Cancer: prevention and early detection
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Cancer has been a major epidemic for many years, being one of the diseases that causes the most deaths worldwide. There is also a geographic pattern in which countries with longer life expectancies have higher incidence rates of the disease, thus confirming its relationship with aging. According to data from the International Agency for Research on Cancer, approximately 18.1 million new cases of cancer were diagnosed worldwide in 2020. The same agency indicates that this figure could increase to 27 million around 2040, which represents a 50% increase over the next 20 years.
What is cancer?
The term cancer encompasses a heterogeneous group of diseases that all have one common characteristic: the uncontrolled growth of abnormal cells. This cell growth, if left untreated, can spread to different parts of the body and ultimately destroy tissues and organs. We call cancer a complex group of diseases because it varies depending on where it originates in the body, how the disease progresses, the genes affected, and so on. But in the vast majority of cases, there is always one common denominator: the earlier treatment is started, the more effective it will be. To achieve this, the key is early detection of the disease.
Cancer prevention and early detection
Much of cancer research focuses on identifying new biomarkers that can be used for early detection. Although there are currently population-based screening programs that use some of these newly discovered biomarkers to detect very specific types of cancer in their earliest stages, there is still a lack of tests that detect the risk of developing different types of cancer throughout life in a single test.
The causes of cancer are diverse and complex. In the vast majority of cases, external factors are responsible. Thus, continued exposure to certain environmental factors can eventually lead to the development of cancer. These factors are well known and include, among others:
- Smoking.
- Excessive alcohol consumption.
- Overweight.
- Physical inactivity.
- Contact with certain pathogens such as the human papillomavirus or Helicobacter pylori infection.
- Regular exposure to sunlight without proper protection.
- Regular exposure to certain chemicals.
Sporadic cancer prevention
In most of these cases, cancer will appear at an advanced age, after the age of 50, as it is the result of continued lifelong exposure to these environmental factors, which is known as sporadic cancer. As previously mentioned, there are several population-based screenings that allow for early detection of the disease. For example, in the Catalan health system, the entire population over the age of 50 is screened for colorectal cancer through fecal occult blood testing. There are also screenings for the early detection of prostate cancer through PSA protein determination in peripheral blood, or for 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 to the population in performing them, as they will detect many cases in which treatment is truly effective and the tests are noninvasive. Unfortunately, these 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
Aside from sporadic cancers, there are a number of cancers that have a hereditary origin. These types of cancer are usually differentiated from sporadic cancers because they tend to manifest at younger ages (in the 30s or 40s). Other characteristics of these types of cancer, which can help us suspect 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 cancers.
- Cancer develops bilaterally in paired organs (both breasts affected).
- Two or more cancers develop in different locations.
- Diagnosis of rare cancers (e.g., 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 life. This 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 contribute to this increased risk occur in genes with important functions such as growth control, cell division, or DNA repair. One of the best-known examples is the BRCA1 and BRCA2 genes , key in DNA repair mechanisms . Women who have variants in these genes have up to a 72% risk of developing breast cancer throughout their lifetime. This risk is six times higher than the population risk of breast cancer, which in Spain is around 12%.
Furthermore, men with a variant in the BRCA2 gene have a 60% lifetime risk of developing prostate cancer. This risk is five times greater than the population risk of 12%. It is estimated that approximately 1 in 400 people in the general population have a genetic variant in one of these two genes.
Genetic study for cancer prevention
The genetic test for cancer prevention is a screening test that determines whether we are at a higher risk of developing cancer than the general population. AboutMe’s cancer prevention program studies up to 12 different types of cancer and more than 10,000 genetic variants in 47 genes associated with hereditary cancer. Detecting any of these variants will allow us to access a series of preventive actions whose main objectives are to reduce the risk of developing cancer or 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 another measure will be applied, but following the examples mentioned above:
Breast cancer control guidelines
A woman identified as having a variant in the BRCA1 gene will be able to access measures to reduce her risk of developing cancer. Scientific studies show that prophylactic bilateral mastectomy reduces the risk of developing breast cancer by more than 90% in patients who carry genetic variants in the BRCA1 gene. Alternatively, early detection measures using imaging techniques are also available. In this specific case, annual mammography and breast MRI are recommended starting at age 30.
Detection of high risk of prostate cancer
Similarly, patients with the BRCA2 gene variant will be able to access specific noninvasive preventive medicine options, such as PSA protein testing starting at age 40 (10 years earlier than the recommended dose for the general population). This way, in both cases, a potential cancer could be treated with a high probability of success.
