Consultant Surgical Oncologist & HIPEC Specialist


Most people have at least one loved one affected by cancer.  This can sometimes create an impression that cancer runs in families or is inherited. A small number of cancer cases (approximately 5-8 percent of all cancers) are directly caused by a single genetic change (or mutation) that is passed down from generation to generation leading to significantly higher cancer risk compared to the general population.

It is not uncommon for more than one member of a family to have cancer. Cancer can occur in families:

  • By chance (Most common)
  • Because family members have risk factors in common (such as environmental and lifestyle influences)
  • Because there is an inherited faulty gene causing an increased chance of cancer (uncommon)

More likely, though, cancer occurs by chance and may also be linked to a combination of certain genetic and lifestyle risk factors shared within a family.

Is Cancer Hereditary?

Heredity describes the passing of DNA (genetic information) from parent to child. Although many people have a family member with a history of cancer, the vast majority of cancers are not due to heredity. People who inherit DNA associated with cancer risk will not necessarily get cancer; however, their risk of developing cancer during their lifetime is higher than average. It’s estimated that around 3-8% of 100 cancers are associated with an inherited faulty gene.

What Percentage of Cancers are Caused by Hereditary?

The percentage of cancers caused heredity varies by the specific type of cancer. In general, only about 10% of cancer is hereditary.


It’s only likely that a cancer gene is present in a family if:

  • there are 2 or more close relatives on the same side of the family (your mother’s or your father’s side) with the same type of cancer, or with particular types of cancer that are known to be linked – for example, breast and ovarian cancer or bowel and womb (UTERUS) cancer
  • cancers are occurring at young ages (before the age of 50)
  • a close relative has had 2 different types of cancer (rather than 1 cancer that has spread)

Is Hereditary Cancer Detectable By Genetic Testing?

  • Sporadic and familial cancers are not detectable by DNA testing; this means over 90% of cancers would not be detectable by genetic testing. Furthermore, only certain risk genes for hereditary cancers are detectable.
  • Genetic testing is an option for those who want more information about their cancer risk.
  • Depending on the type of testing being ordered, a sample of blood, saliva or tumor tissue may be obtained for analysis

Why aren’t all hereditary cancers detectable by testing?

This is because current DNA tests detect only a very limited number of potential genetic changes associated with cancer risk. Additionally, thousands of potential genes and thousands of potential genetic changes are associated with hereditary cancer risk.  Only a small handful of these cancer-risk mutations are identified

Is doing  genetic testing would be useful?

  • Genetic testing in an oncology setting is a valuable tool that a healthcare provider can use to better understand a patient’s unique risk for cancer as well refine their cancer treatment
  • If you have a cancer diagnosis, genetic testing will not tell you whether or not your cancer will come back or spread to another site. Instead, it will help you understand why you developed and your risk for a new cancer.
  • Genetic testing will also inform management strategies for unaffected family members as well.

What should I do if I have a family history of cancer?

What is the first step? Consultation with a genetic counselor or Oncologist may be very beneficial if you have a family history of cancer that matches the description of “hereditary cancer” described above. At our Best Oncology Institute in Chennai  , there is a multidisciplinary Oncology  team of  genetic counselors, surgical oncologists , medical oncologists ,Molecular Pathologist  who are all specialize in high-risk patients and also social workers to help patients understand their level of risk based on their family history and what they can do to detect cancer early or prevent it altogether.


Although it may be difficult to hear that there may be a genetic mutation causing the cancer in the family, most individuals ultimately find this information very empowering. Once equipped with this knowledge, individuals and their healthcare team can establish the best plan for prevention and early detection of cancer.  You can work with your healthcare provider to create a personalized screening and prevention plan, designed to help reduce your risk of developing cancer. This might include:

Earlier and more frequent screenings:

For example, if you have an increased risk for breast cancer, your healthcare provider might recommend mammograms at an earlier age colonoscopy every year if there is a high risk of colon cancer , Removing a polyp found at the time of a colonoscopy will reduce the risk of developing a colon cancer.

Preventive measures:

Your healthcare provider may suggest preventive measures, such as certain medications that can reduce your cancer risk.

Proactive care for your family:

As hereditary health disorders run in families, your results can help your loved ones understand their hereditary cancer risk.

Dr Vimalathithan , best Oncologist in Chennai says about the cancer risk in family that :

People who inherit DNA associated with cancer risk will not necessarily get cancer; however, their risk of developing cancer during their lifetime is higher than average, meaning that  INHERITED GENES DO NOT NECESSARILY MEAN A PERSON WILL GET CANCER.” .

Determining if your family has an inherited genetic mutation may not only prevent you from developing cancer, but also your loved ones