Is breast cancer hereditary? Are sisters and daughters of breast cancer at greater risk of developing cancer? How to prevent and treat it early?
These questions are often asked by many people in clinical practice. Because of the lack of knowledge about the heredity of breast cancer and some bad information exaggerating the genetic factor in the process of breast cancer, some breast cancer patients often have self-blame and self-hate psychology, some female immediate family members of breast cancer patients (such as sisters and daughters) feel a lot of pressure, and some female family members blindly or even over-tested and treated.
Recent studies have been able to answer these questions: breast cancer, like most malignant tumors, occurs due to a combination of environmental and genetic factors. Genetic factors account for only a small part of the mechanism of breast cancer development. Some studies have shown that only about 5% of hereditary breast cancers have been found to have a clear causative agent, accounting for only a small percentage of all breast cancer patients. The majority of breast cancers are clinically acquired and do not have a clear genetic predisposition.
First of all, it is important to have a proper understanding about the concepts related to heredity of breast cancer (hereditary factors of tumors, hereditary breast cancer, familial breast cancer, and people at high risk of hereditary predisposition to breast cancer). How are malignant tumors (breast cancer, for example) inherited? Half of the genetic material of a child comes from the father and half from the mother. If either parent has a defect in the genetic material, it may be passed on to the child.
There are three ways of tumor inheritance.
1. Hereditary familial tumor syndrome (cancer family , single gene inheritance, accounting for ≤ 1% of total incidence). Breast cancer does not have this mode of inheritance.
2. Genetic susceptibility to tumors (familial cancer).
In most cases, hereditary tumors are inherited only by the susceptibility of tumors, i.e. susceptibility genes, and if somatic mutations occur in the individual susceptible state, the mutated cells will be easily transformed into tumor cells. These “susceptibility genes” and how they function are not well understood. Although the mode of inheritance of these cancers is not well understood, it has been shown that some tumors run in families, or that family members have an increased susceptibility to these tumors, and that the incidence is usually 3-4 times higher in first-degree relatives of patients than in the general population. Hereditary breast cancer belongs to this category, but the percentage of all breast cancers is only 5-10%.
3. Localized genetic alteration of tumor cells (acquired). Most clinical breast cancers belong to this type.
Familial breast cancer refers to a type of breast cancer with family aggregation. In other words, if two related members of a family have breast cancer, it can be called familial breast cancer. Breast cancer with a clear genetic predisposition is called hereditary breast cancer. This type of breast cancer accounts for 5-10% of the entire breast population and is characterized by early age of onset, bilateral onset and multicentric lesions. Most hereditary breast cancers are familial in nature; however, a small percentage of hereditary breast cancers are sporadic in distribution and have no family history. This may be because the mutated genes associated with breast cancer are carried by male family members who are unable to develop a breast cancer phenotype. Most hereditary breast cancers are associated with breast cancer susceptibility genes (BRCA-1, BRCA-2). Nowadays, in addition to BRCA-1 and BRCA-2, p53 and PTEN are known. Breast cancers associated with mutations in these genes are classified as hereditary breast cancers. As with all hereditary breast cancers, the majority of BRCA-1 and BRCA-2 associated breast cancers are familial, with a proportion presenting sporadically.
What types of breast cancers are likely to be hereditary in patients?
Hereditary breast cancer has certain characteristics, often manifesting as early onset, familial aggregation, etc. Early onset refers to the early age of onset of breast cancer, which may be less than 35 years old; familial aggregation refers to the fact that two or more members of the family are breast cancer patients, sometimes combined with other malignant tumors, such as ovarian cancer, prostate cancer, stomach cancer, etc.
People who are at risk of breast cancer in the family are
1. The age of onset is less than 35 years old.
2. In addition to the first patient found to have breast cancer in the family, there is at least one or more first or second degree relatives who have breast or ovarian cancer.
3.The first patient in the family to be found to have breast cancer is a bilateral breast cancer.
4. the first patient in the family to be found to have breast cancer also has or has had ovarian cancer
5. The first patient in the family to be found to have breast cancer is a male with breast cancer.
What should I do if I have a high suspicion of hereditary breast cancer or if it is clear that I have hereditary breast cancer?
The biggest problem is that healthy members of the family who are related to the patient may also carry the disease-causing gene mutation, and women who carry these mutations have a much higher lifetime risk of developing breast cancer, for example, the BRCA1 and BRCA2 genes, the lifetime risk of cancer in mutation carriers is as high as 60-70%. It is recommended that people at high risk who meet the conditions of family genetic predisposition should be tested for mutations in breast cancer susceptibility genes. The age of screening for healthy women who are highly suspected or clear carriers of the mutation needs to be advanced by at least 10 years. Screening using diagnostic breast imaging is generally recommended starting around the age of 25 to 30. Since the application of mammography screening is often ineffective in young women due to dense breast tissue, studies have shown that the application of magnetic resonance imaging (MRI) is essential in early breast screening in high-risk women. Hereditary breast cancer is not scary, it is a small percentage of all breast cancers, what is important is to detect its hereditary nature and it is very important to seek timely medical attention.