using -oma as a suffix with the organ name as the root. For instance, a benign tumour of the smooth muscle of the uterus is called leiomyoma (the common name of this frequent tumour is fibroid). Unfortunately, some cancers also use the -oma suffix, examples being melanoma and seminoma.

Types of Cancer

Carcinoma: Malignant tumours derived from epithelial cells. This group represents the most common cancers, including the common forms of breast, prostate, lung and colon cancer.

Sarcoma: Malignant tumors derived from connective tissue, or mesenchymal cells.

Lymphoma and leukaemia: Malignancies derived from hematopoietic (blood-forming) cells

Germ cell tumour: Tumors derived from totipotent cells. In adults most often found in the testicle and ovary; in fetuses, babies, and young children most often found on the body midline, particularly at the tip of the tailbone; in horses most often found at the poll (base of the skull).

Blastic tumour or blastoma: A tumour (usually malignant) which resembles an immature or embryonic tissue. Many of these tumours are most common in children.

Signs and Symptoms

Cancer signs and symptoms can be divided into three groups:

Local symptoms: unusual lumps or swelling (tumour), haemorrhage (bleeding), pain and/or ulceration. Compression of surrounding tissues may cause symptoms such as jaundice (yellowing the eyes and skin).

Symptoms of metastasis (spreading): enlarged lymph nodes, cough and hemoptysis, hepatomegaly (enlarged liver), bone pain, fracture of affected bones and neurological symptoms. Although advanced cancer may cause pain, it is often not the first symptom.

Systemic symptoms: weight loss, poor appetite, fatigue and cachexia (wasting), excessive sweating (night sweats), anaemia and specific paraneoplastic phenomena, i.e. specific conditions that are due to active cancer, such as thrombosis or hormonal changes.

Causes of Cancer

Cancer is a diverse class of diseases which differ widely in their causes and biology. Any organism, even plants, can acquire cancer.
Mutation: chemical carcinogens
Cancer pathogenesis is traceable back to DNA mutations that impact cell growth and metastasis. Substances that cause DNA mutations are known as mutagens, and mutagens that cause cancers are known as carcinogens. Particular substances have been linked to specific types of cancer. Tobacco smoking is associated with many forms of cancer and causes 90% of lung cancer. Prolonged exposure to asbestos fibres is associated with mesothelioma.

Tobacco smoke contains over fifty known carcinogens, including nitrosamines and polycyclic aromatic hydrocarbons. Tobacco is responsible for about one in three of all cancer deaths in the developed world, and about one in five worldwide.

Mutation: ionizing radiation
Sources of ionizing radiation, such as radon gas, can cause cancer. Prolonged exposure to ultraviolet radiation from the sun can lead to melanoma and other skin malignancies.

Non-ionizing radiofrequency radiation from mobile phones and other sources has also been proposed as a cause of cancer, but there is little evidence of such a link. Nevertheless, a few experts caution against prolonged exposure based on the precautionary principle.

Viral or bacterial infection
Some cancers can be caused by infection with pathogens. Many cancers originate from a viral infection; this is especially true in animals such as birds, but also in humans, as viruses are responsible for 15% of human cancers worldwide. The main viruses associated with human cancers are human papillomavirus, hepatitis B and hepatitis C virus, Epstein-Barr virus, and human T-lymphotropic virus.

The mode of virally-induced tumours can be divided into two, acutely-transforming or slowly-transforming. In acutely transforming viruses, the virus carries an overactive oncogene called viral-oncogene (v-onc), and the infected cell is transformed as soon as v-onc is expressed. In contrast, in slowly-transforming viruses, the virus genome is inserted near a proto-oncogene in the host genome. The viral promoter or other transcription regulation elements then cause overexpression of that proto-oncogene. This induces uncontrolled cell division. Because the site of insertion is not specific to proto-oncogenes and the chance of insertion near any proto-oncogene is low, slowly-transforming viruses will cause tumours much longer after infection than the acutely-transforming viruses.

Hormonal imbalances

Some hormones can act in a similar manner to non-mutagenic carcinogens in that they may stimulate excessive cell growth. A well-established example is the role of hyperestrogenic states in promoting endometrial cancer.

Immune system dysfunction
HIV is associated with a number of malignancies, including Kaposi’s sarcoma, non-Hodgkin’s lymphoma, and HPV-associated malignancies such as anal cancer and cervical cancer. AIDS-defining illnesses have long included these diagnoses. The increased incidence of malignancies in HIV patients points to the breakdown of immune surveillance as a possible etiology of cancer. Certain other immune deficiency states (e.g. common variable immunodeficiency and IgA deficiency) are also associated with increased risk of malignancy.

