By: Dr Dodul Mondal, Associate Director, Radiation Oncology, Max Institute of Cancer Care, Max Super Speciality Hospital
Cancer is considered as a modern day epidemic. its incidence and prevalence are increasing slowly but steadily over the years across the globe. As per recent GLOBOCAN 2020 data, almost 20 million new cancer cases were diagnosed worldwide, and 10 million people died of this disease. The cancer incidence has been projected to be almost 30 million in next two decades. There have been spectacular developments in many aspects of cancer. These include but essentially not limited to screening, early diagnosis, treatment, complication prevention etc. Still there are many things to achieve and there are some areas where progress has been limited over decades. Familial cancer is one such area.
What is familial cancer syndrome? It’s a genetic problem where a person harbors a specific or multiple genetic alteration which makes him/her predisposed to have one or multiple cancer and the problem runs in the family.
Am I at increased risk of having cancer? A very common question we often encounter. “Doc, my mom had breast cancer, am I at risk?” or, “Doc, will my kids be affected with similar cancer in future?” are some of the questions. Familial cancers are associated with higher risk of transmission in the family.
What are different types of genetic mutations? There are two basic types, germline and somatic mutations. Almost 5-10% of all cancers are supposedly caused by inherited genetic mutations. A gene can be considered as a basic unit of hereditary information of a person. A mutation is alteration or change in that genetic information. When a mutation comes from a defective sperm or egg at the time of conception, such mutations can be incorporated into the DNA of every cell of the offspring and is known as germline mutation. That means, the child is born with such genetic defect from mother’s womb. And only such germline mutations can be transferred to an offspring. So, in essence, this type of mutations can be considered hereditary or familial as they have the risk of running in the family. The other type of mutation can happen after conception and can involve any cells of the body other than the germ cells (sperm or egg) and known as somatic mutation. Such mutations can not pass on from one person to the children.
It has to be remembered that all cancers are genetic (they happen because of some alteration in the gene) but not all cancers are familial (ability to transfer in the family).
So, cancers which are results of germline mutation, can affect same family members who are blood related. Cancers which are result of somatic mutation, cannot affect other family members.
What are the cancers which can run in family? Many cancers can be associated with high risk of running in family. A very common mutation is TP53 gene mutation. Normally this gene prevents occurrence of cancer by suppressing the growth of tumor. There are some other genes which normally repair a damaged DNA and thus prevents cancer. Mutation of such repairing gene can also lead to formation of cancer. Sometimes multiple cancers happen due to mutation of such genes, and they are known as Familial Cancer Syndrome. Few such syndromes are Li-Fraumeni Syndrome, hereditary breast and ovary cancer syndrome, hereditary non-polyposis cancer syndrome etc. The list is longer. One of such syndromes which is mostly discussed is hereditary breast-ovarian cancer syndrome. This is associated with mutation of BRCA1and/or BRCA2 genes. Almost 7-10% of breast cancers are associated with gene mutations. Among such cases, almost 80% are related to BRCA1/BRCA2 mutation. This gene mutation is associated most commonly with breast cancer, ovarian cancer, fallopian tube cancer, colorectal cancer, uterine cancer, male breast cancer and prostate cancer. Similarly, some blood cancers, colorectal cancers, soft tissue sarcomas, kidney cancers, brain tumors, nerve fiber tumors, skin cancers etc. can also be associated with hereditary cancer syndromes.
How can familial/hereditary cancers be suspected? A suspicious mind is the first requirement to suspect and evaluate such situations. Detailed family history along with family tree can be of great use to suspect familial cancers. Most of the people give a positive cancer history among the blood related family members. Once suspected, genetic screening and testing can be advised along with counseling of the affected person and family.
What are typical features of familial cancers? Other than being associated with family history, these cancers have a tendency to occur at a relatively young age. Sometimes they are associated with multiple cancers. Also, they have a tendency to be more aggressive compared to non-familial counterpart.
Should genetic testing be advised for all? Certainly not. Indiscriminate genetic testing will increase confusion and fear. It is indeed a job of an expert who understands the associated confusions and uncertainties. Given the context of our country, its socioeconomic and cultural practice, advising genetic tests may be difficult for many reasons and needs extreme caution to avoid unnecessary complications in life.
Having a mutated gene synonymous of having a cancer? Essentially No. It only means a higher risk of having certain cancers. People having certain genetic mutations need to be cautious and consult an expert. They should also follow a surveillance program to detect any cancer at the earliest possible time.
Is radiation more harmful when used in such patients? Not necessarily. It needs understanding of the current cancer problem, risk and life threat associated with the already diagnosed cancer and the relative risk of radiation causing any additional harm. Sometimes, radiation treatment is a life saving measure and the patient can die out of the already diagnosed cancer if not treated properly, well before the projected timeline when he/she could develop radiation induced second cancer causing any harm. So, avoiding radiation only because someone has a mutation can be dangerous.
What should I do? If you think you can have a higher risk of having cancer for some reason, you should talk to an expert. If you have strong family history of cancer or multiple cancers or cancers at very young age, you should seek help from an expert at the earliest possible time. And, last but not the least, Do not do random genetic testing.