Why you cannot be tested for all types of cancer at once - oncologist debunks a popular myth
Medicine is full of myths. One of the most common is the belief that you can screen your entire body for all types of cancer at once. Oncologists say they frequently encounter such requests. Tengrinews.kz set out to discover which screenings actually help detect tumors at an early stage and which ones are a waste of time.
"There is no single test that can rule out all types of cancer"
Screening programs were introduced in Kazakhstan to improve early cancer detection. However, they are only implemented when major studies demonstrate that these tests effectively lead to earlier diagnoses, timely treatment, and, ultimately, a reduction in mortality rates.
So far, only a few effective screening programs have been developed for certain types of cancer, explained Elena Ukolova, a clinical oncologist and chemotherapist whom we contacted for comment.
"You can't just undergo a maximum number of tests; you need to approach the process sensibly. In fact, there is no single blood test, procedure, or 'cancer check-up' that can rule out all types of malignant tumors," the expert explained.
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Elena Ukolovaclinical oncologist, chemotherapist
About the speaker: Elena Ukolova is an oncologist specializing in the medicinal treatment of malignant neoplasms and a participant in international educational programs in oncology. In her practice, she adheres to the principles of evidence-based medicine and works to popularize scientifically grounded information about oncological diseases.
For instance, there are currently no universal methods for the early detection of pancreatic, ovarian, or brain cancer.
Cancer Screenings: Which tests help detect cancer
Cervical Cancer
According to Elena Ukolova, cervical cancer is one of the few types of cancer that, in many cases, can not only be detected at an early stage but also prevented altogether. This is because the disease is preceded by precancerous changes that can be identified and treated in a timely manner.
The specialist recommends screening for:
Women aged 21 and older — a Pap test (cytological examination of cervical cells) every three years;Aged 30 and older — a high-risk human papillomavirus (HPV) test every five years or co-testing (Pap test combined with an HPV test).
The oncologist noted that in Kazakhstan, government screening is provided free of charge to women aged 30–70. A Pap test is performed once every four years at their local clinic..
"If high-risk HPV, dysplasia, or other changes are detected, doctors determine the further observation schedule on an individual basis," she added.
Breast Cancer
Mammography is the only screening method that has proven effective in reducing breast cancer mortality.
"I recommend starting screening at age 40, every one to two years (the interval depends on recommendations from various international organizations and individual risk factors)," Elena Ukolova explained.
In Kazakhstan, women aged 40–70 can also undergo mammography screening free of charge once every two years..
"In the presence of hereditary syndromes (for example, mutations in BRCA1, BRCA2, or PALB2), specialists use a different monitoring strategy. This may include starting screening at a younger age, breast MRIs, and more frequent examinations," she specified.
Note: BRCA1, BRCA2, and PALB2 are the names of human genes that help cells repair damaged DNA and protect the body from the development of certain types of cancer. Colorectal Cancer
Elena Ukolova points out that colorectal cancer is also among the diseases that can be both detected early and prevented.
For example, during a colonoscopy, a doctor can find and remove polyps (small growths on the mucous membrane of internal organs) before they have the chance to transform into a malignant tumor.
"Starting at age 45, you should have a colonoscopy every 10 years. Alternatively, you can take a FIT (Fecal Immunochemical Test) annually—a modern immunological analysis of stool for occult blood," the specialist said.
If the test results are positive, a colonoscopy is mandatory.
In Kazakhstan, free government screening is available to women and men aged 50 to 70. A FIT test is used for this purpose once every two years..
"For patients with Lynch syndrome, familial adenomatous polyposis, or a significant family history, screening begins much earlier and is conducted more frequently," the expert noted.
Note: Lynch syndrome is a hereditary condition where genetic mutations significantly increase the risk of developing colorectal cancer, as well as cancers of the endometrium, stomach, ovaries, and several other organs. Familial adenomatous polyposis (FAP) is a rare hereditary disorder characterized by the development of hundreds or even thousands of polyps in the colon. If left untreated, the risk of developing colorectal cancer is extremely high.
