Researchers at Samsung Medical Center have found critical characteristics of Asian women with breast cancer, finding them to be younger and sometimes face a worse prognosis than Westerners.
Breast cancer is known to occur mainly after menopause, according to studies that have shown 85 percent of cases arising in postmenopausal women in America and Europe.
According to Samsung Medical Center (SMC), however, around half of breast cancer cases in Asia occur in premenopausal women under 40 years old, indicating a sizeable epidemiological difference from the West.
|(From left) Professors Nam Seok-jin, Park Yeon-hee, Park Woong-yang
A joint research team set out to identify the characteristics of young Asian breast cancer patients who have not gone through menopause.
The joint research team was led by Professors Nam Seok-jin from SMC’s Department of Breast and Endocrine Surgery and Park Yeon-hee from the Department of Hematology-Oncology, SMC’s Genome Institute Director Park Woong-yang, and Dr. Zhengyan Kan from Pfizer.
The team conducted a prospective genomic analysis of cancer tissues obtained from 187 breast cancer patients at SMC and then compared them to those from The Cancer Genome Atlas (TCGA) to examine the differences.
Analysis showed breast cancer characteristics of Asian patients were significantly different from that of the TCGA.
Findings showed Asian patients were around 20 years younger. The average age of patients in the SMC data was about 40 years old while the average of those in the TCGA data was 58 years old.
Regarding the clinical type of breast cancer, Asian patients were three times more likely to have estrogen-receptor-positive and human epidermal growth factor receptor 2 positive breast cancer (ER+ / HER2+). SMC data showed 16.1 percent of patients with ER+ / HER2+ breast cancer, whereas TCGA data showed 5.4 percent.
At the molecular level, SMC showed 39.2 percent to be in the luminal B category, which was higher than the 33.2 percent from TCGA data. Luminal B cancer generally grows a bit faster than luminal A cancer and have a slightly worse prognosis.
More Western women were also found to be in the luminal A category, known to have low cancer activity and have the best prognosis. TCGA Data showed 43.7 percent of women were luminal A, while SMC data showed 28.3 percent to be in the same category.
Genetic mutations also differed.
Findings indicated that the degree of mutation of the BRCA gene, known to affect the incidence of breast cancer, was higher in Asian patients at 10.8 percent while lower in TCGA patients at 4.7 percent.
Another cancer-related gene, TP53, was also found in 47.9 percent of Asian patients and only in 32 percent of patients studied by the TCGA.
The researchers also noted that Asian patients had more tumor-infiltrating lymphocytes (TIL), an immune cell, and decreased secretion of TGF-β, which inhibits breast cancer cell growth.
"For Asian women, breast cancer is a terrible disease that afflicts life at a relatively early age,” Professor Park said. "This study will serve as a stepping-stone to the development of new therapies in the future with the understanding of Asian young breast cancer patients deepening to the molecular level.”
The study was published in the recent issue of Nature Communications.
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