Potentials of NLS method in diagnosing gastric and calonic cancers

 The nonlinear diagnostics method (NLS) used in the Oberon device has been actively practiced lately at many medical institutions. The most tangible results were achieved by using the NLS method as a means of dispensary observation. In the course of its development and advancement the method has become a foremost tool of diagnostics and observation with respect to a number of widespread digestive organs diseases; it allows to promptly collect detailed information about a lesion and its pattern and assess the treatment efficiency. That kind of diseases include gastrodoudenal ulcer, chronic gastri tis, and also benign and malignant gastric and colonic tumors. The specific character and working conditions of the therapeutic and clinical institutions in Russia allow to extensively employ the NLS method not only for diagnos ing diseases with some symptoms present but also for dispensary observation, and what is more, practically all the patients in need of examination can be placed under observation. So the physicians can now cover patients with the changes that are latent and can only be verified by means of NLS. Specifically, such patients include those having precancerous diseases or a mucous distur bance in the upper and/or lower sections of the digestive tract and patients who developed a tumor, which still remains latent in a certain phase.

 According to the data acquired by some medical specialists, using the device for NLSdiagnostics, and based on annual research in thousands of cases, the frequency of detecting focal or diffuse changes, typical for chronic atrophic gastritis in patients over 50 years old, is within 3040%. The analy sis of the spectral examinations of patterndifferent sections of focal changes in stomach mucosa shows that different symptoms of diseases including intestinal metaplasia and epithelial dysplasia can be detected in them just as often. During NLS analysis symptoms of gastric ulcer were recorded in about 5% of cases, polyps in stomach in 7% and polyps in colon in 45% of cases. Thus, even the NLS analysis results alone, without other risk factors taken into account, indicate that most of the patients in the respective age group appear to be among those who need dynamic observation because of poten tial gastric cancer (GC) or colonic cancer (CC).

According to the cancer register for 19992000, the values of gastric and colonic cancer cases were 80.9 and 53.1 respectively per 100000 patients, and the death rate according to the mortality statistics was 47.35 and 19.5%. According to the conclusions of therapydiagnosis unit, with around 70% of patients under active dispensary observation, the pathologies of that kind are likely to be detect ed as often as in 0.40.8 % of cases. Therefore, the NLS screening would allow to detect GC or CC in about every 150th200th examinee.

Considering that the emergence of clinical signs is one of the incentives for a patient to take medical advice and a reason for hardwarebased exami nation, some clinical implications and their pattern were evaluated in the cases of the above mentioned diseases. As followed from the results, in 720 patients affected by GC or CC the condition appeared to be symptomfree in 42% and 32% of cases respectively or there were some signs characteristic of previous chronic digestive tract diseases. That was the case in 77% and 92% for the 1st phase, 56% and 68% for the 2nd phase, 23% and 32% for the 3rd phase, and 8% for the 4th phase of the disease. The clinical implications at a gastric cancer were of a paindyspepsia syndrome nature typical for the lesion in the upper section of the digestive tract. At a colonic cancer subgroups were segregated with dominating signs of intestinal hemorrhage, disturbed evacu ation or abdominal pain. A certain interrelationship was proven between the pattern of the clinical implications and the process localization. In more than 50% of cases the clinical implications lasted less than 3 months and in 26% of patients the CC developed acutely within a few days. It should be noted that the socalled "minor sign syndrome" corresponded to some later phases of the disease. The same was true for lab examination data where the change became evident during phases III and IV (2).

The results of NLSdiagnostics for the initial phases of gastric cancer in a series of 104 examinations showed that in 72% of cases the physician on the assumption of a spectral similarity to the reference standard, regarded the lesion as benign and indicative of focal mucosa hyperplasia, polyp, an area of local inflammation, wall deformation or a small ulcer. The probability for detecting signs of malignant change found out in the elimination mode was under 1%. Of 134 cases of colonic cancer in phase 1 malignant adenomas were detected in 58% of patients. The rest of the patients were found to have the cocalled "minor" forms of cancer, like polyps, atrophic gastritis or atrophichyper plastic gastritis. The endoscopic verification of GC and CC with reference to the diacrisis of phases II, III and IV of the diseases com pletely confirmed the results of the NLSinvestigation.

