PRETUMOR DISEASES (synonym: pretumor states, precancer) — diseases and pathological processes against the background of which development of malignant tumors is possible.
Idea of P. z. it developed on the basis it is long collecting a wedge. observations and pilot studies. The term «precancer» began to be applied after in 1896 on the International congress of dermatologists in London W. Dubreuilh in the report on keratoza called them predecessors of cancer. Further the concept «precancer» was extended to the corresponding processes in other bodies and fabrics. However and before
C. I. Kostarev, M. M. Rudnev, P. Pott, L. Rehn stated the idea about developing of cancer against the background of various is long the proceeding diseases of not tumoral character.
Unanimity of views on the importance previous patol, processes in development of cancer and other malignant tumors does not exist.
In this regard wedge. the concept «pretumor diseases» quite often insufficiently reasonably extends before idea of obligation of pretumor diseases for each form of a malignant tumor though at the same time it is emphasized that not each P. z. surely passes into a malignant tumor.
Insufficiently accurately certain notions of P. z. and in morfol. aspect. At different stages of formation of this concept it is possible to note as extremely reserved attitude towards him based on absence enough accurate morfol, criteria and insufficiently justified expansion of this concept. Thus, problem P. z. completely it is not solved neither with clinical, nor from morphological positions.
On the basis of studying arising at experimental cancer, morfol. changes at the stages preceding development of cancer natural changes of a superficial and ferruterous epithelium are revealed. It allowed L. M. Shabadu to formulate the concept «precancer» in morfol. aspect as «multitsentrichno the arising centers of growth of an atipichesky unripe epithelium of the noninflammatory nature with bent to infiltrative growth, but without destruction of fabric».
The changes previous according to biopsy and section material, to development of cancer in the person, allow to note considerable similarity of the sequence of development of experimentally induced cancer to what is observed at the person. However by consideration of pretumor changes the person in kliniko-morphological aspect has certain difficulties, e.g. concerning assessment of a diffusion hyperplasia (tumoral process or dystrophic changes of an inflammatory origin at various patol. states). Equally it belongs also to regenerative growths which interpretation as predo pukholevy changes can meet insuperable difficulties. By consideration of phase precancerous changes with the help morfol. a method it is not always possible to reveal development of cancer in a nodose proliferat or in a benign tumor, and the center of malignant growth (e.g., cancer thyroid or a prostate) is defined in these cases in probably not changed part of body.
Treatment and objective assessment of P. z. are very difficult. It is almost important to allocate background processes, under to-rymi it is accepted to understand everything patol, the changes preceding development of a malignant tumor. Can be carried to them hron. nonspecific and specific inflammatory diseases, e.g. hron. bronchitis (see), recurrent pneumonia (see), it is long not healing ulcers and fistulas, skin hems, a dishormonal hyperplasia of mammary glands knotty (fibroadenomas) or diffusion (adenoses) of type, hron. atrophic gastritis (see) and peptic ulcer (see) stomach. Development of cancer from background processes is observed rather seldom.
It is necessary to refer to actually precancer generally only proliferative changes of focal character which arose against the background of the specified processes. So, from dishormonal giperplaziya of mammary glands only those can be carried to actually precancer at which resistant focal proliferata of an epithelium in channels, segments or cystous cavities morphologically come to light. Among numerous forms of gastritis only atrophic gastritis with the expressed degree of an atrophy and deep restructuring of a mucous membrane of a stomach can be carried to a precancer. Frequency of development zlokachest at the same time is higher than a wine tumor, than at other forms of gastritis.
P.'s variety z., various frequency of development of cancer at different diseases led to obligate and optional P.' allocation z. In obligate P.' concept z. include genetically predetermined processes at which development of a malignant tumor is most often observed. Carry a pigmental xeroderma to them (see. Xeroderma pigmental ), Bowen's disease (see. Bowen disease ), Keyr's disease (see. Keyra eritroplaziya ), Dyubrey's melanosis (see. Melanosis ), inborn multiple polyposes of a large intestine. At a pigmental xeroderma surely over time there is a development of a malignant tumor — usually planocellular cancer (see), is more rare — bazalioma (see), is even more rare — melanomas (see) or sarcomas (see). Bowen's disease (skin, are more rare than a mucous membrane of a mouth) is carried to intraepithelial cancer, but on a wedge. to a current it can be considered as an obligate precancer since existence of single, is more rare multiple, plaques can be long-term, with very slow progression. However over time the low-differentiated planocellular cancer naturally develops, at Krom metastasises quickly appear. The same obligate form, it is obligatory for the leader to development of planocellular cancer with bystry innidiation in regional (inguinal) limf. nodes, Keyr's disease is, to-ruyu also carry to intraepithelial cancer. At it process is most often localized on a balanus, is much more rare — on external genitals at women and is even more rare — on a mucous membrane of a mouth.
Development of a melanoma against the background of a limited melanosis of Dyubrey is also observed almost in all cases. At inborn diffusion to a polypose of the large intestine which is the most threatened concerning development of cancer the adenopapillomatozny form is. At it, according to D. K. Kamayeva (1980), in 80% of observations development of cancer is noted.
