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In addition to prophylaxis, early detection of cancer is of key importance in the reduction of mortality in some neoplastic diseases. Screening tests make it possible.
Screening tests are diagnostic activities carried out on healthy people, but at a higher risk of developing a specific neoplasm (e.g. in certain age groups). They are aimed at the early detection of a tumor or even a precancerous condition.
A good screening test should have certain characteristics, the most important of which are high sensitivity and specificity. Sensitivity is the ability to detect neoplasm – the higher it is, the fewer neoplasms go undetected (false-negative results). Specificity is a feature of the ability to detect healthy people – the higher it is, the fewer healthy people are identified as sick (false positive results).
For screening to achieve its goal, screening must be carried out on as many people as possible who are at increased risk and, importantly, for many years. For this to happen, you need appropriate funds each year and social awareness that you need to apply for such research on a regular basis.
Screening only makes sense for cancers with a high prevalence in the population and for which there is an effective treatment. A large-scale search for a rare neoplasm would incur huge costs with disproportionately small social benefits. The decline in mortality would be small, and money would be used that could be used to treat many other diseases. The same is true for cancers for which there are no effective medical procedures. What will result in their early detection if the disease cannot be cured?
Cost is an important limiting factor in screening. It is clearly visible when comparing the recommendations of American and European oncology societies. However, one should not jump to conclusions, because the results of ongoing studies evaluating specific methods do not always confirm the advisability of more frequent and more expensive screening tests.
Breast cancer:
For the early detection of breast cancer, the following has been proposed for years: self-examination of the breast, examination by a doctor and mammography.
The purposefulness of the first two methods in the light of recent studies is debatable due to the low sensitivity (only nodules of the appropriate size are palpable, not all areas on the breast are available in the examination, and it is difficult for the woman to assess whether the self-examination has been performed correctly). Despite these inconveniences, self-examination is a manifestation of conscious interest in health, because a woman who undergoes regular examinations knows that with each detected change, she should immediately consult a doctor, which in turn results in early diagnosis of the observed changes.
The downside of manual breast examination (both performed by the woman herself and by a doctor) is insufficient specificity – in such an examination it is practically impossible to distinguish potentially malignant lesions from benign ones. Nevertheless, both methods are recommended as adjuncts to mammography.
Mammography is a test the value of which is established by many years of clinical observation and has been added to the list of screening tests. It is recommended in different countries to start mammography at a different age and the frequency of testing varies. For example, the American Cancer Society recommends an annual mammogram for women over 40, while the UK program includes screening for women aged 50-64 every 3 years. Clinical trials have shown that regular mammography is most effective in reducing breast cancer mortality (by approx. 30%) in women between 50 and 69 years of age.
Researchers are constantly wondering when to start and when to stop using mammography. Some believe that screening should be started from the age of 40, although the incidence of breast cancer in women aged 40-50 is relatively low. Prior mammography should be considered in women with risk factors for breast cancer. However, in the 50-69 age group, increasing the frequency of mammography (once a year instead of once every 3 years) does not bring any noticeable benefits. In the case of people over 70 years of age further mammograms only make sense in people who are not suffering from other life-limiting diseases. The expected benefits for each patient should be considered individually.
Some people are concerned that regular mammograms may carry a risk of cancer, but they are not scientifically confirmed. Theoretically, such a risk may exist among women carriers of the BRCA1 and BRCA2 genes, for whom earlier mammography is recommended, even from the age of 25, because the repair of radiation DNA damage may be impaired as a result of a genetic mutation.
Colon cancer:
Colorectal cancer screening tests include a fecal occult blood test (this test detects traces of blood that do not change the color of the stool), and if positive, sigmoidoscopy, colonoscopy or radiographs. Endoscopic examinations (sigmoidoscopy and colonoscopy) involve the insertion of a flexible tube equipped with optical devices through the anus and enable visual assessment of the walls of the large intestine. The sigmoidoscope reaches a distance of up to 60 cm, while the colonoscope allows you to examine the entire colon. It is possible to take specimens for histopathological examination to confirm the diagnosis. These tests allow not only to detect early intestinal tumors, but also to remove small changes that are precancerous conditions.
In the United States, people over 50 years of age occult blood testing is recommended once a year, sigmoidoscopy every 5 years, two-contrast X-ray examination of the intestine and colonoscopy every 5-10 years.
Colonoscopy seems to be the most effective method. However, it is expensive, not always fully effective, and often not accepted by patients.
Cervical cancer
Cervical smear smear test is the best example of an effective screening test. With the correct collection of the material and its proper evaluation, the sensitivity and specificity are significant.
This test is relatively cheap and effective. In some countries, it has reduced the mortality rate from cervical cancer by as much as 70%. In the United States, annual screening is recommended for women in their 20s or from sexual activity to old age. However, for financial reasons, this standard was not adopted in Europe. Nevertheless, even less frequent cytodiagnosis in women over 30 years of age. causes a significant decrease in mortality from cervical cancer.
important:
Possible symptoms of neoplastic disease
• constant headache
• epilepsy
• enlarged lymph nodes
• hoarseness or trouble swallowing for more than 3 weeks
• a lump in the breast or a deformation of the skin on its surface
• constant cough, blood clotting disorders, shortness of breath
• nipple discharge
• changes in pigmented nevi
• enlarged abdominal circumference
• defecation rhythm disturbances
• postmenopausal bleeding
• vaginal discharge
Other worrying symptoms:
• loss of appetite
• weight loss
• anemia
The downside to manual breast examination is insufficient specificity. In such an examination, it is practically impossible to distinguish potentially malignant from benign lesions.
Worth knowing:
How do I look for free screening tests?
Free tests for selected neoplastic diseases – breast cancer (mammography), cervical cancer (cytology) and colon cancer (colonoscopy) – are financed by the National Health Fund or by the Ministry of Health. Some are conducted throughout the country, some only in selected voivodeships. If you want to check which of the preventive programs are carried out in a given voivodeship, contact the appropriate branch of the Fund or ask your primary care physician about it. In the same places, you can also find out the criteria that must be met to take part in the free trial, as well as receive a list of health care facilities that conduct them. People who meet all the criteria can apply for tests without a referral – only a document confirming insurance is needed.
Text: lek. med. Tomasz Figiel
Source: Let’s live longer