Some Important Websites & Links for Cancer

American Society of Clinical Oncology .Making a world of Difference in Cancer Care.

ESSO is increasingly involved in the training of surgeons concerned by cancer care throughout Europe and in promoting the development of guidelines of good practice in cancer surgery. The Society also seeks to promote knowledge and education about cancer care and to facilitate basic and clinical research in oncology. ESSO publishes a monthly Journal, the European Journal of Surgical Oncology-EJSO and facilitates international exchanges of surgeons specializing in oncology.

A Cancer Journal for Clinicians is a peer-reviewed journal of the American Cancer Society providing cancer care professionals with up-to-date information on all aspects of cancer diagnosis, treatment, and prevention.

The Leading Cancer charity in New South Wales Australia

Advancing Immunology Conquering Cancer

Molecular Cancer, a forum for exciting findings in the field of cancer-related research, is an Open Access journal, providing an unparalleled opportunity to present information to specialists and the public. The online appearance of Molecular Cancer allows the immediate publication of accepted articles and the presentation of large amounts of data and supplemental information.

The Gynecologic Cancer Foundation’s mission is to provide women with knowledge about the risks, prevention, early detection and treatment of gynecologic cancer, and empower them to become the best advocates for their health. The Foundation also funds promising research.

Improving cancer care through dissemination of up-to-date & accurate educational programming and information for health care professionals, cancer patients & their family members.

Cancer Care Ontario is the provincial agency responsible for continually improving cancer services. As the government’s cancer advisor, Cancer Care Ontario works to reduce the number of people diagnosed with cancer and make sure patients receive better care every step of the way.

Save lives by empowering and educating the world’s population through a centralized resource for reliable, current and comprehensible information about the biology and treatment of cancer.

American society of Cancer, join the fight against cancer

Karmanos University carries on research in the field of cancer

Information for those lives are touched by cancer

Welcome to Cancer Research UK, the UK’s leading charity dedicated to cancer research. Our websites have a wealth of information about cancer, our research, how to donate and more ways to support us.

As a leader in nationwide efforts to ease the burden of cancer, CDC works with national cancer organizations, state health agencies, and other key groups to develop, implement, and promote effective strategies for preventing and controlling cancer.

A national, community-based organization of volunteers, whose mission is the eradication of cancer and the enhancement of the quality of life of people living with cancer

WHO joins with the sponsoring International Union against Cancer to promote ways to ease the global burden of cancer. Preventing cancer and raising quality of life for cancer patients are recurring themes.

Cancer Care is a national nonprofit organization that provides free, professional support services for anyone affected by cancer.

The Cancer Project promotes cancer prevention and survival through a better understanding of cancer causes, particularly the link between nutrition and cancer. Through research, education, and advocacy, we are saving lives.

Cancer News on the Net is dedicated to bringing patients and their families the latest news and information on cancer diagnosis, treatment and prevention.

Cancer News on the Net is dedicated to bringing patients and their families Connect to the latest and most accurate information on state-of-the-art management of cancer pain for patients, caregivers and healthcare professionals.

(Information on the types of Cancer, & the various cancer treatment methods)
Cancer Help UK is the patient information website of Cancer Research UK. We provide a free information service about cancer and cancer care for people with cancer and their families. We believe that information about cancer should be freely available to all and written in a way that people can easily understand.

Comprehensive list of drugs that are used in cancer chemotherapy.

The American Journal of Clinical Oncology.

The Guide to Internet Resources for Cancer family of Web sites established 1996, now with over a thousand pages. It is maintained on a voluntary / not-for-profit basis.

The official journal of the American College of Radiation Oncology, the American Journal of Clinical Oncology is a multidisciplinary journal for cancer surgeons, radiation oncologists, medical oncologists, GYN oncologists, and pediatric oncologists.

World Journal of Surgical Oncology is an Open Access, peer-reviewed, online journal publishing articles related to surgical oncology and its allied subjects such as epidemiology, cancer research, biomarkers, prevention, pathology, radiology, cancer treatment, clinical trials, multimodality treatment and molecular biology. Emphasis is placed on original research articles and clinical case reports. The journal will also provide balanced, extensive and timely review articles on selected topics.

Get the Oncologist approved cancer information from the American Society of Clinical Oncology.

It serves as a source for important and translational clinical studies from around the world.

ASTRO is a medical society for radiation oncologists and other members of the radiation therapy treatment team.

International Seminars in Surgical Oncology is ready to receive manuscripts on all aspects of surgical cancer care.

Head & Neck Oncology encompasses all aspects of clinical practice, basic and translational research on the aetiology, pathophysiology, diagnosis, assessment, management, follow-up and prognosis of patients with head and neck tumours.

It provides a comprehensive list on Cancer information.