Modifying influences of betel quid ingredients on B(a)P‐induced carcinogenesis in the buccal pouch of hamster

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Abstract
The present study evaluates the incidence of tumors in hamster buccal pouches following short‐term (10 days) and long‐term (6 months) topical exposures to graded doses of benzo(a)pyrene, B(a)P (25 μg, 50 μg and 100 μg per pouch either daily for 10 days or thrice weekly for 6 months) alone or in combination with extract of tobacco (1 mg/pouch, twice daily), betel nut (1 mg/pouch, twice daily) or betel leaf (5 mg/pouch, twice daily). Given alone, the three doses of B(a)P respectively yielded, 6 months after the last treatment, 4%, 8.7% and 16.7% tumors in the short‐term study, and 20%, 35% and 61% tumors in the long‐term study. Short‐term treatments with individual ingredients of betel quid did not produce any tumors while long‐term treatments produced tumors only with tobacco (17.6%) and betel nut (10.5%). When B(a)P and betel quid ingredients were painted concomitantly for 10 days, there was, depending upon the dose of B(a)P, complete or partial suppression of tumor production. But when B(a)P‐plus‐tobacco or B(a)P‐plus‐betel nut treatments were given for 6 months, there was a considerable increase in tumor incidence. Betel leaf extract, in both short‐term and long‐term studies, expressed its inhibitory influence on B(a)P‐induced tumorigensis.