According to the Center for Disease Control (CDC) a United States Government Agency here is the breakdown:
Second leading cause of death for 10 - 14 years olds: Malignant Neoplasms (aka Cancer)
Second leading cause of death for 15 - 24 years olds: Homocide
suicide
In the US the leading cause of death in people over 65 is heart disease with cancer a close second.
Heart disease is the leading cause of death among men and women
Breast cancer is the second leading cause of death in women
the second leading cause of death in the US is cancer.
Cancer. Click on "Leading causes of death in America" under Related links below.
smoking
The leading cause of death in Canada in heart disease. The second biggest cause of death in Canada is a stroke.
Homicide, far behind the leading cause of teen death, accidents.
Electrocution
electrocution
heart failure
heart failure