The precancer

The precancer disease, pathological conditions and tissue changes prior to cancer; with long-term existence may become cancer. He does not occur at once, immediately, and is only the last link in the long chain of successive changes, due to many internal and external factors. Precancerous changes are often associated with internal biological reasons, such as developmental disabilities, aging of the body and chronic diseases of various organs. On the other hand, the reason they can be various chemical carcinogenic substances, physical agents (UV and radioactive radiation) or their combination.
The fight against precancerous processes necessary for the prevention of cancer; the main form of precancer man firmly established and widely recognized. These include long-existing polyposis of the stomach or bowel, including family, old lingering bronchitis, chronic pneumonia, bronchitis associated with years of Smoking tobacco, old stomach ulcers with sealing edges, old vivorata (ectropion) of the mucous membrane of the uterus on the basis of a deep breaks her neck, growing and orogovevshie white plaques (see Leukoplakia) of the mucous membrane of the mouth, cervix and other resistant skin changes after radiation therapy, scarring of the skin after burns, cutaneous horn, geriatric centers keratinization of the skin, papilloma, scars on the soil erythematosus (TB) skin and so on, to distinguish obligate precancer diseases, sooner or later lead to the development of cancer, for example Bowen disease (see), familial polyposis of the colon, and the optional precancer diseases, leading to cancer, but in a small proportion of cases (for example, bulleznaya stomach ulcer, fibrocystic breast disease).
When deciding about the allocation of a pathological process for precancer and on the degree of proremote transition in cancer should take into account the age of the patient, as well as the possibility of cancer increases with age. Consideration should also be given a chronic course of the process, the persistence of certain symptoms, inefficiency used conservative methods of treatment, relapses after clinical cure. For the treatment of precancerous diseases are successfully applied surgical, radiation and medicinal methods by which can be achieved reliable cure for precancerous lesions. The doctrine of precancer justified itself in practice and formed the basis of widely held prophylactic medical examination of population of the USSR for the detection and timely treatment of precancerous lesions. The nurse should suspicious precancer refer the patient to the doctor for diagnosis and treatment in the future to send it to re-examinations according to doctor's instructions.

The precancer (synonym: precancer, precancers) - a disease pathological condition and tissue changes that naturally precede cancer and the prolonged existence can in large percentage of cases go cancer. In this definition the precancer is characterized with clinical and pathophysiological and biochemical and morphological point of view. From a morphological point of view precancer can be called microscopic, multicentric emerging, often multiple foci noninflammatory atypical growth of immature epithelial (or, for example, fibroblast or osteodes tissue - in the case of pedsakai) with a tendency to infiltrative growth, but even without destroying the fabric.
In Oncology durable reinforced the idea that cancer (see) never comes on suddenly and completely healthy tissues. Developing gradually, he is like a final phase of a long series preceding pathological processes - precancerous lesions.
The term "precancerous" belongs to Dubreuil (W. Dubreuilh), which in 1896 suggested the name "precancerous keratoses" following group of diseases: the senile keratoma, pigmentary xeroderma, ARSENICAL keratosis, skin papillomas among chimney sweeps and working with arsenic, Paget's disease. Following the message of Dubreuil numerous works about precancer long been purely clinical. Morphological, not finding morphological substrate for full features of precancer, this concept has been long recognized. And only with the development of experimental cancer research, they were able to trace in detail the changes that happen to the normal tissue during his transformation into cancer, a number of common patterns of precancer. Experimental Oncology research has invested specific content in the concept of precancer.
To pre-cancerous diseases of the person referred leukoplakia (see) of the mucous membranes of the oral cavity and esophagus (Fig. 1), erythroplasia (see) of the skin, adenomatous polyps in the stomach and large intestine, nutricote and intraductal papillomatosis and adenomatous expansion with fibrocystic mastopathy (Fig.2), HPV bladder (Fig. 3), nonhealing cervical erosion with atypical growths of the epithelium, and the so-called benign tumors that can malignities, for example adenomas buds (Fig. 4).
The ability to get in the experiment and to learn the details of skin cancer, lung, liver, kidney, breast, urinary tract, and so on, and sarcomas of various types and locations, has allowed to establish a number of General regularities of precancer.
In the development of malignant tumors L. M. Chabad distinguishes four stages:
1) uneven diffuse hyperplasia,
2) focal irriterad, 3) relatively benign tumors and 4) a malignant tumor.
For uneven diffuse hyperplasia (first stage) is characterized by a mismatch of morphological structure of the functional value. For example, under the influence of long-term administration of oestrogen hormonal preparations causing in the organism of violation of hormonal mode, in the breast are observed epithelial hyperplasia and galactotes, but without lactation (printing. Fig. 2). In the future against such a diffuse irregular hyperplasia usually multicentric multiple microscopic lesions growth of undifferentiated immature homogeneous cell stage (second) focal growths, or radosnych of proliferation. They can be of different localization and structure depending on the organ or tissue in which they arise (printing. Fig. 1, C and 4). Gradually increasing, radosnie proliferate grow and form separate from the surrounding tissues site that can be called a tumor (printing. Fig. 5 and 6).

