Not including accidental deaths and suicide, the 10 most common causes of death in the United States are diseases. Heart disease and cancer, the two leading causes of death overall in the United States, account for nearly half of the deaths recorded annually — nearly 1.2 million deaths.

To determine the deadliest diseases in the country, 24/7 Wall St. reviewed mortality data from the Centers for Disease Control and Prevention. The deadliest diseases in the United States range from heart disease, which caused 611,105 deaths in 2013, to liver disease, which directly resulted in 36,427 deaths.

Heart disease is by far the most common cause of death in the United States. In an interview with 24/7 Wall St., Dr. Baxter Allen, Chief Resident in Neurology at Weill Cornell Medicine, New York Presbyterian Hospital, explained why heart disease is such a common killer. While people who develop other diseases can often live with the disease for years, this is less so the case with heart disease. “There’s only one heart, and if it stops working, then you’re dead,” Allen said. Additionally, the United States is currently in the midst of an obesity epidemic and “obesity is a major risk factor for diabetes, liver disease, and heart disease.”

Click here to see America’s 10 deadliest diseases.

Cancer is the second leading cause of death in the United States. Since President Richard Nixon declared war on cancer in 1971, enormous investments have been made in cancer research. The National Cancer Institute alone has spent roughly $4.9 billion on cancer research each year since 2005. Yet, a cure has eluded researchers. According to Allen, age is the greatest risk factor associated with cancer, and “as the population ages, which it is significantly with the baby boomer generation starting to hit their 70s, [cancer cases] are likely to increase dramatically.” According to a report by the American Society of Clinical Oncology, cancer will become the leading cause of death in the United States by 2030.

Many of the most common deadly diseases in the country tend to afflict Americans who share similarly unhealthy behaviors. For example, the connection between smoking and certain types of cancer, heart disease, chronic respiratory illness, and stroke is well established. Alcohol abuse also increases the risk of certain cancers as well as liver disease and cirrhosis. Unhealthy behaviors such as these, Allen said, “are all independent risk factors for decreased life expectancy.”

Even diseases that are commonly understood to be genetically predetermined can have additional behavioral risk factors. Experts believe that roughly one third of Alzheimer’s cases may be preventable through the modification of risk factors such as high blood pressure, physical inactivity, and others.

Many of the deadliest diseases are interconnected, and the occurrence of one can increase the likelihood of another in an individual. For instance, kidney disease, one of the leading causes of death, can be caused by both liver failure and heart disease, themselves among the leading causes of death.

For this reason, the deadliness of certain diseases may be underrepresented by the numbers. According to the CDC’s report, diabetes is the seventh leading cause of death, directly responsible for 75,578 deaths in 2013. According to the American Diabetes Association, it is actually relatively rare for diabetes to be recorded as the direct cause of death on the death certificates of diabetics, suggesting diabetes could be underreported as the cause of death.

“The health industry is trying lots of things to address these killers,” Allen said. While the incidence of cancer, for example, may increase with the aging of the population, constantly improving treatments — the result of ongoing cancer research — may continue to improve death rates in the near future. On the other hand, Allen said, “Without a significant breakthrough, Alzheimer’s disease is going to account for an increasingly large proportion of death as it is estimated to triple in number of affected people by 2050.”

In order to determine the deadliest diseases in the United States, 24/7 Wall St. reviewed the total number of deaths attributable to a given disease in 2013 from the Centers for Disease Control and Prevention’s (CDC) annual National Vital Statistics Report, Deaths: Final Data for 2013. Historical death rates per 100,000 from 1999 are age adjusted and also came from the CDC. The report was published on February 16, 2016 and contains figures for the recent period for which data is available.

These are the 10 deadliest diseases in the United States.