Prevention of cancer

2021-02-06 12:00 AM

The suspicion of a link between smoking and cancer has been raised 200 years ago. The first report in 1795 has linked smoking and lip cancer.


Diagnosis and symptoms of many types of cancer have made great progress recently, but the number of people infected and died from cancer is still high and forecast to continue to increase in the coming time. If the cancer is cured, the financial and emotional consequences still cover the rest of the patient's life.

Epidemiologists have estimated that 70-80% of all cancers are due to environmental causes, so we can prevent cancer by preventing exposure to the causes. cancer. So, in theory, we have the ability to reduce morbidity and mortality from cancer by more than 80%.

Initial prevention (step one)

Primary prevention is to try, eliminate, or minimize exposure to causes of cancer. This is the most active preventive method.

Factors of cause and prevention


The suspicion of a link between smoking and cancer has been raised 200 years ago. The first report in 1795 has linked smoking and lip cancer. The first work in 1928 concluded that cancer is more common in smokers. In the 1950s studies in the UK and the United States demonstrated a causal link between smoking and lung cancer. Since 1960, smoking rates in the US, Canada, UK and Australia have decreased from 42% to 25%. However, according to World Health Organization statistics, smoking rates in developing countries have increased. average annual of about 8%.

Up to now, it has been found that tobacco causes 30% of all cancers, 90% of lung cancers, 75% of cancers of the oral cavity, larynx, oesophagus, and 5% of bladder cancers. Therefore, the physician must organize anti-smoking movements to propagate for drug addicts to gradually reduce to stop smoking.

Encourage current smokers to stop smoking.

Support the patient to stop smoking.

Organize periodic follow-up visit.

Pay attention to propaganda towards teenagers who have never smoked and for pregnant women.


Behind tobacco, many nutritional factors are ranked the second most important cause of cancer and death.

The typical Western diet and some developed countries high in meat and fat have been linked with colon cancer. Many recent studies have highlighted that the risk increases with a diet low in vegetables and fruits due to a lack of certain vitamins (A, C and E), micronutrients (selenium, iron), and fibre. in that diet.

In developing countries, aflatoxin, a product of mould in food, is the main cause of liver cancer; Nitrites and nitrates in smoked foods play a role in increasing the rate of cancer of the oesophagus and stomach.

Every effort to prevent cancer has turned towards changing a low-meat diet, increasing the intake of fruits, vegetables and vitamins especially beta-carotene. Avoid overeating, seasoning and eating mouldy foods.

Preventive Chemistry

Preventive chemistry is to drink a chemical, for example, vitamins to stop the carcinogenesis process. Preventive chemistry has only really grown rapidly in recent years. Many different chemicals are being used to evaluate the effectiveness of chemoprophylaxis: Retinoids and carotene, many antioxidants such as vitamins C and E, selenium, calcium, nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin, sulindac and tamoxifen, an anti-estrogen that has been widely used to treat breast cancer. In the United States, a randomized trial is aimed at preventing prostate cancer with finasteride, the 5-alpha reductase inhibitor.


There are 4 viruses known to cause cancer in humans: Hepatitis B virus, Epstein-Barr virus, Human papillomavirus (HPV) and T-leukemia virus in humans. (HTLV)

Hepatitis B along with aflatoxin infection is considered to be the cause of most primary liver cancer in African and Southeast Asian countries. Extensive newborn vaccination of hepatitis B has reduced the incidence and death of primary liver cancer.

Many vaccines are also circulating against the Epstein-Barr virus, which is considered a major cause of dome cancer and Burkitt lymphoma. The vaccines for HPV and HTLV are in the early stages.

Solar radiation

Ultraviolet (UV) radiation caused by excessive sun exposure is considered the main cause of skin cancer (with and without pigmentation), especially with light skin tones. Cancer rates are highest in Australia and Ireland. It is necessary to propagandize people to avoid excessive sun exposure, use sunshades (shirts, hats, hats), skin protection creams.

Occupational exposure

Occupational exposure is identified among the earliest known causes of cancer. The number of most known carcinogens is in the industrial field. For example, Asbestos is an occupational carcinogen that causes lung cancer and in the pleural tissue.

In most countries, industrial hygiene and labour protection are taken seriously to lower the incidence of occupational cancer patients.

Side effects of medication

Certain methods of diagnosis or treatment are also carcinogenic, especially with radiation and chemotherapy. Some hormones used for birth control or gynaecological treatment also have a risk of developing cancer later. For example, vaginal cancer in girls exposed to diethylstilbestrol is used by the mother in early pregnancy to reduce nausea and prevent a threatened miscarriage.

Clinicians need to pay attention to carcinogens, especially female hormones, anti-cancer substances with alkyl nuclei, must have a follow-up plan to detect secondary cancers caused by drug use. or inducing treatments.

Genetic factors

Long family history is also considered a common risk factor for some types of cancer such as breast cancer, colorectal cancer, retinal cancer, and dry pigmentation. Initial preventive strategies such as using Tamoxifen as a chemoprophylaxis test for women with a family history of breast cancer. In addition, one must also consider step two prophylaxis (screening program) for people with a family history of cancer.

Other risk factors

Ionizing radiation is also a risk factor for many forms of cancer, for example after the atomic bombing in Japan, or after the atomic reactor accident in Chernobyl.

