Epidemiology of Second Non-breast Primary Cancers among Survivors of Breast Cancer: A Korean Population-based Study by the SMARTSHIP group

Cancer Res Treat. 2022 Dec 27. doi: 10.4143/crt.2022.410. Online ahead of print.

ABSTRACT

PURPOSE: To evaluate the incidence and prognosis of second non-breast primary cancer (SNBPC) among Korean survivors of breast cancer.

MATERIALS AND METHODS: Data from the Korean National Health Insurance Service were searched to identify women who received curative surgery for initial breast cancer (IBC) between 2003 and 2008 (n=64,340). Among them, patients with the following characteristics were excluded: other cancer diagnosis before IBC (n=10,866), radiotherapy before IBC (n=349), absence of data on sex or age (n=371), or male (n=248). Accordingly, data of 52,506 women until December, 2017 were analyzed. SNBPC was defined as a newly diagnosed SNBPC that occurred five years or more after IBC diagnosis.

RESULTS: The median follow-up time of all patients was 12.13 years. SNBPC was developed in 3,084 (5.87%) women after a median 7.61 years following IBC diagnosis. The 10-year incidence of SNBPC was 5.78% (95% CI, 5.56-6.00). Higher SNBPC incidence was found in survivors with the following factors: old age at IBC diagnosis, low household income, and receiving combined chemotherapy with endocrine therapy, whereas receiving radiotherapy was related to a lower incidence of SNBPC (hazard ratio = 0.89, p<0.01). Among the patients with SNBPC, the 5-year survival rate was 62.28% (95% CI, 65.53-69.02).

CONCLUSION: Approximately 5% of breast cancer survivors developed SNBPC within 10 years after IBC diagnosis. The risk of SNBPC was associated with patient’s age at IBC diagnosis, income level, and a receipt of systemic treatments.

PMID:36596730 | DOI:10.4143/crt.2022.410

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