A tumor ( plural tumors , colloquially also tumors ; from the Latin tumor , -oris , m. 'Growth', 'tumor', 'swelling'; cf. Latin tumescere "swell") or a swelling in the broader sense is any increase ( swelling ) the volume of a circumscribed tissue of higher living beings regardless of the cause (in particular inflammation, edema and cancerous tumors). Synonyms in a second, narrower meaning are the terms neoplasia (“new formation”) and “growth” and primarily denote uncontrolled growth of cells. Tumors occur in all higher living beings ( including plants ). However, this article only deals with tumors in humans, i.e. their medical significance.
Accordingly, there are two definitions of the term tumor in medicine :
- in the broader sense, any increased space requirement (space occupation) of a tissue ( intumescence ) or a palpable hardening, e.g. B. swelling in the case of an inflammation ( edema , phlegmon , abscess ) or cyst (see also pseudotumor ), or an accumulation of stool in the intestine, which can often be felt in the left lower abdomen before a bowel movement. So it's a rather vague term.
- In the narrower sense, new formations of body tissues (neoplasias), which arise from dysregulation during cell proliferation - whereby nothing is said about the benign or malignant nature ( dignity ) of the new formation.
Neoplasms can affect any type of tissue, they can be benign ( benign ) or malignant ( malignant ). The malignant variant is also known colloquially as cancer . Neoplasms can appear alone ("solitary") or several times in different places in the organism ("multicentric" or "multifocal"). Typically, tumors are referred to as multicentric if the distance between the individual lesions is more than five centimeters and multifocal if the distance is five centimeters or less, but there is no exact radiological definition for these terms. Depending on the location (localization) of the tumor and the function of the tissue damaged by it, they can lead to the destruction of organs with impairments to the entire organism and even death.
Tumors are tissue changes that are also hereditary, but are generally not contagious in humans. They are classified according to their biological growth behavior and the tissue of origin of the neoplasm.
Depending on the dignity of the tumor, i.e. its ability to develop metastases , a distinction is made between benign (benign) , malignant (malignant) and semimalignant tumors. The malignant tumors are further subdivided into low-malignant and high-malignant tumors.
- As a result of their growth, benign (benign) tumors displace surrounding tissue, but do not grow through ( infiltrate ) it and do not form colonies .
- Malignant tumors are malignant tumors. These tumors are often referred to as cancer . They are invasive , which means that they grow into surrounding tissue and destroy it. In addition, they spread daughter tumors in the blood ( hematogenous ), via the lymph ( lymphogenous ) or by draining, for example in the abdominal cavity . Typical malignant tumors are colon cancer and lung cancer .
- Semimalignant tumors generally do not create daughter tumors , but destroy the surrounding tissue and grow into it ( destruction and infiltration ).
|growth||slowly , suppressing||fast , invasive|
|Differentiation from healthy tissue||easy to define (e.g. capsule, pseudocapsule)||difficult to define|
|differentiation||well differentiated , homogeneous tissue||immature , heterogeneous tissue|
|Cell changes||no or few cell changes
low mitotic activity
|High mutation rate, many atypical changes (atypia), high rate of cell division|
|course||long lasting , few symptoms, no metastases , rarely relapses||short, often fatal, metastases , often relapses|
Benign tumors and semi-malignant tumors are further differentiated according to their origin. The name is given by the suffix "-om" attached to the Latin name of the original fabric.
Malignant tumors are also named after this original tissue - provided the original tissue is still recognizable and the tumor is not completely dedifferentiated. However, this nomenclature is not followed consistently, so that other terms are also used for it (e.g. signet ring cell carcinoma according to the appearance of the tumor cells). Malignant tumors are called cancer in German (even if cancer is the translation of the Greek word 'Καρκινος', and thus only one - albeit the most common - group of malignant tumors is referred to).
Malignant tumors can develop from not yet malignant preliminary stages, so-called precanceroses . These are divided into facultative and obligatory precancerous diseases.
The malignant tumors are subdivided as follows:
- Carcinomas are malignant tumors that are derived from the epithelium . They make up a large part of cancer.
- Sarcomas (Greek σάρξ, sarx , meat), which are derived from the connective and supporting tissue, for example
- neuroendocrine tumors derived from the neuroectoderm , for example
- Haemato-oncological malignancies derived from blood or blood stem cells
- Dysontogenetic tumors
- Embryonic tissue teratomas (all three cotyledons)
- Embryonic tumors (arise during organ development due to incorrect differentiation of tissue)
- Mixed tumors made up of epithelial and mesenchymal components
The further classification of malignant tumors is based on the TNM classification of the UICC . It is a clinical-empirical classification, which determines the further diagnosis, therapy and prognosis of malignant tumors.
