Physicians should use both Western-centric and the Chinese-centric databases when assessing patients with a relevant ethnic background, the authors argued. The cost and complexity of this approach is worth the effort to catch more mutation carriers, they added. These patients could then be offered solutions like elective mastectomy to reduce their chances of early death. They also warned about the potential possibility of investigators missing out on other types of cancer-risk mutations that vary in nonwhite populations, if researchers do not carry out similar studies of mutation variants in other diseases.

The results also showed some concerning findings. Chinese women didn’t need to be overweight to develop breast cancer; 83% of the patients had a body mass index (BMI) under 22.9 (a still-thin 23 is the BMI at which diabetes risk increases in Asians, from an epidemiological standpoint). Family history also didn’t seem to matter; more than 70% had no family history of breast cancer, meaning that the parameters for early diagnosis in the West, such as a mammogram at 40 for a positive family history, may not be enough in Chinese populations. The women were not getting diagnosed early enough; the majority were diagnosed at a more advanced stage than stage I.

While the “traditional” image of breast cancer in the West is a picture of a Caucasian woman of European or North American descent in her 60s, this study should remind physicians and scientists about the complexity underlying calculations of disease risk and incidence of the most common cancer among Chinese women.

On the study, Stephen J. Chanock, MD, director of the National Cancer Institute’s (NCI)’s division of cancer epidemiology and genetics, said: “The findings of Bhaskaran et al. underscore the importance of data sharing on a global scale so that we may more fully understand the risk conferred by variants in BRCA1 and BRCA2 across diverse populations.”

Reference

  1. Bhaskaran SP, Chandratre K, Gupta H, et al. Germline variation in BRCA1/2 is highly ethnic-specific: Evidence from over 30,000 Chinese hereditary breast and ovarian cancer patients [published online January 31, 2019]. Int J Cancer. doi: 10.1002/ijc.32176