Optional P. z. are usually deprived of inborn and hereditary properties, they make more extensive group, are observed more often and not necessarily pass into cancer or sarcoma. On a red border of an under lip (see. Lips ) optional P. z. the keratoacanthoma, different types diffusion and focal (productive and destructive) dyskeratoses are. Development of cancer on this background is observed in 5 — 10% of cases, and at a keratoacanthoma certain researchers point to more high frequency voznikno veniye of cancer (20%). On a mucous membrane of a mouth (language, a mouth floor, a cheek) optional P. z. are leukoplakia (see) or towering over a surface white rough (single or multiple) educations — the leukokeratosis, is more rare — single or multiple papillomatous growths, and also superficial not healing ulcers (is more often as a result of a constant injury carious teeth or dentures). In this group also damages of a mucous membrane at red flat herpes can be referred (see. Deprive red flat ). Rather accurately and with high degree of statistical probability the frequency of development of cancer against the background of these states is not determined. By data A. L. Mashkilleysona, cancer of a mucous membrane of a mouth develops in 19,5% of cases against the background of a leukoplakia, in 5% — against the background of a trophic ulcer, in 11,5% — against the background of papillomatous growths, in 7,3% of cases — against the background of hron. inflammatory processes.
Optional P. z. cavities nose (see) and nasopharynxes are papillomas and adenomatous polyps (see. Polyp , polyposes). Also benign tumors of small sialadens which are usually mixed can be a source of development of cancer tumors (see).
To optional P. z. throats carry a leukoplakia, pachydermia (see), fibroma on the wide basis (see. Throat ). According to M. I. Svetlanov, V. S. Pogosov, I. A. Triantafilidi, I. L. Kurilin and V. I. Gorbachevsky, development of cancer on their background is observed in 3 — 18% of cases.
P. z are indistinctly allocated. thyroid gland. In an experiment L. M. Shabad and R. I. Akimova showed that development of cancer thyroid gland (see) passes quite often through phases of diffusion and focal proliferation. Development of cancer of thyroid gland, according to a number of researchers, is observed against the background of knotty forms of a craw or adenoma that allows to carry them to optional P. z.
Optional P. z. mammary gland (see) proliferative forms are mastopathies (see) or a fibrosing adenosis, and also intra pro-current papillomas or papillomatous growths in large cysts at a mastopathy. Development of cancer against the background of a fibrosing adenosis is observed in 15 — 20% of cases. More seldom (in 1 — 1,5% of cases) cancer develops from fibroadenomas (see), to-ruyu also carry to optional P. z.
Accurate allocation of P. z. there are no lungs. Apparently, optional P. z. there can be adenoma of a bronchial tube since in it quite often (according to S. D. Pletnev, in 6 of 45 remote adenomas) signs of a malignancy are found.
To optional P. z. gullet (see) can be carried a leukoplakia, hron. esophagitis (see), ulcers, hems after burns, polyps. To determine the frequency of development of cancer against the background of these P. z. difficult, but on the frequency of identification of initial intraepithelial and invasive forms of cancer it is indirectly possible to assume that the frequency of development of cancer against the background of these diseases makes 3 — 5%.
Optional P. z. stomach (see) are hron. gastritis (atrophic, diffusion and focal), peptic ulcer, polyps and polyposes. A. I. Savitsky, A. V. Melnikov, A. I. Rakov consider that it develops in 25 — 75% of all cases of a carcinoma of the stomach against the background of atrophic gastritis. Yu. M. Lazovsky, V. I. Ryatsep do not give so big role in development of cancer to atrophic gastritis, specifying that only at the expressed reorganization of a mucous membrane this disease can be estimated as pretumor. According to A.S. Fedoreev, based on gistol, studying of the resected stomachs, development of cancer at a peptic ulcer is observed in 10 — 15% of cases. Data on the frequency of development of a carcinoma of the stomach from polyps are contradictory. At the increase in the sizes of big polyps revealed by dynamic observation more high frequency of development of cancer is obvious. At gistol, a research of the material received after operational treatment of polyps of a stomach in them signs of tumoral growth seldom are found. Morfol. researches of material biopsies (see), executed at a fibroskopiya (see. Endoscopy ) give the chance more reasonably to judge character of a polyp, its precancerous state.
To optional P. z. a large intestine carry nonspecific ulcer colitis (see. Ulcer nonspecific colitis ) and single adenomatous polyps. Development of cancer against the background of hron, ulcer colitis is observed in 2 — 17% of cases. Frequency of development of cancer on average makes 10% in this connection the method of the choice should be considered their operational removal of single adenomatous polyps of a large intestine.
Optional P. z. external genitals are a leukoplakia and krauroz vulvas (see).
Optional P. z are quite numerous. necks of uterus. Carry a leukoplakia to them, especially with sites of warty growths, cracks, ulcerations, eritroplakiya (see), follicular and papillary erosion (see. Erosion of a neck of uterus ), polyps of the channel of a neck of a uterus less often than a vulval part of a neck uterus (see). Increase of extent of proliferation of an epithelium, its multiple layers and immersion in depth of fabric increases the frequency of development of cancer.
Pretumor optional diseases are also a hyperplasia, polyposes and adenomatosis of an endometria.
For a number of bodies of P. z. are not defined. It, as well as the ambiguities stated above in definition a wedge, and morfol. P.'s characteristics z., creates difficulties in their prevention and treatment. And between that real direction of prevention of malignant tumors P.'s treatment z is. As P.'s development z. it is usually connected with influence of the factors having the leading value in development of malignant tumors, elimination or reduction of their action can be a basis of prevention of P. z., at the same time and tumors.
See also Tumours .
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G. V. Falileev.