The number of deaths from cancer was 154.3 per 100,000 South Koreans in 2018, up 0.2 percent from the previous year, according to Statistics Korea.
Lung cancer was the fatalist of cancer-caused deaths, followed by liver cancer, colorectal cancer, gastric cancer and pancreatic cancer.
Heart disease was the second-largest cause of death with 62.4 deaths per 100,000 South Koreans last year.
The number of deaths from pneumonia was 45.4 per 100,000 people in 2018, placing third in the list of death cause and going up by one notch from the previous year amid the aging population.
The aging population also raised the number of deaths from Alzheimer's disease, which was 12.0 per 100,000 South Koreans and ranked the ninth in the list. It was up 22.5 percent from the prior year.
The number of deaths from suicide was 26.6 per 100,000 people in 2018, up 9.5 percent from the previous year. It ranked fifth in the list.
Suicide was the number one cause of death among those aged between 10 and 39, and the second-largest cause of death for those in their 40s and 50s.
Meanwhile, the total number of deaths went up 4.7 percent, or 13,286, over the year to 298,820 in 2018. It was the highest since relevant data began to be compiled in 1983, continuing an upward trend for five years in a row.