I smoke and I've researched this issue into the ground. Its pretty accurate.
No you haven't! This is a classic case of data dredging and selective presentation of data. For starters, amongst smokers with small primary lung cancers, smoking cessation is associated with an almost 3-fold reduction in cancer recurrence.
(annals of internal medicine http://www.annals.org/cgi/content/abstract/119/5/383)
Not only that, but sustained quitters (14.5 years in this study
Also, smoking cessation dramatically reduces heart disease and stroke mortality. The number one killer of smokers (surprise, surprise!) is not cancer but in fact heart disease. Heart disease is also the leading cause of death in the US with 1 in 3 people dying of heart trouble. Hence, even if the benefits in terms of cancer reduction are modest, smoking cessation considerably reduces the number of people dying.
Get your facts right!