It was inevitable that this question would arouse a heated debate, so now that the initial huff and puff is over (sorry for the pun)...........
I too have seen several family members die terrible deaths from lung cancer and other smoking related diseases, but, on the other hand seen several heavily smoking family members out-live their non-smoking contemporarys.
It's all a gamble! In all honesty, 5 cigarettes per day should make no difference, or at the most minimal difference to your health. That applies if you're Mr. or Ms. Average. How do you know where you stand, both genetically and in terms of your personal threshold of damage?
The fact is that you don't know, don't take the gamble. Playing Russian Roulette is also a gamble. Smoking and Russian Roulette both carry a significant mortality risk.
Quit whilst you're ahead! 5 per day should be easy to beat!
Regards,
Old Smokey