Breast, ovarian cancers: DNA test, regular screening reduce mortality in women with gene mutations

SINGAPORE – Women with a family history of cancer should go for DNA testing regardless of age to see if they have mutated hereditary cancer genes, which put them at high risk of getting the disease in the breasts, ovaries, or elsewhere.

Those found to have the mutated genes should go for cancer screening every year, said associate professor of genomic medicine Joanne Ngeow at Nanyang Technological University’s (NTU) Lee Kong Chian School of Medicine.

Men with the mutated genes are also at risk of getting cancer, even in the breasts, she told The Straits Times.

While mammogram has been proven to be an effective method for detecting breast cancer early, it is recommended only once every two years for women aged 50 and above. Cancer is often missed in many younger women with the mutated hereditary cancer genes.

These findings are from a recent study on carriers of mutated cancer genes in Singapore and Malaysia.

It provides an important framework for estimating cancer risks in Asian carriers, allowing a more tailored approach to managing the disease in Singapore.

Breast cancer is the most common cancer among women here. More than 2,000 women are diagnosed with it every year, and more than 400 die from the disease.

The study was conducted by Prof Ngeow and other researchers from institutions such as NTU, National Cancer Centre Singapore (NCCS), Agency for Science, Technology and Research, Cancer Research Malaysia and University of Malaya. The findings were published in The Lancet Regional Health – Western Pacific in February 2024.

All men and women have hereditary cancer genes – breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2) – which produce proteins to help repair damaged DNA. However, only some have mutations in either of the genes.

The study, the largest so far on an Asian population, involved 572 Asian families in Singapore and Malaysia with the mutated genes.

Family members were between 20 and 79 years old and of Chinese, Indian and Malay ethnicity. Women made up 95 per cent of the group.

About 13 per cent (144) of the 1,121 BRCA1 carriers were diagnosed with breast cancer, while 5.8 per cent (65) had ovarian cancer. Breast cancer was detected in almost 12 per cent (152) of the 1,275 BRCA2 carriers and ovarian cancer in 1.5 per cent.

The study has also shown that the estimated risks of breast and ovarian cancers for carriers in Singapore are similar to thatof Asians in the West.

“We have healthy exposures, unhealthy exposures, healthy genes and unhealthy genes. So how do we use this information to better help us decide who’s likely to stay healthy, who’s likely to get the disease?” said Prof Ngeow, who heads the Cancer Genetics Service at NCCS.

According to the 2021 Singapore Cancer Registry Annual Report, breast cancer topped the list of cancer cases among women between 2017 and 2021, making up 30 per cent of the total cases. The disease also accounted for 17.3 per cent of cancer deaths – the highest proportion.

Over the same period, cases of ovarian cancer rose to about twice the number in the previous five-year period, ranking sixth in incidence and death for women.

In 2022, a study published under Singapore’s National Precision Medicine Programme listed the entire genetic make-up of 10,000 Singaporean women.

It also looked at hereditary breast ovarian cancer syndrome, which was what Hollywood megastar Angelina Jolie had.