Yes, this may reduce your risk of cancer, but the health gains depend on other considerations.
How much the risk is reduced will depend on whether a smoker compensates for the reduction in nicotine intake by changing the way they smoke, such as by inhaling more deeply or taking more puffs. Using nicotine replacement therapy (NRT), or other tobacco-dependence medication, alongside trying to reduce cigarette smoking might help to avoid compensatory smoking and is more likely to help to stop smoking completely. It is best to set a goal of stopping smoking completely within a certain period of time, as quitting smoking provides the greatest health benefits. Stopping smoking at any age significantly lowers the risk of dying from all major smoking-related diseases, including cancer, compared with current smokers.
The risk of cancer is determined not only by the amount of time a person has smoked (i.e. years) but also by the intensity of smoking (i.e. the number of cigarettes smoked per day). The influence of duration of smoking in determining cancer risk is believed to be greater than the impact of reducing the number of cigarettes smoked per day. Quitting smoking is best for reducing cancer risk.