Lung Cancer
Next is lung cancer. It is the leading cause of cancer-related mortality worldwide and remains one of the most common causes of cancer deaths in Kazakhstan.
Currently, the only screening method proven to effectively reduce mortality from this disease is low-dose computed tomography (LDCT).
The doctor recommends this screening for:
individuals aged 50 to 80;those who have smoked at least one pack of cigarettes a day for 20 years;current smokers;and those who quit smoking less than 15 years ago.
However, according to the specialist, people without risk factors should not undergo a standard chest CT "just in case.".
"This type of screening is not yet part of the state program, but the issue is already under discussion," the expert noted.
Photo: depositphotos.com
Prostate Cancer
Unlike the previous types of cancer, the situation with prostate cancer screening is not as clear-cut, the oncologist says.
"The primary method is the prostate-specific antigen (PSA) test, which measures a protein produced by prostate cells. However, this test can detect not only clinically significant tumors but also slow-growing forms of cancer that would never have impacted the patient's life expectancy," our speaker explained.
In other words, these tumors are so "indolent" that a person would likely live with them for their entire life and die of another cause, never knowing they existed.
Therefore, according to the physician, there is currently no universal screening for all men. However, an examination can be considered:
from age 50 — after discussing the benefits and limitations of the test with a doctor;from age 45 — in the presence of high-risk factors (such as a family history).
"But the decision to undergo testing must be made together with a doctor, after discussing the benefits and potential risks," she clarified.
Stomach Cancer
As Elena Ukolova noted, in many countries, endoscopic gastric examination (EGD) is not included in mass screening programs. However, in Japan and South Korea, this approach has already proven its ability to reduce mortality.
According to the specialist, this disease is still quite common in Kazakhstan.
The doctor recommends discussing a preventive gastroscopy with a physician if a person has one or more risk factors:
age over 50;
Helicobacter pylori infection;atrophic gastritis;intestinal metaplasia;family history of stomach cancer.
Skin and Oral Cavity
Although these examinations are not included in the state screening program, the oncologist considers them an important part of prevention:
"Skin cancer is the most common cancer in the world, and melanoma is one of the most aggressive tumors."
According to her, people with a large number of moles, fair skin, or a family history of melanoma should be particularly attentive to their skin. The doctor recommends they see a dermatologist.
The expert also advises using sunscreens with SPF and regularly performing skin self-exams using the international ABCDE rule to monitor moles:
A (Asymmetry): asymmetry in shape.
B (Border): irregular, blurred, or jagged edges.
C (Color): uneven color (brown, black, red, or blue within a single mole).
D (Diameter): diameter exceeds six millimeters (though melanomas can be smaller).
E (Evolution): any changes — growth, itching, bleeding, or change in shape.
"One should not forget about preventive dental check-ups. They help in detecting changes in the oral mucosa early on, especially for smokers and those who abuse alcohol," she emphasized.
Why it is impossible to be tested for all types of cancer
If effective methods for the early detection of certain tumors exist, why can't we perform one comprehensive screening to check the entire body?
The doctor explained that in oncology, the principle of "the more tests, the better" does not apply. Every diagnostic method has its limitations as well as its advantages.
"The more tests performed on a person without complaints or risk factors, the higher the probability of finding incidental changes that pose no health risk but require further investigation. As a result, the patient has to undergo repeat CT scans, MRIs, and biopsies, experiencing severe stress and sometimes even undergoing unnecessary treatment," our speaker explained.
Therefore, doctors do not recommend undergoing numerous examinations without clinical indications.
Which screenings are unsuitable for "cancer checks" — a doctor on common mythsTumor markers
According to Elena Ukolova, one of the most common mistakes is believing that tumor markers can confirm or rule out cancer in a healthy person.
"Very often patients come in asking: 'I want to test for all tumor markers to make sure I don't have cancer.' But unfortunately, it doesn't work that way," she emphasized.
Tumor markers are substances whose levels may increase in certain types of cancer. However, their concentration can also rise due to completely different conditions: inflammation, infections, liver disease, endometriosis, prostate adenoma, and so on.