Classification according to ICD-10
Classification according to WHO
T classification (size of the tumor):
- T 1–3: tumor is restricted to the original organ
- T 4: tumor infiltrates other organs
N classification (lymph nodes):
- Absence or presence of regional lymph node metastases
M classification (metastases):
- Presence or absence of distant metastases 0–1
R classification (resection):
- Microscopic resection = 0 (no residual tumor)
- Microscopic resection = 1 (residual tumor present)
- Resection with macroscopically remaining residual tumor = 2
G classification (grading):
- G1 to G4 good differentiation (similar to the original tissue) to extremely malignant
The location of the tumors is the essential basis of the classification of the neoplasms in the International Statistical Classification of Diseases and Related Health Problems (ICD-10) published by the WHO .
Tumors arise through degeneration, more precisely through an accumulation of mutations in certain genes ( multiple hit model ). These particular genes are typically proto-oncogenes or tumor suppressor genes . Alternatively, degeneration by oncoviruses and oncogenic bacteria can occur, in which continuous stimulation with cytokines occurs through the immune reaction and with growth factors to replace the destroyed cells, e.g. B. in the hepatitis B virus . Frequent cell division promotes mutations when the genome is copied . In the case of some persistent viruses (the genomic-integrating viruses ), an insertion mutation also takes place by inserting the viral genome into the host's genome , which usually takes place in areas of the DNA that are unfolded and active in transcription , e.g. B. in retroviruses . In rare cases, a tumor can also be transmitted, e.g. B. through an organ transplant and the accompanying immunosuppression or - in dogs, devils and hamsters - through infectious tumors .
Effects of tumors on the body
Benign tumors usually grow slowly and do not affect the body. However, some benign tumors can mutate into malignant tumors . Colon polyps (colon adenomas ), which very often degenerate into adenocarcinomas (so-called adenoma-carcinoma sequence ), should be mentioned here. However, hormone-producing adenomas can lead to serious illnesses due to their hormonal effects.
Complications of benign and malignant tumors are:
- Pressure atrophy due to growth (e.g. leads to hormone deficiency in tumors in endocrine glands).
- Minor obstruction of lumina = obstruction of hollow organs with cyst formation.
- Ectopic hormone production e.g. B. ACTH , parathyroid hormone or insulin .
Complications of malignant tumors are:
- Severe obstruction of hollow organs, e.g. B .:
- Tumor cachexia : atrophy of muscle and adipose tissue, anorexia , anemia , weakness. The energy requirements of tumor cells are often met by lactic acid fermentation , which leads to hypoglycemia and acidosis , which in turn triggers the release of adrenaline , glucocorticoids and glucagon . This promotes lipolysis as well as proteolysis , which leads to the above-mentioned atrophy and ultimately emaciation. Presumably caused by TNF-α and other cytokines .
- Tissue destruction, often with bleeding. Adenocarcinomas tend to form ulcers by destroying the surface epithelium.
- Edema from occlusion of veins and lymph vessels .
- Paraneoplastic syndromes : These are symptoms that cannot be explained directly from the localization or the type of tumor, diseases of the nerves and muscles ( myasthenia ), hypertrophic osteoarthropathy ( drumstick fingers , watch glass nails ), thrombophlebitis , etc. In the case of inexplicable occurrence of paraneoplasia, a tumor search is essential .
Tumor therapy takes place through surgical removal of the tumor ( resection , also awake craniotomy for certain brain tumors), irradiation with ionizing radiation and / or (poly) chemotherapy . Affected people can visit a tumor counseling service .
For some specific malignant tumors, there are additional, special treatment options. Cancer immunotherapies are in the developmental stage against malignant melanoma , the so-called black skin cancer , in which the body is vaccinated with special surface antigens, i.e. cell characteristics of malignant melanoma. A similar concept is being pursued for some tumors, for example gastrointestinal stromal tumors, with treatment using immunomodulators, in which the body's immune system is stimulated to target tumor cells.
Other tumors are additionally treated with local heat, by sticking blood-supplying vessels or with locally administered poisons. However, these therapy options are all reserved for certain malignant tumors and only make up a small part of the therapy performed. It is known that tumor vaccination against melanomas in dogs has at least the same therapeutic success as chemotherapy, but with far fewer or no side effects (I. Kurzman, University of Wisconsin, Madison). In horses there are already numerous positive experiences with malignant tumors and sarcoids with a vaccine with dendritic cells. In addition, there are forms of treatment in the field of complementary medicine , which, however, cannot replace the aforementioned, but are only to be understood as supplementary measures.
Benign tumors are very common. Most people have multiple benign tumors, mostly on the skin. Some primarily benign tumors can degenerate into malignant tumors and must be removed. This is especially the case with polyps in the lining of the colon . People often find benign tumors of the skin to be cosmetically annoying. B. are irritated in body folds, so that a removal also makes sense here.
- HJ Peters u. a .: Tumor vaccination: Dendritic cells as activators of the specific immune reaction in research and clinic. In: Deutsche Zeitschrift für Onkologie 2004 (39), pp. 57–64.
- H. Löwen: Tumors. In: Alfred Czarnetzki (Hrsg.): Mute witnesses of their suffering. Illness and Treatment Before the Medical Revolution. Attempto, Tübingen 1996, ISBN 3-89308-258-1 , pp. 133-157.