- Igor Vladimirovich Pershukov is a professor, Doctor of Medical Sciences and Philosophy (PhD), head of the Department of Hospital Therapy with a course in Radiation Diagnostics and Oncology at Jalal-Abad State University, as well as a fellow of the American College of Cardiology (FACC) and the American Society of Cardiovascular Angiography and Interventions (FSCAI).
We present to you the main points:
“Modern oncology emphasizes primary prevention of malignant tumors, the goal of which is to reduce morbidity.
It is important to distinguish between individual and state initiatives in cancer prevention.
Individual Prevention
This includes informing citizens about cancer and adhering to a number of recommendations.
Everyone should remember the risk factors that contribute to the development of malignant tumors:
- About rational nutrition. It is necessary to exclude salty and pickled products containing nitrites and nitrates from the diet. Instead of canning, freezing is preferable. This has contributed to a decrease in stomach cancer incidence in the USA. It is recommended to limit the consumption of animal fats, fried and smoked foods, and to increase the intake of fresh vegetables and fruits. During periods of shortage of fresh products, taking synthetic vitamins is beneficial. Clinical observations show that vitamins A and E can reduce the risk of gastric epithelial metaplasia and positively influence precancerous changes in the mucosa;
- About the harm of smoking, both active and passive. Quitting smoking can reduce cancer risk by 30%;
- About endocrine-metabolic disorders. Obesity and frequent abortions increase the risk of reproductive system cancer;
- About hereditary forms of cancer. Consultation with a specialist is necessary for "familial forms" of cancer;
- About the harm of excessive sun exposure;
- About maintaining hygiene standards concerning the oral cavity and genital organs;
- About the harm of excessive alcohol consumption. Low-alcohol beverages, such as table wines, are less dangerous.
Mass Prevention
State initiatives in primary cancer prevention involve controlling the content of carcinogens and radioactive substances in drinking water, food, air, and soil. The government needs to address environmental issues by developing and implementing filters for enterprises that pollute the air, improving the efficiency of internal combustion engines, and using eco-friendly fuels.
Timely diagnosis at early stages allows for the treatment of 70-100% of patients with malignant tumors of most organs.
The foundation of early diagnosis is screening. Its goal is to reduce mortality by actively identifying and treating preclinical forms of cancer. Screening programs must meet several criteria:
- The pathology being studied must be socially significant with high morbidity and mortality;
- The screening method must have high sensitivity, although specificity is less critical;
- Accessibility of the method for the general population;
- Minimal cost and invasiveness of the procedure;
- The reduction of mortality from this pathology should be a result of screening.
Considering these conditions, several oncological diseases have been selected for the creation of screening programs: breast cancer, cervical cancer, stomach cancer, colorectal cancer, prostate cancer, and lung cancer.
However, there are objective obstacles to the widespread implementation of screening.
In the Russian Federation, a breast cancer screening program using mammography is being implemented. According to it, women aged 40-60 are screened every two years in one projection.
However, there are problems with this program. Randomized studies have shown that the optimal age for mammographic screening is 50-69 years, as most cases of the disease occur at ages 60-64. It is also recommended to conduct mammography annually and in two projections. For women aged 40-49, screening can be conducted every two years. The necessity of screening in the group aged 70 and older is a subject of debate. Studies have shown that screening reduces mortality from breast cancer by 25% in the age group of 50-69 years. Breast ultrasound is used to clarify the diagnosis, not as a screening method. Self-examination has not yet shown a significant impact on mortality reduction, and women practicing it should follow the same recommendations for regular mammography as everyone else. In the USA, thanks to screening, localized forms of breast cancer are diagnosed in 90% of women, while in Russia this figure is only 30%.
Cervical cancer screening, which began in the 1960s in Scandinavia, became effective due to cytological examination of cervical smears. This examination significantly reduces mortality from this form of cancer. The optimal interval between tests is 3 years, leading to a 90% reduction in mortality. Increasing the frequency to annual examinations yields only a 1% increase. The five-year survival rate for advanced cervical cancer does not exceed 13%, while for localized forms it is 88%. Thus, colposcopy should become a mandatory part of state preventive measures.
Esophagogastroduodenoscopy (EGDS) as a method for screening stomach cancer has shown effectiveness only in Japan, where the five-year survival rate at early stages reaches almost 100%. However, similar results have not yet been achieved in other countries. The USA is implementing stomach cancer screening, but results are currently lacking.
Colorectal cancer screening is carried out by detecting hidden blood in stool. The effectiveness of this method is confirmed by numerous studies showing a 33% reduction in mortality with annual screenings for individuals over 50 years old. Research is ongoing regarding the use of colonoscopy as a screening method, but results have not yet been published. Nevertheless, many insurance companies in the USA refuse to renew contracts with individuals over 50 who have not undergone colonoscopy.
Previously, chest X-rays and cytological examination of sputum were used for lung cancer screening, but randomized studies did not confirm a reduction in mortality. Thus, X-rays are only useful for monitoring tuberculosis. Currently, low-dose spiral computed tomography (CT) is being tested, which in Japan allows for the early diagnosis of lung cancer in 80% of patients, but the cost of this method remains an important issue.
For diagnosing prostate cancer in men over 50, the prostate-specific antigen (PSA) test is widely used. Since the early 1980s, prostate cancer incidence has sharply increased in the USA and Europe, but data on reduced mortality is lacking. The increase in incidence is attributed to the detection of latent forms that do not progress and do not threaten life, leading to a wait-and-see approach—patients are regularly monitored, and treatment begins only in the case of progression.
Thus, the effectiveness of screening has been confirmed for:
- Breast cancer using mammography in women aged 50-69;
- Precancerous and cervical cancer using colposcopy;
- Precancerous and colorectal cancer using the hidden blood test.
In the study phase are:
- Prostate cancer screening using the PSA test;
- Breast cancer in women under 50;
- Stomach cancer using EGDS;
- Lung cancer using spiral CT;
- Other methods.
Self-examination of the breasts and chest X-rays are not considered effective screening methods.
To improve early diagnosis and reduce mortality from oncological diseases, it is also necessary to train specialists, expand population coverage through individual invitations, promote information in the media, and monitor the program with an assessment of its effectiveness. A minimum effective coverage is considered to be 60% of the target population. In Scandinavia, this figure reaches 90% for breast and cervical cancer screening, while in Russia it is only 20%.
A key role in the timely diagnosis of malignant tumors is played by "oncological vigilance" among the population and the qualifications of doctors, especially at the primary level. It is necessary to actively promote knowledge about preventive examinations and early symptoms of malignant diseases. Unfortunately, insufficient qualification of medical personnel leads to many cases of late diagnosis. Additionally, alternative treatment methods, often carried out by unqualified specialists, can exacerbate the situation.”
