Diagnosis

Most cancers are initially recognized either because signs or symptoms appear or through screening. Neither of these lead to a definitive diagnosis, which usually requires the opinion of a pathologist.

Investigation

People with suspected cancer are investigated with medical tests. These commonly include blood tests, X-rays, CT scans and endoscopy.
Biopsy

A cancer may be suspected for a variety of reasons, but the definitive diagnosis of most malignancies must be confirmed by histological examination of the cancerous cells by a pathologist. Tissue can be obtained from a biopsy or surgery. Many biopsies (such as those of the skin, breast or liver) can be done in a doctor's office. Biopsies of other organs are performed under anesthesia and require surgery in an operating room.


The tissue diagnosis indicates the type of cell that is proliferating, its histological grade and other features of the tumor. Together, this information is useful to evaluate the prognosis of this patient and choose the best treatment. Cytogenetics and immunohistochemistry may provide information about future behavior of the cancer (prognosis) and best treatment.

Behavioral health

Behavioral health

Behavioral health was first used in the 1980's to name the combination of the fields mental health and substance abuse. As an example, an organization serving both mental health and substance abuse clients might refer to its practice as behavioral health or behavioral health care. The term is often simply abbreviated BH and is quite commonly used. A large national association of treatment providers, the National Council for Community Behavioral Healthcare (NCCBH), is one highly visible example. The term is somewhat controversial, however, since the word behavioral suggests a psychological cause and treatment for substance abuse (or substance dependence), rather than a medical or disease-model cause and treatment as some experts assert.

Cancer

diseases in which cells are aggressive (grow and divide without respect to normal limits), invasive (invade and destroy adjacent tissues), and sometimes metastatic (spread to other locations in the body). These three malignant properties of cancers differentiate them from benign tumors, which are self-limited in their growth and don't invade or metastasize (although some benign tumor types are capable of becoming malignant). Cancer may affect people at all ages, even fetuses, but risk for the more common varieties tends to increase 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. Apart from humans, forms of cancer may affect other animals and plants.

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. Complex interactions between carcinogens and the host genome may explain why only some develop cancer after exposure to a known carcinogen. New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are increasingly being recognized as important.

Genetic abnormalities found in cancer typically affect two general classes of genes. Cancer-promoting oncogenes are often 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 often 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.

Cancer is usually classified according to the tissue from which the cancerous cells originate, as well as the normal cell type they most resemble. These are location and histology, respectively. A definitive 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.

Preventive medicine

Preventive medicine

Generally speaking, preventive medicine is the part of medicine engaged with preventing disease rather than curing it. It can be contrasted not only with curative medicine, but also with public health methods (which work at the level of population health rather than individual health).

Professionals involved in the public health aspect of this practice may be involved in entomology, pest control, and public health inspections. Public health inspections can include recreational waters, pools, beaches, food preparation and serving, and industrial hygiene inspections and surveys.

As a medical specialty

In the United States, preventive medicine is a medical specialty, one of the 24 recognized by the American Board of Medical Specialties (ABMS). It encompasses three areas of specialization:

* General preventive medicine and public health
* Aerospace medicine
* Occupational medicine

In order to become board-certified in one of the preventive medicine areas of specialization, a licensed U.S. physician (M.D. or D.O.) must successfully complete a preventive medicine medical residency program following a one year internship. Following that, the physician must complete a year of practice in that special area and pass the preventive medicine board examination. The residency program is at least two years in length, and includes completion of a post-graduate masters degree in public health (MPH) or equivalent. The board exam takes an entire day: The morning session concentrates on general preventive medicine questions. The afternoon session concentrates on the one of the three areas of specialization that the applicant has studied.

In addition, there are two subspecialty areas of certification:

* Medical toxicology (MT)
* Undersea and hyperbaric medicine (UHB), formerly "undersea medicine"

These certifications require sitting for an examination following successful completion of an MT or UHB fellowship and prior board certification in one of the 24 ABMS-recognized specialties.

Research funding

Research funding in many countries comes from research bodies which distribute cash for equipment and salaries. In the UK, funding bodies such as the Medical Research Council and the Wellcome Trust derive their assets from UK tax payers, and distribute this to institutions in a competitive manner.

In the United States, the most recent data from 2003 suggest that about 94 billion dollars were provided for biomedical research in the United States. The National Institutes of Health and pharmaceutical companies collectively contribute 26.4 billion dollars and 27.0 billion dollars, respectively, which constitute 28% and 29% of the total, respectively. Other significant contributors include biotechnology companies (17.9 billion dollars, 19% of total), medical device companies (9.2 billion dollars, 10% of total), other federal sources, and state and local governments. Foundations and charities, led by the Bill and Melinda Gates Foundation, contributed about 3% of the funding.

Preclinical research

Preclinical research is research in basic science, which precedes the clinical trials, and is almost purely based on theory and animal experiments.