"Even in the presence of a malignant tumor, tumor marker levels can remain perfectly normal, especially in the early stages of the disease. Therefore, today, no widely used tumor marker is recommended for screening healthy individuals," the doctor explained.
In practice, according to Elena Ukolova, they are used for other purposes:
to assess treatment effectiveness;to monitor how a patient responds to therapy;to follow up after the completion of treatment for certain tumors;occasionally as a supplementary diagnostic method if a doctor already suspects a disease.
Complete blood count and biochemistry
Another common myth is that cancer can be detected through a blood test.
According to the doctor, some tumors can indeed be accompanied by anemia, an increased ESR, or changes in white blood cell counts. However, the same changes occur in many other diseases.
"And vice versa. Many patients with early-stage cancer have normal test results. Therefore, neither a complete blood count nor a biochemical blood test serves as a method for cancer screening," Elena Ukolova clarified, debunking the myth.
Photo © Tengrinews.kz / Marzhan Kuandykova
Whole-body CT, MRI, and PET-CT
As mentioned earlier, "full cancer check-ups" — examinations that include whole-body CT or MRI — have become increasingly popular in recent years.
However, Elena Ukolova reminds us that there is currently no convincing evidence that such screenings help reduce cancer mortality in healthy individuals.
On the other hand, they often reveal changes that pose no danger: small cysts, benign growths, or anatomical variations. To ensure they are safe, the patient must undergo additional testing.
"Furthermore, computed tomography involves radiation exposure, and PET-CT is not used at all for the preventive screening of healthy people. Therefore, experts do not advise undergoing whole-body CT, MRI, or PET-CT without medical indications," the oncologist said.
Note: PET-CT (Positron Emission Tomography combined with Computed Tomography) is an imaging method that simultaneously shows the structure of organs and how they function.
Common mistakes patients make
Another misconception is thinking that after receiving good screening results, the risk of cancer is eliminated. According to Elena Ukolova, even if a screening revealed nothing, it is essential to consult a doctor if new complaints arise:
"Even the highest quality screening does not have 100% sensitivity. The appearance of new symptoms always requires a separate evaluation by a doctor, regardless of previous test results."
Reasons for seeking medical attention should include:
unexplained weight loss;blood in stool, urine, or phlegm;prolonged changes in bowel habits;unusual spotting or bleeding;a lump in the breast or any other part of the body;changes to a mole (growth, changes in color or shape, bleeding);a cough persisting for more than several weeks, especially in smokers;persistent difficulty swallowing;any symptoms that progress or persist despite treatment.
"Screenings are performed on asymptomatic individuals. If symptoms are already present, we are no longer talking about screening, but diagnostics, and the scope of the examination is determined by entirely different principles," the expert explained.
Another mistake frequently noted by the physician is that people undergo numerous tests annually while postponing truly effective examinations for years:
"For example, mammograms, colonoscopies, or Pap tests. Yet these are the ones that currently have the most compelling evidence base."
Finally, the specialist advises against waiting for alarming symptoms to disappear on their own. Even if a person has recently undergone screening with good results, this does not rule out the possibility of disease.
What helps reduce cancer risk
Vaccination
The physician considers vaccination to be one of the most effective ways to prevent certain types of cancer.
Quitting smoking
According to the specialist, about 85–90 percent of lung cancer cases are linked specifically to tobacco use. Smoking also increases the likelihood of developing cancer of the mouth, larynx, esophagus, bladder, pancreas, kidneys, stomach, cervix, and several other organs.
Lifestyle
It is well-established today that many habits directly influence cancer risk, noted Yelena Ukolova.
For instance, overweight and obesity are linked to an increased risk of at least 13 types of cancer, including endometrial, postmenopausal breast, colorectal, esophageal, liver, and kidney cancers.
As a reminder, every second adult in Kazakhstan is overweight or obese.
Conversely, regular physical activity helps reduce the risk of colorectal and breast cancer.
