Were you cognisant that in Malaysia, the lifetime risk of women developing breast cancer is the highest among Chinese?
“Breast cancer incidences vary between and within Asian countries,” Prestige Malaysia 40 under 40 alumna Dr Ho Weang Kee says. The grim prospect will inevitably descend on one in every 22 Chinese, 23 Indian and 30 Malay women at some point in their lives. However, there exist intricate nuances once you dive into the subject.
Though Malaysia is spearheading research into breast cancer, especially among Asian women, thanks to dedicated academics like Ho and Prof Datin Paduka Dr Teo Soo-Hwang who leads a phalanx of young and exuberant scientists at Cancer Research Malaysia, for a long time, we couldn’t be absolutely certain that the polygenic risk score used for the prediction of breast cancer among European women could apply to Asians. One reason being the insufficiency of valuable data that could help shed more light.
“Historically, breast cancer incidences in Asian women have been lower compared to those of European women. Hence, it is not surprising that priority has been given to the higher incidence group,” Ho says, revealing studies in Asia were hitherto nearly six times smaller than studies in Europe.
According to Teo, the lack of Asian representation in cancer research is not so much about being overlooked, as it is about resources. She says due to the majority of funding for cancer research flows within Western countries, and as a result, most research tends to be done on Caucasians. “Cancer Research Malaysia is working hard to change these statistics,” asserts the chief executive of Cancer Research Malaysia, “and we are leading the Asian research for two global breast cancer studies, but we can’t do it alone.”
As dire projections such as Asian women facing up to 50% increase in breast cancer incidences between 2012 and 2025 set in, Ho was nudged into taking matters into her own hands. Teaming up with Teo, and collaborating with Prof Douglas Easton and Prof Antonis Antoniou from University of Cambridge, as well as partners from across the region, the University of Nottingham Malaysia associate professor led the groundbreaking collaborative study.
45,223 Asian women, of whom 34,957 were recruited into 13 case-control studies, and 10,266 women (of which there were 413 breast cancer cases) were recruited into a prospective study. Ho says the purpose was to determine if the genetic tool developed to help European women predict their breast cancer risk would also work in Asian women. This is the first time this genetic tool has been used to predict breast cancer risk in Asian women on such a massive scale.
The polygenic risk score is a genetic test focusing only on some genetic markers distributed in different parts of the genome, according to Ho. She explains that in the case of the European breast cancer polygenic risk score, there are 313 genetic markers included in the score.
“This means that through testing 313 markers of three billion markers in a person’s unique genome, it enables us to generate a risk score that can tell a woman how likely she is going to get the disease.”
This study holds significance particularly in the local context where Malaysia ranks considerably lower than developed Asian countries in the five-year survival rate. “The percentage of people who stay alive five years after breast cancer diagnosis is around 80-90% in well-off countries in Asia,” Ho says, before continuing, “but in Malaysia, it has been reported that the five-year survival rate is only 49%, meaning that nearly half of the women diagnosed with breast cancer die of the disease.”
Ho explains one of the causes that contribute to the poor survival rate is many are diagnosed at a late stage, giving patients little room to manoeuvre. If detected early, the chances of surviving breast cancer can be as optimistic as over 90%. Having an effective strategy will ensure that women can avoid and reverse this predicament. Studies into the prediction of breast cancer will no doubt help ameliorate the overall efficacy.
Both Ho and Teo are of the opinion that age-based screening doesn’t acknowledge the genetic differences exist between individuals. By ignoring their distinct characteristics, some end up diagnosed at advanced stages, while others are simply over-diagnosed. To tailor to individuals, scientists are increasingly looking at developing more accurate ways to provide women with their personalised risk of breast cancer.
“Using the polygenic risk score, we show that Asian women in the highest risk category have approximately 16% lifetime risk of developing breast cancer; this means one in six women in this risk group will develop breast cancer in their lifetime,” they explain the findings of the study.
“These women would therefore need enhanced breast cancer surveillance to enable early detection of the disease, for instance, attending mammography screening frequently at a younger age.
“Our research shows for the first time that polygenic risk score can accurately provide women with an accurate estimate of their breast cancer risk, and we hope that if this test is provided for all women, we can enable women to choose the screening and prevention that is right for them.
“Equally, being able to provide women their risk of the disease is important and might raise awareness on the disease and encourage them to be vigilant of the changes in their breasts in between screening.”