If you're the kind of smoker who likes to have a cigarette first thing in the morning, you may be more likely to develop cancer than smokers who hold off until later in the morning for that first smoke.

According to two new studies, smokers who regularly have their first cigarette within a few minutes of waking may have a higher risk of developing lung and head and neck cancers than other smokers.

Needing a cigarette first thing in the morning is thought to be a reflection of a strong addiction to nicotine. Researchers at Penn State College of Medicine in Hershey Penn., led a team who looked at whether the time of day of the first cigarette affected smokers' risk of lung and head and neck cancers.

They looked at 4,775 patients with lung cancer and 2,835 other smokers without cancer.

Compared with those who waited more than an hour after waking to have that first cigarette, those who smoked within 30 minutes of waking were at a 79 per cent higher risk of developing lung cancer. Those who smoked 31 to 60 minutes after waking were at a 31 per cent higher risk.

The findings were adjusted to take into account how much the smokers had smoked over their lifetimes.

The second study looked at cancers of the head and neck. This analysis included 1,055 patients with head and neck cancer cases and 795 smokers without cancer.

Again, the researchers found that compared with people who smoked more than 60 minutes after waking, those who took a cigarette within 31 to 60 minutes after waking were at a 42 per cent higher risk of developing head and neck cancer, while those who smoked within 30 minutes were at a 59 per cent higher risk of developing head and neck cancer.

Lead author Dr. Joshua Muscat says smokers who need a cigarette first thing in the morning may be more addicted than smokers who refrain for a half hour or more.

"It may be a combination of genetic and personal factors that cause a higher dependence to nicotine," he said in a news release.

These smokers might also have higher levels of nicotine and possibly other tobacco toxins in their body.

The authors say that since it appears that early-morning smokers are at high risk of developing cancer, they would benefit from targeted smoking cessation programs.

Both studies are published online in Cancer, the journal of the American Cancer Society.