The physician specifically draws attention to alcohol. According to her, there is no safe dose of alcohol in terms of cancer prevention. Even moderate consumption is associated with an increased risk of breast, liver, esophageal, and gastrointestinal cancers.
"There is no single test that can rule out all types of cancer"
Screening programs were introduced in Kazakhstan to improve early cancer detection. However, they are only implemented when major studies demonstrate that these tests effectively lead to earlier diagnoses, timely treatment, and, ultimately, a reduction in mortality rates.
So far, only a few effective screening programs have been developed for certain types of cancer, explained Elena Ukolova, a clinical oncologist and chemotherapist whom we contacted for comment.
"You can't just undergo a maximum number of tests; you need to approach the process sensibly. In fact, there is no single blood test, procedure, or 'cancer check-up' that can rule out all types of malignant tumors," the expert explained.
Add quote author
Add image
Elena Ukolovaclinical oncologist, chemotherapist
About the speaker: Elena Ukolova is an oncologist specializing in the medicinal treatment of malignant neoplasms and a participant in international educational programs in oncology. In her practice, she adheres to the principles of evidence-based medicine and works to popularize scientifically grounded information about oncological diseases.
For instance, there are currently no universal methods for the early detection of pancreatic, ovarian, or brain cancer.
Cancer Screenings: Which tests help detect cancer
Cervical Cancer
According to Elena Ukolova, cervical cancer is one of the few types of cancer that, in many cases, can not only be detected at an early stage but also prevented altogether. This is because the disease is preceded by precancerous changes that can be identified and treated in a timely manner.
The specialist recommends screening for:
Women aged 21 and older — a Pap test (cytological examination of cervical cells) every three years;Aged 30 and older — a high-risk human papillomavirus (HPV) test every five years or co-testing (Pap test combined with an HPV test).
The oncologist noted that in Kazakhstan, government screening is provided free of charge to women aged 30–70. A Pap test is performed once every four years at their local clinic..
"If high-risk HPV, dysplasia, or other changes are detected, doctors determine the further observation schedule on an individual basis," she added.
Breast Cancer
Mammography is the only screening method that has proven effective in reducing breast cancer mortality.
"I recommend starting screening at age 40, every one to two years (the interval depends on recommendations from various international organizations and individual risk factors)," Elena Ukolova explained.
In Kazakhstan, women aged 40–70 can also undergo mammography screening free of charge once every two years..
"In the presence of hereditary syndromes (for example, mutations in BRCA1, BRCA2, or PALB2), specialists use a different monitoring strategy. This may include starting screening at a younger age, breast MRIs, and more frequent examinations," she specified.
Note: BRCA1, BRCA2, and PALB2 are the names of human genes that help cells repair damaged DNA and protect the body from the development of certain types of cancer. Colorectal Cancer
Elena Ukolova points out that colorectal cancer is also among the diseases that can be both detected early and prevented.
For example, during a colonoscopy, a doctor can find and remove polyps (small growths on the mucous membrane of internal organs) before they have the chance to transform into a malignant tumor.
"Starting at age 45, you should have a colonoscopy every 10 years. Alternatively, you can take a FIT (Fecal Immunochemical Test) annually—a modern immunological analysis of stool for occult blood," the specialist said.
If the test results are positive, a colonoscopy is mandatory.
In Kazakhstan, free government screening is available to women and men aged 50 to 70. A FIT test is used for this purpose once every two years..
"For patients with Lynch syndrome, familial adenomatous polyposis, or a significant family history, screening begins much earlier and is conducted more frequently," the expert noted.
Note: Lynch syndrome is a hereditary condition where genetic mutations significantly increase the risk of developing colorectal cancer, as well as cancers of the endometrium, stomach, ovaries, and several other organs. Familial adenomatous polyposis (FAP) is a rare hereditary disorder characterized by the development of hundreds or even thousands of polyps in the colon. If left untreated, the risk of developing colorectal cancer is extremely high.
Lung Cancer
Next is lung cancer. It is the leading cause of cancer-related mortality worldwide and remains one of the most common causes of cancer deaths in Kazakhstan.
