There are a range of illnesses that can prompt a self-funded employer to make a claim on their stop-loss insurance policy, but a new study by Sun Life Financial Inc. finds that a majority (53 percent) of the $5.3 billion in such claims paid by insurers from 2012 to 2015 came from just 10 ailments.

The study shows the incredible impact of cancer. All types of cancer account for more than a quarter of all stop-loss claims, with breast cancer alone accounting for 13 percent of the total reimbursements.

Claims that exceeded $1 million continue to be rare—only 319 during the four-year period—but they account for nearly a fifth of the total reimbursements.

They have also increased every year, from 60 in 2012 to 107 in 2015. The number of claims exceeding $2 million, however, has not risen steadily, jumping from two to 20 in 2013, but then dropping again in the subsequent two years.

“By highlighting the conditions that create catastrophic claims and providing insights into trends influencing high costs, we can help employers anticipate what they'll see when self-funding and raise awareness about the importance of cost-containment resources and stop-loss insurance,” says Brad Nieland, vice president of Sun Life Financial's stop-loss division.

Here are the top 10 ailments associated with self-funded employer claims:

10. Septicemia

A condition that arises when the body reacts violently to an infection, damaging critical organs in the process and even leading to septic shock, septicemia resulted in $54.7 million in reimbursements between 2012 and 2015, or 2.4 percent of the total.

Sepsis can be life threatening, with 50 percent of all cases starting as an infection in the lungs.

9. Respiratory failure

Pulmonary collapse or respiratory failure was the ninth leading claim, resulting in $55 million in reimbursements from stop-loss insurance policies. Risk factors for the condition include binge-drinking, smoking, and working in an environment that leads to inhalation of chemicals that irritate the lungs, all issues that employers can have a hand in improving.

Top causes of respiratory failure include lung diseases such as chronic obstructive pulmonary disease, pnuemonia, pulmonary embolism, and cystic fibrosis.

8. Cerebrovascular disease

Most commonly manifested through a stroke, cerebrovascular disease prompted $57.4 million in reimbursements between 2012 and 2015, for 2.4 percent of the total. Although strokes are the fifth leading cause of death for Americans, two-thirds of patients are over the age of 65, suggesting the burden of caring for stroke patients falls mostly on Medicare, rather than employers.

Stroke is the leading cause of long-term disability in the United States, with approximately 795,000 people suffering from a stroke each year.

7. Congestive heart failure

The condition afflicts roughly 2 percent of the adult population and 5 percent of those aged 60 to 69, resulting in $57.8 million in reimbursements from catastrophic insurance policies between 2012 and 2015.

Affecting nearly 5 million Americans, heart failure is the only major cardiovascular disorder on the rise.

6. Transplants