A new study, presented today at the American Association for Cancer Research Third Annual International Conference on Frontiers in Cancer Prevention Research, now suggests that the increased incidence may be linked to increased domestic production of a popular legal stimulant in Asia called betel quid.
"Recent findings have spurred a great debate about whether the government should curb the expansion of domestic betel quid cultivation," said Dr. Chiun Hsu, from the Department of Oncology, National Taiwan University Hospital. "It is our hope that these findings will prove helpful in shaping future public health policy on this issue."
Chewing betel quid, traditionally practiced in many parts of Asia and in Asian-immigrants around the world, can be likened to tobacco use in the states. It is often rolled like a cigar or intricately folded and generally consists of a betel palm leaf spread with lime paste (calcium hydroxide) wrapped around a slice of areca nut. Betel quid is chewed for many reasons, including for its stimulant effects, to satisfy hunger, to sweeten the breath, and as a social or cultural practice.
However, betel quid also is considered a nuisance in Asia where the reddish juice, generated by the act of chewing betel quid, can be found all over the ground and on public buildings. Also considered a major public health risk, it is believed to be a leading cause of mouth cancer in this part of the world.
In this study, researchers used the age-period-cohort (APC) model to examine the incidence trends for men and women in Taiwan of nasopharyngeal carcinoma versus head and neck cancer. The APC model was designed to estimate the relative effects of patient age, calendar year at diagnosis and patient birth cohort on the incidence trend of a specific disease. Age-specific incidences of nasopharyngeal carcinoma and head and neck cancer were plotted by calendar year at diagnosis and by birth cohort.
Data revealed that for head and neck cancers, the relative risk for men who were born in the 1972-1980 cohort is 45.67 compared with men born in 1932-1940, indicating a strong cohort effect. By contrast, the relative risk is 0.69 for nasopharyngeal carcinoma. A trend of positive period effect was recorded for head and neck cancer, whereas the period effect for nasopharyngeal carcinoma was not significant. The birth cohort effect indicates factors that may have different exposure levels in different birth cohorts and require prolonged time to manifest their effects on the body. Period effects, on the other hand, usually reflect factors that affect all age groups equally at a given period of time, such as introduction of new diagnostic or therapeutic techniques. The strong cohort effect for head and neck cancer was associated with a 6.85 fold increase in the domestic production of betel quid for the same time period, suggesting a strong correlation between betel quid usage and the incidence of head and neck cancer.
According to the World Health Organization, oral cancers are more common in parts of the world where betel quid is chewed. Of the 390,000 oral and oro-pharyngeal cancers estimated to occur annually in the world, 228,000 (58%) occur in South and South-East Asia. In some parts of India, oral cancer is the most common cancer. Striking evidence has emerged from Taiwan and China, where the incidence of oral cancer in men has tripled since the early 1980s, coinciding with a steep rise since the early 1970s and predominantly among men, in the practice of chewing betel quid.
Founded in 1907, the American Association for Cancer Research is a professional society of more than 24,000 laboratory, translational, and clinical scientists engaged in all areas of cancer research in the United States and in more than 60 other countries. AACR's mission is to accelerate the prevention and cure of cancer through research, education, communication, and advocacy. Its principal activities include the publication of five major peer-reviewed scientific journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention. AACR's Annual Meetings attract more than 15,000 participants who share new and significant discoveries in the cancer field. Specialty meetings, held throughout the year, focus on the latest developments in all areas of cancer research.