Currently, the only screening method proven to effectively reduce mortality from this disease is low-dose computed tomography (LDCT).
The doctor recommends this screening for:
individuals aged 50 to 80;those who have smoked at least one pack of cigarettes a day for 20 years;current smokers;and those who quit smoking less than 15 years ago.
However, according to the specialist, people without risk factors should not undergo a standard chest CT "just in case.".
"This type of screening is not yet part of the state program, but the issue is already under discussion," the expert noted.
Photo: depositphotos.com
Prostate Cancer
Unlike the previous types of cancer, the situation with prostate cancer screening is not as clear-cut, the oncologist says.
"The primary method is the prostate-specific antigen (PSA) test, which measures a protein produced by prostate cells. However, this test can detect not only clinically significant tumors but also slow-growing forms of cancer that would never have impacted the patient's life expectancy," our speaker explained.
In other words, these tumors are so "indolent" that a person would likely live with them for their entire life and die of another cause, never knowing they existed.
Therefore, according to the physician, there is currently no universal screening for all men. However, an examination can be considered:
from age 50 — after discussing the benefits and limitations of the test with a doctor;from age 45 — in the presence of high-risk factors (such as a family history).
"But the decision to undergo testing must be made together with a doctor, after discussing the benefits and potential risks," she clarified.
Stomach Cancer
As Elena Ukolova noted, in many countries, endoscopic gastric examination (EGD) is not included in mass screening programs. However, in Japan and South Korea, this approach has already proven its ability to reduce mortality.
According to the specialist, this disease is still quite common in Kazakhstan.
The doctor recommends discussing a preventive gastroscopy with a physician if a person has one or more risk factors:
age over 50;
Helicobacter pylori infection;atrophic gastritis;intestinal metaplasia;family history of stomach cancer.
Skin and Oral Cavity
Although these examinations are not included in the state screening program, the oncologist considers them an important part of prevention:
"Skin cancer is the most common cancer in the world, and melanoma is one of the most aggressive tumors."
According to her, people with a large number of moles, fair skin, or a family history of melanoma should be particularly attentive to their skin. The doctor recommends they see a dermatologist.
The expert also advises using sunscreens with SPF and regularly performing skin self-exams using the international ABCDE rule to monitor moles:
A (Asymmetry): asymmetry in shape.
B (Border): irregular, blurred, or jagged edges.
C (Color): uneven color (brown, black, red, or blue within a single mole).
D (Diameter): diameter exceeds six millimeters (though melanomas can be smaller).
E (Evolution): any changes — growth, itching, bleeding, or change in shape.
"One should not forget about preventive dental check-ups. They help in detecting changes in the oral mucosa early on, especially for smokers and those who abuse alcohol," she emphasized.
Why it is impossible to be tested for all types of cancer
If effective methods for the early detection of certain tumors exist, why can't we perform one comprehensive screening to check the entire body?
The doctor explained that in oncology, the principle of "the more tests, the better" does not apply. Every diagnostic method has its limitations as well as its advantages.
"The more tests performed on a person without complaints or risk factors, the higher the probability of finding incidental changes that pose no health risk but require further investigation. As a result, the patient has to undergo repeat CT scans, MRIs, and biopsies, experiencing severe stress and sometimes even undergoing unnecessary treatment," our speaker explained.
Therefore, doctors do not recommend undergoing numerous examinations without clinical indications.
Which screenings are unsuitable for "cancer checks" — a doctor on common mythsTumor markers
According to Elena Ukolova, one of the most common mistakes is believing that tumor markers can confirm or rule out cancer in a healthy person.
"Very often patients come in asking: 'I want to test for all tumor markers to make sure I don't have cancer.' But unfortunately, it doesn't work that way," she emphasized.
Tumor markers are substances whose levels may increase in certain types of cancer. However, their concentration can also rise due to completely different conditions: inflammation, infections, liver disease, endometriosis, prostate adenoma, and so on.
