The issue of cancer prevention is extremely important, and is amply and thoroughly dealt with in the publications and pamphlets of scientific societies, patients’ associations and healthcare institutions. All this material is available online, and the reader is advised to consult some of these websites for a complete treatment of the subject.
www.esmo.org/guidelines/;
https://www.nccn.org/professionals/physician_gls/default.aspx#detection
However, when faced with a huge amount of information, we may become confused and uncertain as to what exactly we should do. For this reason, this section provides only a summary of the “ABC” of prevention – a set of basic rules that everyone should follow; clinical studies conducted over several decades have demonstrated that these rules are effective.
Prevention can be divided into two separate areas:
- primary prevention, which means avoiding exposure to carcinogens, i.e. substances or agents that cause cancer;
- secondary prevention, which is based on the possibility to detect cancer early, at an initial stage when it is still curable by means of surgery alone.
1. With regard to primary prevention, by far the most important recommendation is “Don’t smoke”. However, it’s not just a question of whether or not we smoke; more important is how much we smoke and how long we have smoked. There is a simple way to calculate how much we have smoked in our lives by using the formula “packets of cigarettes/years”; this involves multiplying the number of 20-cigarette packets smoked each day by the number of years of smoking at that rate. For example, someone who smokes 1 packet a day for 20 years has a consumption of “20 packets/years”, which is the same as smoking half a packet for 40 years or 2 packets for 10 years. The table below shows the frightening increase in the risk of developing lung cancer as the consumption of cigarettes increases.
| Cigarette consumption (packets/years) | Risk of lung cancer |
|---|---|
| 1 | 0.1% |
| 20 | 1% |
| 60 | 5% |
| 90 | 8% |
| 100 | 13% |
| 120 | 20% |
So, 1 out of every 7 or 8 people (13%) who started smoking 2 packets of cigarettes a day at the age of 20 years will develop lung cancer at the age of 70. This is appalling. But there is some good news, too; when we give up smoking, this alarming risk begins to diminish steadily, and over time declines to very low levels, almost as low as those seen in non-smokers.
The recommendation not to smoke is followed, in order of importance, by the recommendations to limit alcohol consumption, excessive exposure to the sun, and exposure to asbestos and other toxic industrial materials.
Adopting a so-called “Mediterranean” diet also plays an important role in reducing the incidence of tumors, especially those of the gastrointestinal tract. Following this sort of diet involves reducing our consumption of red meat (though it’s not necessary to cut it out altogether), replacing red meat with white meats (fish, chicken) and, especially, eating plenty of fruit and vegetables. However, we can’t calculate the effect of diet mathematically; unlike the case of smoking, there is no formula of “hamburgers/years”!
Questions regarding issues such as the carcinogenic effect of mobile telephones, electricity power cables, pollution levels in the city, as opposed to the country, are difficult to answer, as the scientific evidence is insufficient. Here, common sense should prompt us to avoid extreme situations that might be harmful.
2.Secondary prevention is effective in the case of 4 types of tumor (but not all tumors). It involves carrying out instrumental examinations, which are repeated at intervals over time, starting from a certain age.
With regard to the recommendations for secondary prevention, we often come across two opposite attitudes. Some people become obsessed and continually request these examinations even when they are unnecessary, while other people just do nothing, either because they think it is not “a priority” or because they have not fully understood the problem.
As shown by the indications below (taken from the international guidelines, which are the result of painstaking clinical experimentation over the years), these preventive measures are remarkably effective. The number and frequency of these examinations, and the ages at which they should be carried out, are precisely indicated, and these indications should be followed to the letter. Notably, there are no recommendations for tests of tumor markers, given their scant reliability.
Cancer of the uterine cervix
Cervical cancer can be diagnosed early by means of the PAP TEST; this test should be carried out once every 3 years from the beginning of sexual activity to the age of 65 years. If the PAP test is positive, the woman needs to undergo colposcopy, which is an examination that enables the uterine cervix to be directly inspected visually. If this examination arouses suspicion, a biopsy will be taken.
From the age of 30 years upwards, an alternative to the PAP test is the new screening test for high-risk HPV infection. As in the PAP test, a swab sample is taken; this is then analyzed for the presence of HPV. If the HPV test is positive, a PAP test is done and the steps described above are followed.
Regarding the prevention of this type of tumor, we should also note that vaccination against the HPV virus is very effective; it is recommended for all individuals of school age and, in HPV-positive cases, also in adulthood.
Cancer of the colon and rectum
These cancers can be prevented very effectively through the diagnosis of polyps, which can be detected years before they develop into cancer. Prevention utilizes various strategies. In increasing order of both efficiency and difficulty, the following three are most often recommended:
- testing for hidden traces of blood in the feces, every 2 years between the ages of 50 and 70 years. If the test is positive, it is essential to carry out colonoscopy, which enables the entire colon and rectum to be examined. Colonoscopy allows a diagnosis to be made; in addition, any polyps that are found can be removed during the same session.
- in addition to this minimum program, or as an alternative to it, rectosigmoidoscopy should be carried out once between the ages of 55 and 65 years. Rectosigmoidoscopy is similar to colonoscopy, but is less uncomfortable for the patient, as it visualizes only the last part of the intestine (the sigmoid colon and the rectum). Indeed, 70% of colorectal tumors are found in this segment of the intestine. Rectosigmoidoscopy does not therefore explore the upper part of the colon.
- the most challenging examination, but also the most complete, is colonoscopy; this should be carried out for the first time at the age of 50 years, and then repeated 10 and 20 years later. Colonoscopy is the most effective preventive strategy, as it examines the entire organ.
Thanks to colonoscopy, deaths due to colorectal cancer can be reduced by up to 40%.
So-called virtual colonoscopy (a particular kind of CT scan in which no instruments are inserted into the body) is not so effective. However, if it proves positive, a “classic” colonoscopy will need to be carried out in any case.
Breast cancer
Early diagnosis is possible by means of mammography, which is recommended every 2 years between the ages of 50 and 70 years. A more demanding schedule involves extending mammography to women aged from 45 to 74 years, with an annual frequency in women under 50.
If the results of the first mammography arouse suspicion, a clinical examination is scheduled, further diagnostic tests are carried out and, if necessary, a biopsy is taken.
Thanks to screening, breast cancer deaths can be reduced by 25%.
Lung cancer
Finally, the efficacy of chest CT in reducing lung cancer mortality has very recently been demonstrated. This examination should be carried out once a year for 3 consecutive years after the age of 55 years. However, its efficacy, and therefore its recommendation, is not applicable to non-smokers, but only to current smokers or ex-smokers who have smoked at least a packet of cigarettes a day for 30 years or more, and who are therefore at high risk. Screening by means of chest CT enables lung cancer deaths to be reduced by about 20% in this population.