In a span of four years, three of six siblings in the Wong family were diagnosed with either breast or ovarian cancer. All three carried a hereditary mutation in the genes known as BRCA, which increases the risk for both diseases - although BRCA is named after the first two letters of 'breast' and 'cancer'.
BRCA genes are present in everyone, says Dr Ava Kwong Hoi-wai, chairwoman of the Hong Kong Hereditary Breast Cancer Family Registry. BRCA1 and BRCA2 are known as tumour suppressors because they help repair damaged DNA in cells that have divided improperly. However, when either of those genes mutate, the repair process can go awry.
According to the National Cancer Institute in the United States, the risk for breast cancer in the general population is 12 per cent, but those who are BRCA-positive carry a 60 per cent risk of developing breast cancer in their lifetime. The risk for ovarian cancer goes up from 1.4 per cent to anywhere between 15 and 40 per cent.
Ethnicity and geography may play a role, as BRCA mutations appear more frequently in the Ashkenazi Jewish, Norwegian, Dutch and Icelandic populations. In Chinese populations, the prevalence and impact of BRCA mutation are not well understood.
To begin with, cancer rates in Chinese communities are different from those in the West, says Kwong. Asians have a 6 per cent risk of breast cancer in the general population. Women in Hong Kong have a 0.8 per cent risk of ovarian cancer, says Dr Tam Kar-fai, a specialist in obstetrics and gynaecology at the Hong Kong Sanatorium & Hospital. Kwong says BRCA mutations increase those risks, but it is not known by how much.
Recognising a need to address this knowledge gap, Kwong established the registry in December 2007 to further research BRCA mutations in the Chinese population and provide genetic counselling, testing and support to high-risk patients.