Did you know that up to 10% of cancer cases are caused by inherited genetic changes?
This surprising fact shows the importance of understanding hereditary cancer.
It is key to know its causes and how to prevent it.
Cancer is a complex disease, but genetic predisposition is key in some types.
Inherited gene mutations increase the risk of certain cancers.
For example, breast, ovarian, colon and prostate cancer.
These mutations are found in the eggs or sperm and are passed on to the offspring.
Thus, some inherited cancer syndromes affect several people in a family.
Knowing your family history of cancer and doing genetic testing is key.
This can determine your risk and help you take preventative measures.
Thanks to advances, there are now strategies such as surveillance, chemoprevention and prophylactic surgery.
These can save lives.
What is hereditary cancer?
Hereditary cancer occurs when inherited genetic mutations increase the risk of certain cancers.
About 5% of cancers are of this type.
About 50 genes related to hereditary predisposition to cancer have been identified.
Definition and characteristics of hereditary cancer
Hereditary cancer is distinguished by several traits.
In families with this type of cancer, it is common to see several cases of the same type at a young age.
For example, in breast/ovarian and colorectal syndrome, cancers usually appear between the ages of 40 and 50.
In hereditary cancer, bilaterality is also seen in paired organs and multiple primary tumors.
In addition, developmental defects may occur.
Differences Between Hereditary Cancer and Sporadic Cancer
Hereditary cancer is distinguished from sporadic cancer.
Most cancers are sporadic, caused by somatic mutations and environmental risk factors .
In contrast, hereditary cancer is due to an inherited germline mutation.
| Characteristic | Hereditary cancer | Sporadic cancer |
|---|---|---|
| Proportion of cases | About 5% | Most of cases (95%) |
| Age of onset | Earliest (40-50 years) | Advanced age |
| Main causes | Inherited genetic mutations | Somatic mutations, environmental and lifestyle factors |
| Risk of developing cancer | High risk conferred by germline mutations | Risk influenced by multiple factors |
If signs of familial cancer are observed, it is key to consult a Family Cancer Unit.
These units offer genetic counseling and perform genetic testing.
Although it is not always possible to identify inherited mutations, there are recommendations for the management of cancer predisposition syndromes.
Understanding the differences between hereditary and sporadic cancer is key.
This helps implement early detection strategies and appropriate management in individuals and families at high risk for cancer.
Genetic causes of hereditary cancer
Alterations in specific genes cause hereditary cancer.
These genes, like tumor suppressors, control cell growth.
If they mutate, the risk of cancer increases.
Mutations in cancer susceptibility genes
Mutations in BRCA1 and BRCA2 cause hereditary breast and ovarian cancer syndrome.
Mutations in MLH1, MSH2, and MSH6 cause Lynch syndrome.
These mutations are inherited, explaining cancer in certain families.
Inheritance patterns in families with hereditary cancer
Most hereditary cancer syndromes follow an autosomal dominant inheritance.
This means that only one mutated copy of the gene needs to be inherited to increase the risk of cancer.
However, not everyone who inherits the mutation develops cancer.
Variable expressivity indicates that the age of onset and severity of cancer vary among family members.
Major hereditary cancer syndromes and associated genes
Some of the most common hereditary cancer syndromes include:
- Hereditary breast and ovarian cancer syndrome (BRCA1 and BRCA2 genes)
- Lynch syndrome or hereditary nonpolyposis colorectal cancer (MLH1, MSH2, MSH6, PMS2 genes)
- Familial adenomatous polyposis (APC gene)
- Li-Fraumeni syndrome (TP53 gene)
Each syndrome has a specific spectrum of associated cancers and requires individualized management strategies.
The following table shows some relevant data about these syndromes:
| Syndrome | Associated genes | Related cancers | Risk of developing cancer |
|---|---|---|---|
| Hereditary breast and ovarian cancer syndrome | BRCA1, BRCA2 | Breast, ovarian, prostate, pancreatic cancer | Up to 75% for breast cancer, 40-60% for ovarian cancer |
| Lynch Syndrome | MLH1, MSH2, MSH6, PMS2 | Colorectal, endometrial, ovarian, stomach, small intestine, pancreatic, urinary tract, brain | Cancer Up to 70-80% for colorectal cancer, 40-60% for endometrial cancer |
| Familial adenomatous polyposis | APC | Colorectal, duodenal, thyroid, hepatoblastoma cancer | Almost 100% for colorectal cancer if left untreated |
| Li-Fraumeni syndrome | TP53 | Soft tissue sarcomas, osteosarcoma, breast, brain, adrenal cancer, leukemia | Up to 90% lifetime risk of developing cancer |
Diagnosis of hereditary cancer
Diagnosing hereditary cancer is key and requires a detailed evaluation of family history.
The aim is to identify specific clinical criteria .
Then, they are referred to Family Cancer Units for specialized genetic counseling.
These units assess individual risks, offer psychological support , and manage the family implications of hereditary cancer.
Identifying Families with Possible Hereditary Cancer
Screening for families with hereditary cancer begins with a family history review.
Warning signs such as multiple cases of cancer, early onset, and bilaterality are sought.
Specific clinical criteria are also established to identify families who need further evaluation.
| Criteria | Description |
|---|---|
| Multiple cases of cancer in the family | Presence of several relatives with the same or related cancers |
| Onset at an early age | Diagnosis of cancer in relatives before the age of 50 |
| Bilaterality | Development of cancer in both paired organs (e.g., both breasts or both ovaries) |
| Multiple primary tumors | An individual with more than one type of primary cancer |
Family Cancer Units and Genetic Counseling
The Family Cancer Units have specialists in genetic counseling.
They carry out a personalized risk assessment for each member of the family.
They offer information about the likelihood of developing cancer and early detection strategies.
They also address the emotional and family implications of hereditary cancer, providing psychological support.
Genetic Testing and Its Interpretation
Genetic testing is key to detecting mutations in risk genes.
However, it is not always possible to perform them due to the lack of knowledge about all the genes responsible.
It is important to perform them in recognized laboratories and interpret the results by experts.
It is crucial to discuss the implications of the results and ensure the confidentiality of genetic information.
| Hereditary cancer syndrome | Associated gene(s) | Lifetime cancer risk |
|---|---|---|
| Hereditary Breast and Ovarian Cancer Syndrome | BRCA1, BRCA2 | Breast: 50-85%, Ovarian: 15-45% |
| Lynch syndrome | MLH1, MSH2, MSH6, PMS2 | Colorectal: 50-80%, Endometrium: 40-60% |
| Familial adenomatous polyposis | Colorectal APC | : close to 100% if left untreated |
| Li-Fraumeni syndrome | TP53 | Sarcomas, breast, brain, adrenal: 90% |
Hereditary Cancer Prevention and Management
Preventing and managing hereditary cancer requires a comprehensive approach.
This includes medical surveillance, chemoprevention, and prophylactic surgery.
These strategies follow clinical practice guidelines and require a multidisciplinary health team.
Regular medical surveillance
Early detection is key to the management of hereditary cancer.
Those at high risk should have frequent exams and tests.
These recommendations come from clinical practice guidelines and require a team of experts.
Chemoprevention and prophylactic surgery
Chemoprevention, which uses drugs to prevent cancer, is being studied.
Prophylactic surgery, such as mastectomy, can reduce the risk of cancer.
But, these decisions must be well thought out and consider the preferences of each person.
Implications for at-risk family members
If a genetic mutation is found, it affects family members.
It is key to offer them genetic counseling and testing.
Communicating this type of information can be difficult, so health professionals offer support.
It is important to remember that genetic discrimination is illegal in many countries.
