Cancer Prevention and Early Diagnosis
It is well-known that preventing a disease is far less complex than trying to cure it. This principle applies to any disease, including cancer. Scientists from the world’s leading research centers are devoted to finding and defining all possible risk factors of developing cancer. By controlling the risk factors and minimizing their effect, we can significantly lower cancer incidence.
Cancer Risk Factors
The World Health Organization (WHO) defines risk factors as certain characteristics of individuals or the environment that increase the likelihood of one developing a disease.
Among scientifically proven risk factors of cancer, the following ones are the most proven:
- Infectious diseases - a number of infectious diseases cause structural changes in body tissues, which results in developing malignancies. In this regard, the following infectious agents are crucial: Hepatitis B virus (HBV) and hepatitis C virus (HCV), human immunodeficiency virus (HIV), human papillomavirus (HPV), Helicobacter Pylori and other bacteria. Treatment with modern antiviral, antibacterial, and antiparasitic drugs makes it possible to avoid severe complications of these commonly occurring infections.
- Premalignant benign conditions - some benign processes, such as cervical erosion, colon polyps, and inflammation of the esophagus, tend to malignant transformation. Early diagnosis and efficient therapy of premalignant conditions are able to neutralize the influence of this considerable risk factor of developing oncologic disease.
- Genetic mutations - thanks to the efforts of medical geneticists, multiple genetic risk factors of cancer have been discovered. For example, BRCA gene mutation increases the risk of developing ovarian and breast cancers. In some cases (for example, in Lynch syndrome and certain types of familial adenomatous polyposis), the chance of malignant transformation is near 100%. Timely diagnosis of these changes makes it possible to take efficient preventive measures, including preventive surgeries prior to malignization.
- Exposure to chemical agents - environmental pollution and exposure to household and industrial chemical cancerogens have led to a substantial increase in the incidence of lung cancer, cancer of upper respiratory airways, skin, blood, bladder and breast.Harmful effects of asbestos and benzene-containing aromatic compounds are well understood. Strict adherence to safety rules and recommendations for the use of household chemicals will contribute to the reduction of their harmful effects.
- Environmental exposure - effects of ultraviolet (solar radiation) and ionizing radiation are well known and extremely dangerous risk factors, significantly increasing the chance of developing such malignancies as melanoma (skin cancer) and blood cancers. High radiation levels caused by excessive radon concentration in building materials may cause lung cancer in people remaining in unventilated premises for long periods of time. Harmful radiation effects may be diminished by observing industrial hygiene and safety standards, as well as by applying sun-protection lotions or sunscreens and by reducing exposure to the sun.
- Poor nutrition - a balanced diet makes it possible to prevent many diseases, including malignancies. Lack of natural antioxidants, which are mainly found in fruits and vegetables, increases the risk of cancer. Fats are nutritional cancerogens, especially if they were repeatedly exposed to thermal agents. Moreover, there is indisputable proof of cancerogenic effects of some coloring substances and preservation agents widely used in the food processing industry.
- Obesity - a relation has been statistically proven between excess weight and esophagus, colon, breast, uterine and kidney cancers. Physical activity and maintaining a recommended body mass index are highly important from a preventive point of view.
- Alcohol consumption - alcohol intake has both local effect, which affects mucous membranes; and systemic effect, which increases the risk of cancer of the mouth, throat, larynx, esophagus, liver, colon and breast.
- Smoking - aside from the harmful effects of tobacco, active and passive smokers are exposed to cancerogenic resins that are found in tobacco products of any type. Quitting smoking will contribute substantially to lowering the risk of lung cancer in both smokers themselves and their close ones. Additionally, smoking has a proven effect on the incidence of cancer of lip and oral cavity, larynx, throat, esophagus, stomach, pancreas, cervix, and bladder.
Finally, it is essential to emphasize the importance of leading a generally healthy lifestyle in order to lower the risk of cancer as much as possible.
Modern Methods for Early Cancer Diagnosis
The overwhelming majority of malignant tumors can be treated successfully if detected early. Timely diagnosis of non-invasive cancer types makes it possible to limit the treatment to a relatively small procedure, allowing to preserve the affected organ, and to prevent side effects of systemic treatment. For the purpose of early diagnosis in oncology, physicians use screening that includes a number of laboratory tests and diagnostic procedures that can detect an asymptomatic tumor at its early stages. Screening tests are widely used in healthy populations of any age, as well as in people exposed to known risk factors.
Screening for Cancer
The following are the main screening methods Used:
- Tests for tumor markers - laboratory tests for biochemical and hormonal changes can be an indication of cancer presence in asymptomatic patients who have no complaints. Some tests for tumor markers, such as PSA screening test for prostate cancer, are recommended to all populations of a certain age and above.
