Not shown in Table 6 are the dose-response results from the Fifteen County Study [ 14 ], which did report a significant trend (p = 0.04) with ounces/week ST ever used (though not with years used), based on seven ST-exposed cases.
IARC Monograph 89 [ 2 ] did not include some recent studies [ 11 , 15 ] and based its conclusions on four studies; one of these [ 9 ] did not report a significant relationship with ST use, one of these [ 13 ] reported a marginally significant association with chewing tobacco but not snuff, one of these [ 14 ] reported no overall association with ST use, but a marginally significant trend with amount used in an analysis that, as explained above, is biased, and one of these [ 10 ] reported an association with snuff use in an analysis which effectively assumed that such use would not change over a follow-up period of over 30 years, and also found no association with snuff use in never smokers.
There is, however, more indication of an effect in cohort studies, in studies in Sweden or Norway, and in studies of snuff, where fixed-effect estimates of the RR associated with ST exposure are all significant or borderline significant (cohort 1.75 95% CI 1.20–2.54, Sweden or Norway 1.78, 1.11–2.85, and snuff 1.54, 1.00–2.37).