"Even in the presence of a malignant tumor, tumor marker levels can remain perfectly normal, especially in the early stages of the disease. Therefore, today, no widely used tumor marker is recommended for screening healthy individuals," the doctor explained.
In practice, according to Elena Ukolova, they are used for other purposes:
to assess treatment effectiveness;to monitor how a patient responds to therapy;to follow up after the completion of treatment for certain tumors;occasionally as a supplementary diagnostic method if a doctor already suspects a disease.
Complete blood count and biochemistry
Another common myth is that cancer can be detected through a blood test.
According to the doctor, some tumors can indeed be accompanied by anemia, an increased ESR, or changes in white blood cell counts. However, the same changes occur in many other diseases.
"And vice versa. Many patients with early-stage cancer have normal test results. Therefore, neither a complete blood count nor a biochemical blood test serves as a method for cancer screening," Elena Ukolova clarified, debunking the myth.
Photo © Tengrinews.kz / Marzhan Kuandykova
Whole-body CT, MRI, and PET-CT
As mentioned earlier, "full cancer check-ups" — examinations that include whole-body CT or MRI — have become increasingly popular in recent years.
However, Elena Ukolova reminds us that there is currently no convincing evidence that such screenings help reduce cancer mortality in healthy individuals.
On the other hand, they often reveal changes that pose no danger: small cysts, benign growths, or anatomical variations. To ensure they are safe, the patient must undergo additional testing.
"Furthermore, computed tomography involves radiation exposure, and PET-CT is not used at all for the preventive screening of healthy people. Therefore, experts do not advise undergoing whole-body CT, MRI, or PET-CT without medical indications," the oncologist said.
Note: PET-CT (Positron Emission Tomography combined with Computed Tomography) is an imaging method that simultaneously shows the structure of organs and how they function.
Common mistakes patients make
Another misconception is thinking that after receiving good screening results, the risk of cancer is eliminated. According to Elena Ukolova, even if a screening revealed nothing, it is essential to consult a doctor if new complaints arise:
"Even the highest quality screening does not have 100% sensitivity. The appearance of new symptoms always requires a separate evaluation by a doctor, regardless of previous test results."
Reasons for seeking medical attention should include:
unexplained weight loss;blood in stool, urine, or phlegm;prolonged changes in bowel habits;unusual spotting or bleeding;a lump in the breast or any other part of the body;changes to a mole (growth, changes in color or shape, bleeding);a cough persisting for more than several weeks, especially in smokers;persistent difficulty swallowing;any symptoms that progress or persist despite treatment.
"Screenings are performed on asymptomatic individuals. If symptoms are already present, we are no longer talking about screening, but diagnostics, and the scope of the examination is determined by entirely different principles," the expert explained.
Another mistake frequently noted by the physician is that people undergo numerous tests annually while postponing truly effective examinations for years:
"For example, mammograms, colonoscopies, or Pap tests. Yet these are the ones that currently have the most compelling evidence base."
Finally, the specialist advises against waiting for alarming symptoms to disappear on their own. Even if a person has recently undergone screening with good results, this does not rule out the possibility of disease.
What helps reduce cancer risk
Vaccination
The physician considers vaccination to be one of the most effective ways to prevent certain types of cancer.
Quitting smoking
According to the specialist, about 85–90 percent of lung cancer cases are linked specifically to tobacco use. Smoking also increases the likelihood of developing cancer of the mouth, larynx, esophagus, bladder, pancreas, kidneys, stomach, cervix, and several other organs.
Lifestyle
It is well-established today that many habits directly influence cancer risk, noted Yelena Ukolova.
For instance, overweight and obesity are linked to an increased risk of at least 13 types of cancer, including endometrial, postmenopausal breast, colorectal, esophageal, liver, and kidney cancers.
As a reminder, every second adult in Kazakhstan is overweight or obese.
Conversely, regular physical activity helps reduce the risk of colorectal and breast cancer.
The physician specifically draws attention to alcohol. According to her, there is no safe dose of alcohol in terms of cancer prevention. Even moderate consumption is associated with an increased risk of breast, liver, esophageal, and gastrointestinal cancers.