the precancer
Fig. 1. Uneven hyperplasia skin cancer, mice exposed to the lubrication of carcinogenic hydrocarbons. Fig. 2. Diffuse irregular hyperplasia of mammary glands in rats due to the introduction of large doses sinestrola. Fig. 3. Focal proliferate and the surface epithelium of the sebaceous glands (1) in the skin of mice that were treated carcinogenic hydrocarbons. Fig. 4. The initial focus of the epithelium of the mammary glands of rats receiving large doses sinestrola. Fig. 5. Small adenoma liver mouse experimentally induced o-aminoazotoluene. Fig. 6. Papillomatosis expansion inside cysts breast cancer in rats caused by sinestrola.

The growth of tumors usually expansive, and therefore it can be called benign (the third stage). In the future, the tumor begins to investirovat and destroy surrounding tissue and goes malignant, i.e. from the third stage to the fourth.
Sometimes focal proliferate acquire the ability to infiltrative and destroyuser growth and directly go into a malignant tumor. In these cases stages conditionally benign tumors is not observed.
Benign tumors may have different potency growth and different fate. In some cases it is slow-growing and relatively little is changing neoplasms, which for many years and even the whole life of a human or animal remains benign. In other cases they represent from the outset only tranzitorno benign tumors and relatively quickly zlokacestvennoe.
Thus, precancerous can be called the changes that can directly jump into cancer (some focal proliferate and the so-called benign tumors). However uneven diffuse hyperplasia can be called not the cancers and precancerous changes, followed likely development of benign tumors. Each cancer has a precancer, but not every precancer turns into cancer.
Along with the General changes, characteristic for all types and locations of precancer, there are features that distinguish each of Peterhof, which allows you to allocate special nosologic unit P., a separate disease.
All kinds of precancerous changes can be divided into two groups: 1) P. arising on the place of initial application of a carcinogenic agent in tissues and organs directly open to the agents of the environment; 2) P. arising away from a place of drawing of primary carcinogenic agent in the so-called closed tissues and organs. The first group includes, for example, pre-cancerous changes of the skin, stomach, lungs. Second - dishormonal precancerous changes, the cancers that occur in the liver, with the experimental carcinogenesis, etc. the Basic difference of these two groups is the presence of the first and the lack of a second of the inflammatory process. The possibility of the absence of inflammation in cancer (see) allows to state that it cannot be seen as a necessary link in the chain of events leading to cancer, so it has no precancerous values.
As shown by numerous experiments, or clinical observation, precancerous and precancerous changes on the famous stage can stay in the further development and even be subject to involution. This applies, for example, to the dishormonal hyperplasia and proliferation mammary and prostate glands, the skin papillomas and so on Reversibility of precancerous changes is the main difference of precancer from cancer. Regression of pre-cancerous lesions is usually observed under the influence of weak carcinogenic agents at a lower dosage or upon termination of a carcinogenic effect. The possibility of regression precancerous changes shows that the cure them real.
Along with morphological was identified and a number of operational changes that precede the advent of the cancer, and not only in the place of its occurrence, but in the distant tissues and organs. The last concern violations of hormonal balance, metabolism, protein and is closely associated with the exchange of nucleic acids and carbohydrate metabolism (R. E. Kavetsky, I. M. Neumann). The described changes of different departments of the Central nervous system and the higher nervous activity. It is believed that in pre-cancerous period, as at the early stage of cancer, dominated by the processes of excitation and subsequent inhibition processes. In light of these new data, the concept of precancer acquired specific content, although it is not yet fully disclosed neither clinical nor from a morphological point of view. Many morphological still continue to argue that because even for a fully developed cancer cell there is no absolutely reliable criteria of malignancy, it can hardly be morphologically detectable changes in cells and tissues, which could be considered reliable predecessors cancer [Bungler (W. Biingeler)].
