Ethnicity in breast cancer affects survival

[kkmalaysia]

There are significant differences in the stage of presentation of breast cancer among the ethnic groups in Malaysia, says a local surgeon.

Data gathered by University Malaya Medical Centre (UMMC) in 2008 showed that 41.7 percent of Malays, 18.9 percent of Chinese and 22.8 percent of Indians presented with late-stage (stage 3 and 4) breast cancer, said Professor Yip Cheng Har, of UMMC’s department of surgery. The higher rate of late-stage presentation among Malays, she added, may be due to socioeconomic factors.

She told Medical Tribune that it is precisely because of these differences in stage presentation that breast cancer survival rates vary widely. “Since Malay women [present] at later stages compared with Indians and Chinese, it is not surprising that Malay women have a poorer survival [rate].”

The National Cancer Registry (NCR), launched in June 2003, has produced three reports, the latest being the NCR 2003-2005, which noted a total of 11,952 cases of breast cancer during that period.

On the age standardized rate (ASR), she said that while the overall ASR was 46.4 per 100,000, it varied significantly among the three races, with 59.8 per 100,000 in Chinese, 54.1 in Indians and 34.9 in Malays. “This translates into 1 in 16 Chinese and 1 in 28 Malay women developing breast cancer in their lifetime.”

The difference in the incidence rate between the Malays and Chinese, said Yip, could be explained by the risk factors associated with breast cancer. “Chinese are more likely to have fewer children, have their first child later, and also more likely to breastfeed for shorter periods than Malay women,” she said, adding that all these are known to be risk factors for developing breast cancer.

She believes that other possible risk factors for the Chinese could be related to their [generally] higher socioeconomic status, diet and genetics. “There is also a possibility of under-reporting among Malay women as they are more likely to seek alternative therapy and, hence, not present to the medical practitioner.”

Yip said that one of the most striking differences between breast cancer in Asia and the West is the age at presentation. “More than 50 percent of women with breast cancer in Asia are in the premenopausal group, unlike in western countries where 75 percent of women with breast cancer are postmenopausal.”

The NCR report also found that 48.1 percent of women with breast cancer were below the age of 50. The mean age was 48.1, 51.4 and 52.3 years for Malays, Chinese and Indians, respectively.

It is difficult, said Yip, to explain the younger age in Malay women. She postulated that it could be because the majority of older Malay women live in rural areas and may opt for alternative medicine; hence, these cases often go unreported. Another reason could be the difference in the population pyramid between the races: Malays being the ethnic majority in the country; Malay women have a higher fertility rate; and, there are more Malay women in the younger age bracket compared with other ethnic groups.

She said that in countries where rates are low, especially in Asia, the annual rate of increase is much higher than in high-incidence countries. “There is a geographical difference in the incidence of breast cancer, as well as differences in the stage(s) at presentation and survival,” concluded Yip.

by: Chuah Su Ping
Source: mims.com