- Genetic tests - indicated when physicians suspect gene mutations that increase the possibility of cancer (for example, diagnosis of Lynch syndrome). The BRCA1 and BRCA2 mutations test is of great importance to families of female patients with breast cancer, uterine cancer and ovarian cancer.
- Fecal occult blood test - determines the presence of even a minor gastric hemorrhage that may often be caused by cancer. The test is recommended for people over 50 years of age on a periodic basis, and in case of unexplained anemia in patients of any age.
- Papanicolaou (PAP) test and human papillomavirus (HPV) test - routine gynecological follow-up and screening diagnosis of cervical cancer are recommended to women aged 21 to 65 years old. These tests help detect both cancer and precancerous changes that can be treated successfully.
- Mammography (X-ray of the breast) - one of the most efficient methods to diagnose space-occupying lesions, including malignant tumors. Carried out on a regular basis in women of 40 to 74 years of age, mammography substantially reduces the probability of detecting cancer at late and inoperable stages. Mammography is often combined with an ultrasound examination to obtain the full presentation of the breast.
- Breast magnetic resonance imaging (MRI) - if BRCA1 and BRCA2 mutations are diagnosed, a detailed breasts assessment should be done. МRI can diagnose minor structural changes in tissues; it is done in compliance with experts’ recommendations.
- Transvaginal sonography - the method is indicated to female patients with Lynch syndrome and to those carry the BRCA1 and BRCA2 mutations, for timely diagnosis of malignant transformations in the ovaries and uterus.
- Low radiation computerized tomography protocol - this screening method is recommended for patients exposed to lung cancer risk factors, with smokers over 55 years of age among them.
- Endoscopic diagnostic methods - colonoscopy and gastroscopy allow doctors to detect in time cancer and premalignant conditions (polyps) of gastrointestinal tract. Diagnostic colonoscopy is recommended as a screening test for patients over 50 years of age who are in a higher than average risk group for colorectal cancer; it is also recommended for individuals of any age who have genetic factors.
- Virtual colonoscopy - modern medicine enables patients to undergo a detailed noninvasive colon examination using a special protocol of computed tomography. Even though the examination technique makes it impossible to take diagnostic biopsies of suspicious foci, it is truly indispensable in patients who have contraindications for conventional invasive colonoscopy.
- Skin examination and nevi mapping - dermatologic follow-up on a regular basis using modern optical diagnostic techniques contributes to timely skin cancer diagnosis, including melanoma – the most dangerous of skin cancers. Dermatologist’s assessment is recommended for each and every person with benign pigmentation disorders; mapping nevi on regular basis makes it possible to follow their growth dynamics and perform a timely excision.
Early Cancer Diagnosis is a Prerequisite of Successful Treatment
The treatment method, the patient survival rate, and the possibility of the full recovery are essential factors to determine in early cancer diagnosis. A 5-year survival rate from the date of cancer diagnosis is an important statistical value in oncology. As a rule, survival within this time indicates the full recovery or efficient control over tumor growth. The following are prognoses for some common cancer types:
- Lung cancer - Survival statistics is function of a tumor stage and its histological type: a 5-year survival was approximately 38% in patients newly diagnosed with Stage I small-cell lung carcinoma, while a 5-year survival was 73% in patients newly diagnosed with Stage I non-small-cell lung carcinoma. However, if the tumor is newly diagnosed at the stage of invasive growth and metastases, it reduces survival to 1% in case of small-cell lung carcinoma and to 9% in case of non-small-cell lung carcinoma.
- Breast cancer - Timely diagnosis and proper treatment of Stage I breast cancer make it possible to reach a 5-year survival of 90% and a 10-year survival of 85%. When Stage IV breast cancer is newly diagnosed, only 13% of patients may survive.
- Colon cancer - Diagnosed during screening, noninvasive cancer shows a survival rate of 93%. The survival percentage is reduced substantially as the tumor advances, and it comes to 6% only at Stage IV in patients with inoperable metastases, and to 40% in patients with metastases amenable to surgery.
- Stomach cancer - Early-stage stomach cancer rarely causes symptoms, and unfortunately, stomach cancer is rarely diagnosed at Stage I when a 5-year survival is about 80%. survival at Stage IV stomach cancer is less than 5%.
- Melanoma - The most aggressive form of skin cancer. Made at screening, visual control facilitates early diagnosis of melanoma. The full recovery at Stage I of melanoma is possible in 95% of cases, while survival at stage IV is 5% only.