According to the decision of II all-Union cancer conference (1958) proposed a wide clinical concept of precancer to distinguish between two phases - "background process" as the early phase and actually precancer. The early phase should include the whole group of precancerous diseases. Strictly speaking, P. - only identified on the background of each of these focal diseases, often multiple proliferate as papillary, adenomatous or solid growths.
Depending on the frequency with which motivated or other precancerous disease or condition occurs cancer, there are obligate precancer, each case is naturally turns into cancer, if not we will take appropriate treatment and preventive measures, and the optional P., which is relatively often, but not necessarily goes into cancer. To obligate predracun include: pigmentary xeroderma, cutaneous horn, familial polyposis of the colon, Bowen's disease (Fig. 5) and Paget's disease. However, the latter two forms most authors refers not to Petrograd, and to vnutriepetelialnaya cancer.
As precancer is not stable pathological form, and the process in a dynamic of its development, it has no special clinical picture. Symptoms it mainly reflects the clinic relevant background process. And only the duration of the disease and its progression, the insufficient effectiveness of remedial measures, recurrence after achieving clinical cure allow us to speak with each case of P. in the narrow sense the words. On the same grounds and the time of precancer in cancer does not give an accurate account. But based on the experience we can assume that at surface forms P , available to the inspection and palpation, all kinds of new, unreasonable changes in the condition of P. (marked increase daily education, increase its size as on the surface and in depth, seal and especially the appearance on the surface piercing erosions, ulcers or warty growths), should be considered suspicious of transition in cancer. And the more persistent and progressive these changes, the more reasonable become suspicious.
Similarly, when precancerous diseases of internal organs suspicious outbreak of malignancy should be considered as the appearance in routine clinical picture of a disease new functional disorders: unmotivated General weakness, fatigue, declining capacity to work and when precancerous conditions of the gastrointestinal tract, moreover, the emergence of unmotivated persistent reduction of appetite, stomach discomfort, unreasonable progressive weight loss, the phenomena of mental depression.
The vagueness and some ambiguity in these clinical signs of malignization precancerous processes emphasize the imperfection of our knowledge about the true nature P.
The study of cancers in experimental-morphological aspect contributes to the disclosure of the pathogenesis of cancer. In particular, it shows a gradual development, which is fully in view of the progression of tumors.
However, a comprehensive study of precancerous conditions and changes promotes correct diagnosis and early detection and effective treatment of these diseases, and hence the prevention of cancer. It is widely held in our country mass preventive examinations of the population have already produced significant results in reducing morbidity and mortality from cancer (see Tumors).

Fig. 1. Leukoplakia of the esophagus; uneven hyperplasia of epithelial mucous membranes.
Fig. 2. Motricity papilloma with fibrocystic mastopathy.
Fig. 3. Papilloma bladder.
Fig. 4. Multiple adenomas kidneys.
Fig. 5. Bowen's disease; uneven hyperplasia of the epithelium of the skin.