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Young breast cancer patients are more likely than old patients to experience ipsilateral breast tumor recurrence (IBTR) after breast conserving surgery (BCS). However, the pathological processes underlying this relationship have not been elucidated. We investigated the effect of young age on IBTR in a Korean cohort of women with different molecular subtypes of breast cancer. We analyzed data of 2,102 consecutive breast cancer patients who underwent BCS and post-surgical radiation therapy (RT) at two Korean institutions between 2000 and 2005. Patients were classified as young (≤ 40 years; N = 513) or old (> 40 years; N = 1,589). Breast cancer subtype was determined by estrogen receptor (ER), progesterone receptor (PR), and HER2. Median follow-up duration was 61 months. The 5-year IBTR rate was 3.4% in young patients and 1.1% in old patients (P < 0.001). Univariate analysis indicated that IBTR rate in young patients with luminal A and HER2 subtypes was significantly greater than in old patients with these subtypes (P = 0.015 and P < 0.001, respectively). Multivariate analysis, which used luminal A subtype in old patients as reference, indicated that HER2 subtype in young patients was associated with increased risk of IBTR (hazard ratio, HR = 12.24; 95% CI: 2.54-57.96). Among old patients, HER2 subtype was not associated with increased IBTR. In conclusion, young women had a higher rate of IBTR after BCS and RT than old women. This difference is mainly among women with HER2 subtype. Aggressive local control and adjuvant therapy should be considered for young women with HER2 subtype breast cancer.

Whole-genome sequencing (WGS) of human tumors and normal cells exposed to various carcinogens has revealed distinct mutational patterns that provide deep insights into the DNA damage and repair processes. Although ionizing radiation (IR) is conventionally known as a strong carcinogen, its genome-wide mutational impacts have not been comprehensively investigated at the single-nucleotide level. Here, we explored the mutational landscape of normal single-cells after exposure to the various levels of IR. On average, 1 Gy of IR exposure generated ∼16 mutational events with a spectrum consisting of predominantly small nucleotide deletions and a few characteristic structural variations. In ∼30% of the post-irradiated cells, complex genomic rearrangements, such as chromoplexy, chromothripsis, and breakage-fusion-bridge cycles, were resulted, indicating the stochastic and chaotic nature of DNA repair in the presence of the massive number of concurrent DNA double-strand breaks. These mutational signatures were confirmed in the genomes of 22 IR-induced secondary malignancies. With high-resolution genomic snapshots of irradiated cells, our findings provide deep insights into how IR-induced DNA damage and subsequent repair processes operate in mammalian cells.

Objective The primary goal was to evaluate the prevalence of psychiatric comorbidities and changes in psychological distress levels among breast cancer patients receiving radiotherapy (RT). The secondary goal was to determine risk and protective factors for psychiatric comorbidities of these patients. Methods From June 2018 to November 2019, patients were recruited from the hospital, Department of Psychiatry. Patients completed baseline surveys after seeing their radiation oncologist and prior to the first treatment, which was scheduled to take place within 7 days (visit 1, baseline); visit 2 occurred within 7 days after RT completion, and visit 3 occurred at 6 weeks after RT completion. A total of 99 patients participated in the study at visit 1; 56 patients completed the study through visit 3. Results Although changes in psychiatric comorbidities and overall quality of life were observed in patients with breast cancer prior to, during, and after RT, the differences were not significant among visits. Patients diagnosed with psychiatric comorbidities after RT had exhibited risk factors at previous visits, including preexisting psychiatric comorbidities, functional deterioration, and more severe symptoms related to breast cancer. Based on the results, the psychological characteristics of optimism and resilience can be considered as protective factors for psychiatric comorbidities. Conclusions The results suggest that early detection and follow-up of psychological distress and poor quality of life at the onset of RT are of paramount importance, and that psychosocial interventions to enhance protective factors (optimism and resilience) may be helpful.

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