Is a Difference in the Incidence of Cancer Plausible in Less than 2 Years of Follow-up?
One of the criticisms levelled against these studies is that they involved short follow-up periods and, where differences in cancer incidence emerged, these were seen in time intervals of less than 2 years, a fact that seemed implausible to some commentators. However, it is our opinion that it is indeed biologically possible for differences in the cancer diagnosis rate to arise in this timespan, as the observed effects are likely to reflect not the initiation of new tumours but the growth of subclinical tumours into diagnosable volumes. It is considered likely that such subclinical lesions are common in most adults – autopsy studies suggest that undetected cancers are present in a sizeable proportion of adult men[46] and women.[47] Evidence of the plausibility of rapid changes in risk of clinical cancer diagnosis is provided by the rise in breast cancer incidence in the months that follow pregnancy[59] and, conversely, by the reduction in breast cancer incidence that was observed in the immediate aftermath of the fall from grace of oestrogen replacement therapy,[60] as well as by the reduced risk of cancer that is observable in the early months following bariatric surgery.[61,62]
Int J Clin Pract. 2010;65(5):628-636. © 2010 Blackwell Publishing
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