A recently known cancer risk factor is that less physical activity, work, and leisure may help prevent colon cancer.

Many cancers are known to be associated with AIDS. Every measure to prevent AIDS is also an effort to prevent some cancers.

Screening and early detection of cancer (step two)

Screening is a way of assessing the entire population or individual clinically healthy, to detect an underlying or precancerous cancer so that it can be cured. Screening is based on the notion that early detection of cancer before metastasis occurs, is better than when symptoms appear.

Cancer is considered ideal for screening when its preclinical detectable stage is long before symptoms appear and metastasis occurs.

Breast cancer screening

Breast cancer is leading cancer among women in both developed and developing countries. Breast cancer screening has reduced this cancer mortality rate.

Screening methods include:

Clinical breast examination (CEB: Clinical Examination of the breast)

Is a common method to detect breast cancer. Specialists recommend an annual seasonal physical exam to all women over 40 as part of a comprehensive health checkup.

Breast self-examination (BSE: Breast Self - Examination)

It is an inexpensive and harmless technique for the mammary glands. Do a breast self-exam once a month after your period is cleared. If a woman is instructed to do a careful breast self-examination, she will find out that when the tumour is small, there are less metastatic lymph nodes than those who do not practice breast self-examination. Therefore, the method of self-examination of the breast should be widely disseminated on the mass media.

Mammography (Mammography)

This method has been technically mature in recent years and is widely used for early detection screening and breast cancer diagnosis.

For women over 40 years of age in the high-risk group should have an unprepared mammogram every year, women over 50 years of age mammography sensitivity exceed 85% and specificity is 95-99%.

Screening for cervical cancer

Squamous cell carcinoma of the cervix often follows an epithelial dysplasia and local cancer (CIN: Cervical intraepithelial neoplasia). Approximately 20% of the above lesions develop into invasive cancer within 20 years. Also detectable by a detachable cell test. Cervical cancer can thus be prevented if the screening is done with the correct Pap test or vaginal cytology once or twice a year in married women over 30 years old.

Cervical cytology is an effective way to prevent invasive cervical cancer and death from cervical cancer. In countries with the Pap test cervical cancer screening program, the rate of invasive cervical cancer cases has decreased by 30%.

In localities that do not have the means to do Pap test, it is possible to examine the cervix with speculum for women over 30 years old. If detecting any suspected lesions, they will be referred to a specialist clinic for diagnosis and treatment.

An eye examination can be combined with a Lugol colposcopy test to magnify cervical lesions, cervical apical removal to both diagnose and treat pre-invasive cancers.

Screening for colon and rectal cancer

In many developed countries, colorectal cancer ranks second after lung cancer. Since the clinical symptoms are often not obvious, patients come to the examination at a relatively late stage. However, with the emergence of many types of colorectal cancer screening tests, it is theoretically ideal to diagnose the disease before symptoms appear.

The screening strategy should target high-risk populations and focus on ages 50-70.

Screening tests

Fecal occult blood tests (FOBT: Fecal occult blood tests).

Detection of peroxidase activity of haemoglobin. Screening tests show approximately 2% of FOBT positive and the expected value of the test for both benign and cancerous adenomas between 20-30%. False positives from food and drugs have also occurred.


Colonoscopy S (Sigma) up to 20cm has been used as a test alone or in combination with FOBT. Colonoscopy has the advantage of high sensitivity and specificity and visibility of the entire colon frame but high cost and risk of perforation (20/00 colonoscopy cases) limit screening. follow this method. Full colonoscopy should only be performed on high-risk subjects with a positive FOBT test.

Screening for other cancers


This type of cancer can well screen for risk factors such as family history, history of sunburns or freckles, and moles on the body. The main screening method is the eye exam and meticulous examination with well-trained health workers.

Lung cancer

There is no evidence to suggest that lung cancer screening with chest x-ray and phlegm cytology affects mortality, but annual routine chest x-rays for smokers over 45 years old do can detect lung tumours as a child.

Dome cancer

Screened by measuring the IgA antibodies of the Epstein-Barr virus in areas with high incidence.

Cancer of the mouth and mouth

Subjects with the habit of chewing tobacco and chewing betel, smoking and drinking alcohol were all at high risk. Clinical screening combined with educational programs for the general population has contributed to the early detection of cancer and precancerous conditions.

Stomach cancer

Gastroscopy and gastroscopy screening programs have been highly appreciated in Japan.

The limitation of screening is high cost, so it should apply to the high-risk group (age, history of chronic gastric ulcer).

Primary liver cancer

Screening by measuring and alpha Foetoprotein in serum of subjects already infected with hepatitis B.

Ultrasound is used to monitor cases of abnormal results.

Prostate cancer

3 tests that can detect the disease when there are no symptoms are manual rectal examination, rectal ultrasound, prostate-specific antigen.

Thyroid Cancer

Subjects that have been irradiated into the head and neck area are at high risk. They need to be periodically examined and tested with calcitonin and Thyroglobulin.


Screening to detect cancer in the absence of symptoms often has positive results for some types of cancer: breast, cervical, stomach, colon, and melanoma. To be effective, screening must reduce mortality and reduce mortality caused by screening programs depending on the development of universal health programs.