Cancer has been a major epidemic for many years now, being one of the diseases that contributes the highest mortality worldwide. There is also a geographical pattern in which countries with a longer life expectancy present higher values of incidence of the disease, thus confirming its relationship with ageing. According to data from the International Agency for Research on Cancer, in 2020 approximately 18.1 million new cases of cancer were diagnosed worldwide. The same agency points out that this figure could increase to 27 million around the year 2040, which represents an increase of 50% in the next 20 years.
What is cancer?
The term cancer encompasses a heterogeneous group of diseases that have one characteristic in common and that is the uncontrolled growth of a group of abnormal cells. Such cell growth, if left untreated in some way, can spread to different parts of the body and ultimately destroy tissues and organs. We say that cancer is a complex group of diseases since it presents differences in where it originates in the organism, how the disease evolves, the affected genes, etc. But in the vast majority of cases there is always a common denominator and that is that the earlier the treatment is started, the more effective it will be. For this, the key is early detection of the disease.
Cancer prevention and early detection
Much of cancer research focuses on the determination of new biomarkers that serve us for early detection. Although there are currently population screening programs that use some of these discovered biomarkers to detect very specific types of cancer at their earliest stage, there is still a lack of evidence that detects the risk of developing different types of cancer throughout life in a test only.
The causes that cause the appearance of cancer are diverse and complex. In the vast majority of cases, external factors are responsible. In this way, continued exposure to certain environmental factors can lead us to develop cancer at a given moment. These factors are well known and include among others:
- Excessive consumption of alcohol.
- Physical inactivity.
- Contact with certain pathogens such as the human papillomavirus or Helicobacter pylori.
- Regular exposure to sunlight without proper protection.
- Regular exposure to certain chemicals.
Sporadic cancer prevention
In most of these cases, the cancer will appear at an advanced age, after the age of 50, since it is the result of continuous exposure throughout life to these environmental factors, which is called sporadic cancer. As previously mentioned, there are a series of population screenings that allow early detection of the disease. For example, in the Catalan health system, the entire population over 50 years of age is screened for colorectal cancer by studying fecal occult blood. There are also screenings for the early detection of prostate cancer by determining the PSA protein in peripheral blood or breast cancer in women using imaging techniques such as mammography or magnetic resonance imaging. Although these screenings can present false negatives and false positives, there is a direct benefit at the population level in carrying them out, since many cases will be detected in which the treatment will be really effective and the tests are not invasive. Unfortunately, such preventive medicine strategies do not exist for all types of cancer and are limited to those cases in which there is an analyzable biomarker associated with a specific tumor type.
Hereditary cancer prevention
Leaving aside cases of sporadic cancer, there are a number of cancers that have a hereditary origin. These types of cancer are usually differentiated from sporadic ones since they tend to manifest at earlier ages (30s or 40s). Other characteristics of these types of cancer, and that can help us suspect that we are dealing with a hereditary case, are the following:
- Several members of a family develop the same type of cancer. Or they develop cancers that may be genetically related, such as breast and prostate.
- Cancer develops bilaterally in paired organs (both breasts affected).
- Two or more cancers develop in different locations.
- Diagnosis of rare cancers (for example: breast cancer in men).
Thus, in these cases, the affected person inherits a genetic variant or mutation from one of their two parents that predisposes them to developing cancer throughout their lives. It is what we know as hereditary cancer and it is estimated that up to 10% of all cancers correspond to this group. The inherited genetic variants that carry this increased risk occur in genes with important functions such as growth control, cell division, or DNA repair. One of the best-known examples are the BRCA1 and BRCA2, claves en los mecanismos de reparación del ADN. Women with variants in these genes have up to a 72% risk of developing breast cancer throughout their lives. This risk is 6 times higher than the population risk of breast cancer, which in Spain is around 12%.
In addition, men who have a variant in the BRCA2 gene have a 60% risk of developing prostate cancer throughout their lives. A risk that multiplies by 5 the population risk, which is 12%. It is estimated that approximately 1 in 400 people in the general population have a genetic variant in one of these two genes.
Cancer prevention genetic study
The genetic test for cancer prevention is a screening test that allows us to determine if we present a higher risk than the population risk of developing cancer. In the case of AboutMe cancer preventions we study up to 12 different types of cancer and more than 10,000 genetic variants in 47 genes associated with hereditary cancer. The detection of any of these variants will allow us access to a series of preventive actions whose main objectives will be to reduce the risk of developing cancer or to detect it early.
What to do if you have a high risk of hereditary cancer
Depending on the type of cancer in which the risk is increased, one or the other measures will be applied but following the examples mentioned above:
Breast cancer control guidelines
A woman who is identified with a variant in the BRCA1 gene will be able to access measures to reduce the risk of cancer onset. Scientific studies show that prophylactic bilateral mastectomy reduces the risk of developing breast cancer in patients carrying genetic variants in the BRCA1 gene by more than 90%. Alternatively, early detection measures can also be accessed through techniques of image. In this specific case, it would be recommended to perform a mammography and a breast nuclear magnetic resonance annually from the age of 30.
Detection of high risk of suffering from prostate cancer
Similarly, the patient who presents the variant in the BRCA2 gene will be able to access specific preventive and non-invasive medicine actions such as the determination of the PSA protein from the age of 40 (10 years before what is recommended at the population level). In this way and in both cases a possible cancer could be treated with a high probability of success.