Quantitative and qualitative mutational impact of ionizing radiation on normal cells.

The comprehensive genomic impact of ionizing radiation (IR), a carcinogen, on healthy somatic cells remains unclear. Using large-scale whole-genome sequencing (WGS) of clones expanded from irradiated murine and human single cells, we revealed that IR induces a characteristic spectrum of short insertions or deletions (indels) and structural variations (SVs), including balanced inversions, translocations, composite SVs (deletion-insertion, deletion-inversion, and deletion-translocation composites), and complex genomic rearrangements (CGRs), including chromoplexy, chromothripsis, and SV by breakage-fusion-bridge cycles. Our findings suggest that 1 Gy IR exposure causes an average of 2.33 mutational events per Gb genome, comprising 2.15 indels, 0.17 SVs, and 0.01 CGRs, despite a high level of inter-cellular stochasticity. The mutational burden was dependent on total irradiation dose, regardless of dose rate or cell type. The findings were further validated in IR-induced secondary cancers and single cells without clonalization. Overall, our study highlights a comprehensive and clear picture of IR effects on normal mammalian genomes.

Psychiatric comorbidities and quality of life in breast cancer patients undergoing radiation treatment: Risk and protective factors.

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.

Age-related risk factors associated with primary contralateral breast cancer among younger women versus older women.

PURPOSE: Contralateral prophylactic mastectomy is increasing, despite unclear evidence of improving survival. To investigate the age-related risk factors for contralateral breast cancer (CBC). METHODS: This study included 8716 patients diagnosed with non-metastatic unilateral invasive breast cancer between 1989 and 2008. Data on primary tumor size, node metastasis, grade and subtype using individual matching were used to adjust for differences in the primary tumor and treatment between younger and older age groups. CBC risk factors, CBC-free survival, and annual CBC risk were analyzed by age. RESULTS: The younger group included 652 patients aged under 35 years, and the older group included 2608 women aged 35 years or older. The median time to CBC development was 6.1 years. CBC was detected in 6.6% of the women in the younger group and 2.5% of those in the older group. Multivariable analysis revealed a relative CBC risk of 2.48 in younger women compared to older women. The risk was significantly higher among women with human epidermal growth factor receptor 2 (HER2)-overexpressing tumors (hazard ratio [HR] 4.98), a family history of breast cancer (HR 7.79), and anti-hormone therapy (HR 3.46). In younger women with HER2-positive cancer, CBC occurrence peaked at 4.6 years after surgery, in those with hormone receptor-positive cancer, it peaked at 7.1 years after surgery, and in triple-negative disease cases, and it increased steadily over time. CONCLUSIONS: After adjusting for primary breast tumor characteristics, patients < 35 years old had 2.5 times the risk of CBC development compared to the older women. CBC occurrence peaked within 5 years after primary breast cancer in younger women with the HER2-positive subtype and after 5 years in cases with the hormone receptor-positive subtype.

Young age is associated with ipsilateral breast tumor recurrence after breast conserving surgery and radiation therapy in patients with HER2-positive/ER-negative subtype.

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.