Cancer of the nasopharynx
is a rare neoplasm in most countries. However, it occurs at high frequencies
in China and Southeast Asia. The highest incidence rates in the SEER regions
occur among the Chinese. Rates are also high in Vietnamese and Filipino men,
two groups that include persons of Chinese heritage. Incidence rates of nasopharyngeal
cancer are also available for black, Hispanic and white men and for white women
in the SEER areas. There were too few nasopharyngeal cancers diagnosed between
1988 and 1992 in the other racial/ethnic groups to provide meaningful incidence
rates.
The average annual age-adjusted
incidence rate of nasopharyngeal cancer in Chinese men, 10.8 per 100,000, is
1.4 times greater than that of Vietnamese men and nearly 2.8 times greater than
that of Filipino men. In fact, the rate among Filipino men, although relatively
high, is the same as that for Chinese women. Rates of one per 100,000 and lower
occur in black men, Hispanic and non-Hispanic white men and non-Hispanic white
women.
The United States mortality
rates for cancer of the nasopharynx reflect patterns similar to those for SEER
incidence rates. Mortality is highest in Chinese, lower in Filipinos and lowest
among blacks, Hispanics and non-Hispanic whites. No mortality rates are currently
available for Vietnamese. Incidence-to-mortality rate ratios vary, with Chinese
and Filipinos having higher incidence relative to mortality (2.3 for men in
both groups and 3.2 for Chinese women) than other groups (ranging from about
1.7 for white Hispanic men to two for non-Hispanic white men). Incidence and
mortality rates for nasopharyngeal cancer increase through the oldest age group,
although the small number of cases precluded the calculation of reliable rates
for many populations.
The major modifiable risk
factor identified for cancer of the nasopharynx is the consumption of Cantonese
salted fish, which is a common food item eaten from early infancy onward by
groups with high risk of this disease. Other possible risk factors include extensive
exposures to dusts and smoke and regular consumption of other fermented foods.
The role of Epstein-Barr virus in the development of nasopharyngeal cancer continues
to be explored.
Source: Miller BA,
Kolonel LN, Bernstein L, Young, Jr. JL, Swanson GM, West D, Key CR, Liff JM,
Glover CS, Alexander GA, et al. (eds). Racial/Ethnic Patterns of Cancer in the
United States 1988-1992, National Cancer Institute. NIH Pub. No. 96-4104. Bethesda,
MD, 1996.
Graphs showing incidence
and mortality for specific racial and ethnic groups including information
that may not be discussed in the text above, is available at the NCI's
Surveillance, Epidemiology, and End Results (SEER) Web site at: http://seer.cancer.gov/.
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