Hereditary cancer syndrome is caused due to mutation in genes. This article explains this syndrome in detail.
Cancer is known to happen when there is an abnormal growth of cells, and it is also called family cancer syndrome or cancer syndrome. It is genetically inherited where there may be a mutation of one or more genes. A syndrome is usually known to happen when there is a combination of various conditions. There can be lifetime risk, but also, there can be the development of numerous independent tumors.
Most of this combination of conditions occurs due to mutation that happens in tumor suppressor genes. Tumor suppressor genes help protect cells by inhibiting the transformation of normal cells into cancerous cells. Apart from these, various other genes might be affected, like the DNA repair genes, genes that take part in blood vessel formation, oncogenes, etc. Some commonly seen examples of inherited cancer syndromes are hereditary breast-ovarian syndrome, Lynch syndrome, etc.
The prevalence rate of this cancer is 5 to 10% of all the known cancers. It has nearly 50 variants, and there are over 50 identifiable hereditary forms of cancer. Certain rare cancers have shown an association with hereditary cancer predisposition syndromes.
Since there is a genetic predisposition, the gene mutation can show any of the following variations:
1. Mendelian Cancer Syndromes: It can be either autosomal dominant or autosomal recessive
2. Defective DNA Repair: It can present as autosomal recessive or autosomal dominant.
3. Familial Cancers: In this, the transmission pattern is not established yet.
a) DOMINANTLY INHERITED CANCER SYNDROMES:
In this, there can be an inheritance of one single mutant gene. Only one gene can be mutated. Some examples are:
Retinoblastoma: There is a mutation of the RB tumor suppressor gene. It is usually bilateral and has more risk of forming second cancer.
Familial Adenomatous Polyposis: In this, there is a mutation of the APC Tumor suppressor gene.
Li-Fraumeni Syndrome: There is a germline mutation of the p53 gene, which increases the chances of getting breast tumors, brain tumors, sarcomas, childhood adrenocortical carcinomas, and acute Leukemias
MEN1 and 2: In MEN1, there is an increased risk for forming parathyroid tumors, pancreatic tumors, and/or pituitary tumors.
In MEN2, there is a mutation of RET proto-oncogene. It causes an increased risk of developing medullary thyroid cancers. Also, the person has an increased risk of developing pheochromocytoma, parathyroid tumors, and/or mucosal neuromas involving the lips and tongue.
This condition can be classified and diagnosed based on the family history and medical history, followed by clinical examination of the patient and genetic testing.
Hereditary Nonpolyposis Colorectal Cancer: This puts a patient at a high risk of developing cancers involving the colon, ovary, endometrium, stomach, small intestine, and bile duct.
Von Hippel-Lindau Disease: It is clinically characterized by abnormal growth of blood vessels in various parts of the body. Hemangioblastomas and angiomas may develop in such patients. Various body parts that can be involved are the retinas, spinal cord, certain areas of the brain, adrenal glands, and other parts of the body.
Neurofibromatosis Type 1: This typically affects the Schwann cell.
Peutz-Jeghers Syndrome: Multiple polyps within GIT develop along with cutaneous pigmentation around lips, oral mucosa, face, genitalia.
Cowden Syndrome: This creates an increased risk of breast and thyroid cancers.
Familial Melanomas: CMM1, CMM2, (CDKN2), CDK4 genes are involved in this type of tumor. Almost 5 to 7% of patients come from genetically high-risk families. There is a presence of invasive melanoma in at least two first-degree relatives. Some people have nearly 10 to 100 moles on the upper trunk and limbs.
b) CANCERS DUE TO DEFECTIVE DNA REPAIR:
The major drawback of a defective DNA repair is DNA instability. Some of the autosomal recessive conditions include:
Xeroderma Pigmentosum: In this, there is a defect in the excision stage of repair. The main damage is due to UV radiation.
Bloom’s Syndrome: In this, there is a defect in the repair enzymes DNA ligase 1. It causes an increased risk of forming all types of cancers.
Ataxia-telangiectasia: This includes a defect in the repair of gamma radiation damage to nucleotide bases.
c) FAMILIAL CANCERS:
Though the exact representation of this type of cancer is not known, there is an increased risk to first-degree relatives. The major contributing factors are inter-relation marriages and environmental factors like lung cancer. Some of the more commonly seen cancer of this type are as follows:
1. Breast Cancer: Women with mutations of BRCA1 and 2 are at more risk. Women with a mutation of BRCA1 have an 80-90 % lifetime risk.
2. Ovarian Cancer: This type of cancer is closely associated with breast cancer.
Both these tumors are seen in many dominant families, and very commonly, the same person can be affected.
3. Colorectal carcinomas.
Initially, the doctor will ask about the symptoms being faced by you and your family and personal history. Following this, a physical examination and various required tests are done. Familial cancers should be suspected if there is a family history, development of adult-type carcinomas at an early stage, numerous independent carcinomas.
For specific cancers, there are specific examination tools and types as follows:
Breast cancer: Mammography, self-examination of breasts, regular examination by a physician.
Familial melanomas: Regular monthly skin examinations, dermatologic evaluation twice a year, and early excision of any suspicious lesion in the body.
Apart from these, genetic testing is necessary. This is more indicated in those who are known to have a risk of developing cancer due to gene issues or family history. This testing helps in identifying the disease progression or transmission pattern in the families, and required steps for early management can be done. ·
The symptoms typically depend on the cancer type and the involved site, along with the individual variation.
The best way to prevent or early diagnosis is family history, self-examinations, and genetic testing. The treatment depends on the type of tumor, site involved, individual factors or variations, the stage of the tumor, etc. This will be decided by the physician and explained to you after the diagnosis.
Hereditary cancer syndrome can present in various types, and early diagnosis and management are possible with genetic testing and various other methods to improve the prognosis. To know more about this syndrome, consult a specialist online using online medical platforms.
Last reviewed at:
13 Sep 2021 - 4 min read
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