Re: verrucous leukoplakia

[tirath]

A smokeless tobacco etiology for oral cancer was first suggested by James Ewing, who noted that cancer in the mouths of tobacco chewers most often developed at the site of quid placement. Ewing’s premise was reiterated in Western clinicopathologic reports published during the 1940s, with specific reference to verrucous carcinoma. The high relative frequency of oral cancer (all types) in India, moreover, had focused attention on the causative role of chewing tobacco as early as 1908, when it was determined that an amazing 71-92% of all carcinomas diagnosed in hospital outpatients arose from the oral mucosa.

Verrucous carcinoma, a low-grade variant of squamous cell carcinoma, is so closely aligned with the use of snuff and chewing tobacco that it has been called the “snuff dipper’s cancer,” even though it is not the most common form of carcinoma resulting from this habit, and even though it has been reported from numerous anatomic sites other than the oral mucosa (larynx, ear canal, vagina, penis, bladder, rectum, soles of feet, dentigerous cyst). It is, furthermore, now known that 16-51% of oral verrucous carcinomas are found in persons without tobacco habit. Obviously, other etiologic agents may be involved, with immunosuppression, human papillomavirus and other viruses being most recently implicated. Nevertheless, it cannot be denied that the most common site of occurrence for this cancer remains the oral mucosa and the majority of oral cases are found in persons who habitually chew tobacco or snuff.

The typical clinical presentation of oral verrucous carcinoma has long been known, as has its remarkably innocuous appearance and biological behavior when not associated with the devastating premalignancy, proliferative verrucous leukoplakia. Relative frequency rates for biopsy service cases are also known: this cancer represents 1-10% of all oral squamous cell carcinomas diagnosed by U.S. hospitals and dental schools.10 In India, approximately 7% of oral cancers are verrucous carcinomas.

The age-adjusted average annual incidence rate for oral verrucous carcinoma is 0.1-0.3/100,000 person-years (0.2-0.3 for males, 0.0-0.3 for females). Among males over 64 years of age the incidence rate for verrucous carcinoma increases to 3.2/100,000 person-years. Verrucous carcinoma is among the least common of the oral carcinomas, representing only 3% of the total.

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