 172 patients were found to have GC or CC discovered by NLSexamina tion conducted within a less than a year interval. Among them 62% of patients had an initial phase of gastric cancer and 38% of the patients during previous observation were found to have some or other signs of chronic gastritis in the form of focal mucosa hyperplasia, local inflammation or wall deformation. According to morphological investigation, the said sections were of a benign nature and cancer developed therein over the last year only. In the rest of the patients the macroscopic changes corresponding to malignant affection (spec tral similarity to "gastric carcinoma" reference standard D<0.425) occurred in the span between the last two examinations. The preceding endoscopy detect ed atrophic gastritis free of focal changes in the area of the developed tumor. Similar NLS data were acquired for 38 patients who during a year's observation were diagnosed to have developed a tumor corresponding to phases II and III.

The NLS of the colon and straight intestine was performed a year before tumors were diagnosed in 21 patients affected by malignant polyps, of whom 17 had been under active observation because of polyposis, while no formation of that kind was in evidence during the initial examination. In addition, within the same time span 13 patients were examined who were diagnosed with a precan cerous condition (spectral similarity to straight intestine carcinoma, reference standard D>0.7) and minor forms of cancer. In 6 of the patients the tumor developed in the area of endoscopic polypectomy after they had a large villous adenoma removed. Thus, in 34 (27%) of 121 patients, who were diagnosed to have a malignant polyp condition in phase I or a small size tumor, colonic can cer developed within a year. 36 patients examined within the same time interval were found to have the conditions in phase II and III just as frequently. 28 of them were subjected to regular medical checkups with no clinical signs of the disease in evidence in any of them. 8 patients, within 37 months prior to tumor diagnosis, began to show signs of growing anemia or progressing stool retention. The dispensary observation data for these patients, with the NLS method employed a year before the cancer was detected, had indicated no tumor .

There are two very essential factors known to be of paramount importance for malignant disease diagnosis; they are the quality of clinical and diagnostic techniques and the specific pattern of the disease progress which actually determine the dynam ics of the disease progression. Considering the capabilities and working conditions in the therapeutic institutions, the presented data on gastric and colonic cancer diag noses may to a certain extent be regarded as optimum. It implies, that even if all the patients were readily diagnosed with the disease during the dispensary observation (actually it is a matter of 60%), the phase I condition could have been detected only in 40% of them. The analysis of causes of the late diagnosis cases suggests that such cases could be prevented by improving organizational and methodical work.

 Furthermore, the focus should be placed on the specific features of the disease progress which are of great, and possibly of vital importance for tumor detection. The analysis of the available data allows to assume that tumor may develop within a short time interval reaching the size of either "minor cancer" or extensive lesion. All that confirms the idea that the tumor growth dynam ics in different patients and in different phases of the disease is likely to vary and be of both continuous and discrete pattern. So a possible scenario of tumor development could be the emergence of "early" gastric cancer against the background of precancerous gastric diseases with a subsequent prolonged period of existence in the initial phase which allows to diagnose it after a year or a longer time later. At the same time, this "benign" scenario of disease progress is not typical for some patients and because of the rapid tumor growth we just fail to detect the initial phase of the condition in advance. The colonic cancer development through the benign phase and then through a malignant adenoma is not the only possible scenario it can proceed. Tumor can develop de novo and here too, a variant of a comparatively slow or fast growth is poten tial. This provides an explanation for an "accidental" detection of patients with fairly large tumors during dispensary observation and a great number of patients with a short clinical anamnesis and late phases of the disease.

Thus, NLS can be considered as an adequate method for diagnosing gas tric and colonic cancers. The difficulties in dealing with NLS interpretation largely concern the initial phases where the frequency of disease detection depends in the long run on how keen the physicians are on performing a spec tral verification of any focal changes in the mucosa in the case of a chronic gastritis and on keeping the patients under dynamic observation at the given modes of elimination and NLSanalysis involved. The submitted results allow to segregate two principal variants of the disease diagnosis. The first one sug gests "accidental" tumor detection during NLSinvestigation; neither clinical nor other familiar signs of disease are in evidence or their intensity is an insuf ficient reason for the patient to see a doctor. The second variant occurs when the patients develop clinical implications which impell the physician to carry out the respective investigations for them. The results of diacrisis of gastric and colonic cancers indicate that for most patients the problem of early diagnosis can not be solved, not only because of certain organizational factors but also and primarily because of the specific pattern of the disease progress and its manifestations. However, the actual opportunities for improving the well timed disease diagnosis in practical public health conditions lie, primarily, in increasing the number of patients to be examined by means of the NLS method within the frameworks of a health survey and also in a timely and complete examination of the patients who are suspected to have the disease.