Early contralateral breast cancer development, certain subtypes linked to survival

Key takeaways:

• Women with and without contralateral breast cancer had no significant difference in survival.
• Contralateral breast cancer development within 1.5 years after primary surgery was linked to higher mortality risk.

Early contralateral breast cancer development after primary breast cancer for women with certain subgroups of breast cancer was associated with survival in Korean women, researchers reported.

“The prognosis of patients with breast cancer after developing contralateral breast cancer is an important issue, especially for young patients with breast cancer, who have a higher chance of developing contralateral breast cancer. The reason for this is that they have longer life expectancy, and diagnosis of breast cancer at a young age is a risk factor associated with developing contralateral breast cancer,” Hakyoung Kim, MD, from the department of surgery at Dongguk University College of Medicine at Dongguk University Ilsan Hospital in Goyang, South Korea, and colleagues wrote. “Meanwhile, the age distribution of Korean patients with breast cancer is younger compared with populations in Western countries. However, the few Korean or Asian studies dealing with the association of contralateral breast cancer with survival show varying outcomes.”

Kim and colleagues conducted a cohort study, published in JAMA Network Open, with 16,251 Korean women with breast cancer (mean age, 48.6 years) from the Asan Medical Center in South Korea. All participants were diagnosed with primary unilateral, nonmetastatic stage 0 to III breast cancer from 1999 to 2013. Median follow-up was 107 months through 2018.

The primary outcomes were survival rates of women with and without contralateral breast cancer.

Overall, 418 women developed contralateral breast cancer. Researchers observed no significant difference in overall survival between women with and without contralateral breast cancer (HR = 1.166; 95% CI, 0.82-1.657).

Women who developed contralateral breast cancer within 1.5 years after surgery for primary breast cancer had a higher risk for overall death compared with women without contralateral breast cancer (HR = 2.014; 95% CI, 1.044-3.886). In addition, those with a later diagnosis — after 1.5 years following primary breast cancer surgery — had no significant difference in survival compared with women without contralateral breast cancer.

Women with hormone receptor-positive and ERBB2-negative breast cancer and contralateral breast cancer had a higher risk for overall death compared with women without contralateral breast cancer (HR = 1.882; 95% CI, 1.143-3.098).

“Although our study had a large study population, the number of patients or events, such as overall death, was too small to generalize our results, especially in subgroup studies,” the researchers wrote. “In the future, we could conduct a multicenter study with a larger population to avoid these limitations.”