Oncogenetics for the Generalist

- 02 August 2019

Excerpt from a presentation on oncogenetics given by Dr Ai Ling Tan. The presentations aim was to give clinicians a perspective of the emerging and ever-growing field of cancer genetics and its implications on daily practice. This area has gained more impetus as genetic status can impact on treatment decisions and patients are better informed and empowered. Women are more proactive in making decisions on prevention and surveillance.

Everyone has BRCA genes, but it is the mutations (changes) in these genes that increase women’s risk of breast and ovarian cancer. The lifetime risk of breast cancer up to the age of 70 with BRCA1 is 57% and ovarian cancer is 40%. The lifetime risk of breast cancer up to the age of 70 with BRCA2 is 40% and ovarian 18%. There is also an increased risk of pancreatic cancers.

Genetic testing is now offered to all women with non-mucinous ovarian cancer who are younger than 70 as this can affect their prognosis as they may be offered different treatment options if they are BRCA positive. It also offers their families the option of genetic testing and with a combination of surveillance, risk-reducing medication and surgery decrease their risk in some cancers.

“To identify a woman as a carrier after the diagnosis of cancer is a failure of cancer prevention” – Dr Marie Claire King (founder of the BRCA gene).

Unfortunately, there is no role for ovarian cancer screening with imaging or Ca125. This has not been proven to be effective in detecting ovarian cancer at an early stage.

Risk-reducing surgery (removal of the tubes and ovaries) significantly decreases the risk of ovarian cancer. In can also decrease the risk of breast cancer. There are various pros and cons in making this decision and it is important that the discussion is with a specialist who is familiar in this area. There are guidelines for surgery and pathological assessment of the specimens which have to be followed as there is a risk that there is an occult cancer. This would have management implications.

Major specialist bodies around the world advocate that, women who are not at high risk for BRCA mutation and have completed their families, have their fallopian tubes removed at the time of any benign gynaecological surgery as this can also prevent a proportion of ovarian cancers.