The most common type of cancer among women is breast cancer, and among all age groups, the incidence of the disease is highest among women in their 40s, a study showed Wednesday.

According to the study conducted by the Korea Breast Cancer Society, breast cancer accounted for 24.6 percent of cancers in women, explaining that it has been the most common cancer for women since 2016. Only 0.4 percent of males were diagnosed with breast cancer in the same year.

The highest breast cancer rates were among patients in their 40s and 50s, accounting for 33.1 and 29.6 percent of each age group. The organization said it analyzed the different diagnoses and treatment patterns of breast cancer patients registered in Korea’s Central Cancer Registry in 2019.

Among the types of breast cancers, 83.5 percent of women were battling invasive breast cancer -- breast cancer that spreads into the surrounding breast tissue, while the other 16.5 percent were diagnosed with carcinoma in situ -- precancerous cells in a limited area that may not become malignant.

The research pointed out that the rise in the incidence of breast cancer could be related to changes in the socio-cultural environment and a person’s lifestyle, such as starting menstruation increasingly earlier (Korea’s current average age for starting menstruation is 12.9), the country’s waning fertility rate, reduced breastfeeding rates and an increase in the average age for menopause, which in Korea is 49.4.

Although the breast cancer rate is increasing, the study found that a growing number of patients are spotting cancer at an early stage where treatment is more likely to be effective and successful. A full 61.6 percent of the total number of breast cancer patients were treated in stage 0 -- when the abnormal cells haven’t spread to nearby tissue -- or stage 1 -- when the cancer has not grown deeply into nearby tissues.

The study also noted that active preventative breast cancer screening has demonstrated efficacy in catching the disease before it develops. Through that process, many patients learn about the signs and symptoms of the disease at an early stage.

Kim Hee-jeong, a professor in Asan Medical Center’s breast surgery division, said getting a mammogram is recommended every two years for women over 40, and the country recorded a 59.7 percent screening rate for women in 2015.

Also, the survival rates for breast cancer are steadily increasing, according to the study.

The five-year survival rate, which indicates the percentage of people alive five years after being diagnosed or starting treatment for a disease, stood at 93.6 percent between 2015 and 2019, up 14.3 percent compared to the figure between 1993 and 1995.