New treatments come about as a result of other, earlier discoveries — often unconnected to each other, and in various fields. Sometimes the research is done for non-medical purposes, and only by accident contributes to the field of medicine (for example, the discovery of penicillin). Clinicians use these discoveries to create a treatment regimen, which is then tested in clinical trials.

Clinical trials

A clinical trial is a comparison test of a medication or other medical treatment, versus a placebo, other medications and devices, or the standard medical treatment for a patient's condition. Clinical trials vary greatly in size: from a single researcher in one hospital or clinic to an international multicenter trial with several hundred participating researchers on several continents. The number of patients tested can range from as few as 30 to several thousands.

Biomedical research

Biomedical research (or experimental medicine), in general simply known as medical research, is the basic research or applied research conducted to aid the body of knowledge in the field of medicine. Medical research can be divided into two general categories: the evaluation of new treatments for both safety and efficacy in what are termed clinical trials, and all other research that contributes to the development of new treatments. The latter is termed preclinical research if its goal is specifically to elaborate knowledge for the development of new therapeutic strategies.

The increased longevity of humans over the past century can be significantly attributed to advances resulting from medical research. Among the major benefits have been vaccines for measles and polio, insulin treatment for diabetes, classes of antibiotics for treating a host of maladies, medication for high blood pressure, improved treaments for AIDS, statins and other treatments for atherosclerosis, new surgical techniques such as microsurgery, and increasingly successful treatments for cancer. New, beneficial tests and treatments are expected as a result of the human genome project. Many challenges remain, however, including the appearance of antibiotic resistance and the obesity epidemic.

Most of the research in the field is pursued by biomedical scientists in cooperation with molecular biologists.

Post-graduate education

Following completion of entry-level training, newly graduated doctors are often required to undertake a period of supervised practice before full registration is granted; this is most often of one year duration and may be referred to as "internship" or "provisional registration" or "residency".

Further training in a particular field of medicine may be undertaken. In some jurisdictions this is commenced immediately following completion of entry-level training, whilst other jurisdictions require junior doctors to undertake generalist (unstreamed) training for a number of years before commencing specialisation.

Entry-level education

Entry-level medical education programs are tertiary-level courses undertaken at a medical school. Depending on jurisdiction and university, these may be either undergraduate-entry (most of Europe, India, China), or graduate-entry programs (mainly Australia and Canada), or Second entry degrees (United States).

Generally, initial training is taken at medical school. Traditionally initial medical education is divided between preclinical and clinical studies. The former consists of the basic sciences such as anatomy, physiology, biochemistry, pharmacology, pathology. The latter consists of teaching in the various areas of clinical medicine such as internal medicine, pediatrics, obstetrics and gynecology, psychiatry, and surgery. Increasingly, however, medical programs are using systems-based curricula in which learning is integrated, and several institutions do this.

There has been a proliferation of programmes that combine medical training with research (MD PhD) or management programmes (MD MBA), although this has been criticised.

Medical education

Medical education is education connected to the practice of being a medical practitioner, either the initial training to become a physician or further training thereafter.

Medical education and training varies considerably across the world, however typically involves entry level education at a university medical school, followed by a period of supervised practice (Internship and/or Residency) and possibly postgraduate vocational training. Continuing medical education is a requirement of many regulatory authorities.

Various teaching methodologies have been utilised in medical education, which is an active area of educational research.

Presently, in England, a typical medicine course at university is 5 years (4 if the student already holds a degree). Amongst some institutions and for some students, it may be 6 years (including the selection of an intercalated BSc - taking one year - at some point after the pre-clinical studies). This is followed by 2 Foundation years afterwards, namely F1 and F2. Students register with the UK General Medical Council at the end of F1. At the end of F2, they may pursue further years of study.

In the US and Canada, a potential medical student must first complete an undergraduate degree in any subject before applying to a graduate medical school to pursue an (M.D.) program. Some students opt for the research-focused MD/PhD dual degree, which is usually completed in 7-8 years.

In Australia, there are two pathways to a medical degree. Students can choose to take a five or six year undergraduate medical degree Bachelor of Medicine/Bachelor of Surgery (MBBS or BMed) straight from high school, or complete a bachelors degree (generally three years, usually in the medical sciences) and then apply for a four year graduate entry Bachelor of Medicine/Bachelor of Surgery (MBBS) program.

Medicine

Medicine is the science and "art" of maintaining and/or restoring human health through the study, diagnosis, and treatment of patients. The term is derived from the Latin ars medicina meaning the art of healing.

The modern practice of medicine occurs at the many interfaces between the art of healing and various sciences. Medicine is  directly connected to the health sciences and biomedicine.

Broadly speaking, the term 'Medicine' today refers to the fields of clinical medicine, medical research and surgery, thereby covering the challenges of disease and injury.