Germline Genetic and Treatment-Related Risk Factors for Diabetes Mellitus in Survivors of Childhood Cancer: A Report From the Childhood Cancer Survivor Study and St Jude Lifetime Cohorts

PURPOSE

To characterize germline genetic risk factors of diabetes mellitus among long-term survivors of childhood cancer.

METHODS

Adult survivors of childhood cancer from the Childhood Cancer Survivor Study (CCSS) Original Cohort (n = 5,083; 383 with diabetes) were used to conduct a discovery genome-wide association study. Replication was performed using the CCSS Expansion (n = 2,588; 40 with diabetes) and the St Jude Lifetime (SJLIFE; n = 3,351; 208 with diabetes) cohorts. Risk prediction models, stratified on exposure to abdominal radiation, were calculated using logistic regression including attained age, sex and body mass index, diagnosis, alkylating chemotherapy, age at cancer diagnosis, and a polygenic risk score (PRS) on the basis of 395 diabetes variants from the general population. Area under the receiver operating characteristic curve (AUC) was calculated for models on the basis of traditional risk factors, clinical risk factors, and PRS.

RESULTS

There was a genome-wide significant association of rs55849673-A with diabetes among survivors (odds ratio, 2.9; 95% CI, 2.0 to 4.2; P = 3.7 × 10^-8), which is related to expression of ERCC6L2 in the Genotype-Tissue Expression project. The association of rs55849673-A was observed largely among survivors not exposed to abdominal radiation (odds ratio = 3.5, P = 1.1 × 10^-7) and the frequency of rs55849673-A was consistently higher among diabetic survivors in the CCSS Expansion and SJLIFE cohorts. Risk prediction models including traditional diabetes risk factors, clinical risk factors and PRS had an optimism-corrected AUC of 0.801, with an AUC of 0.751 in survivors treated with abdominal radiation versus 0.813 in survivors who did not receive abdominal radiation.

CONCLUSION

There is evidence for a novel locus of diabetes among survivors not exposed to abdominal radiation. Further refinement and validation of clinic-based risk prediction models for diabetes among long-term survivors of childhood cancer is warranted.

1446Forgoing needed medical care among long-term survivors of childhood cancer: Racial/ethnic-insurance disparities

Background

Among adult childhood cancer survivors, the relationship between race/ethnicity and health insurance status, as a contributor to disparities in healthcare utilization, is poorly understood.

Methods

We examined racial/ethnic-related disparities by insurance status in “forgoing needed medical care in the last year due to finances” using 3,964 adult childhood cancer survivors (3310 non-Hispanic/Latinx White, 562 non-Hispanic/Latinx Black, and 92 Hispanic/Latinx) participating in the St. Jude Lifetime Cohort Study (SJLIFE). Multivariable logistic regression analyses, guided by Andersen’s Healthcare Utilization Model, were adjusted for “predisposing” (age, sex, childhood cancer diagnosis, cancer treatment, surgery, and treatment era) and “need” (perceived health status) factors. Additional adjustment for income/education and chronic health conditions was considered.

Results

The risk of forgoing care was highest among non-Hispanic/Latinx Blacks and lowest among Hispanics/Latinxs for each insurance status. Among privately-insured survivors, relative to non-Hispanic/Latinx Whites, non-Hispanic/Latinx Blacks were more likely to forgo care (adjusted OR: 1.82, 95% CI: 1.30–2.54): this disparity remained despite additional adjustment for income/education (adjusted OR: 1.43, 95% CI: 1.01–2.01). In contrast, publicly-insured survivors, regardless of race/ethnicity, had similar risk of forgoing care as privately-insured non-Hispanic/Latinx Whites. All uninsured survivors had high risk of forgoing care. Additional adjustment for chronic health conditions did not alter these results.

Conclusions

The findings of this study show that provision of public insurance to all childhood cancer survivors may diminish racial/ethnic disparities in forgoing care that exist among the privately-insured and reduce the risk of forgoing care among uninsured survivors to that of privately-insured non-Hispanic/Latinx Whites.

Key messages

Providing publicly funded health insurance coverage to childhood cancer survivors can reduce disparities in forgoing medical care.

A Novel Locus Predicts Spermatogenic Recovery among Childhood Cancer Survivors Exposed to Alkylating Agents

Exposure to high doses of alkylating agents is associated with increased risk of impaired spermatogenesis among nonirradiated male survivors of childhood cancer, but there is substantial variation in this risk. Here we conducted a genetic study for impaired spermatogenesis utilizing whole-genome sequencing data from 167 nonirradiated male childhood cancer survivors of European ancestry from the St. Jude Lifetime Cohort treated with cyclophosphamide equivalent dose (CED) ≥4,000 mg/m². Sperm concentration from semen analysis was assessed as the primary outcome. Common variants (MAF > 0.05) were adjusted for age at cancer diagnosis, CED, and top principal components. Rare/low-frequency variants (MAF ≤ 0.05) were evaluated jointly by various functional annotations and 4-kb sliding windows. A novel locus at 7q21.3 containing TAC1/ASNS was associated with decreased sperm concentration (rs7784118: P = 3.5 × 10^-8). This association was replicated in two independent samples of SJLIFE survivors of European ancestry, including 34 nonirradiated male survivors treated with 0 < CED < 4,000 mg/m² (P = 3.1 × 10^-4) and 24 male survivors treated with CED ≥4,000 mg/m² and radiotherapy <40 Gray (P = 0.012). No association was observed among survivors not exposed to alkylating agents included in the CED (P > 0.29). rs7784118 conferred 3.48- and 9.73-fold increases in risk for clinically defined oligospermia and azoospermia and improved prediction of normospermic, oligospermic, and azoospermic states by 13.7%, 5.3%, and 21.7%. rs7784118 was associated with decreased testosterone level, increased levels of follicle stimulating and luteinizing hormones, and 8.52-fold increased risk of Leydig cell failure. Additional research is warranted to determine how this SNP influences spermatogenesis and to assess its clinical utility in characterizing high-risk survivors and guiding intervention strategies. SIGNIFICANCE: The identified genetic markers harbor potential clinical utility in characterizing high-risk survivors and guiding intervention strategies including pretreatment patient counseling and use of fertility preservation services.

Clinical and genetic risk factors for radiation-associated ototoxicity: A report from the childhood cancer survivor study and the St. Jude Lifetime Cohort

10550

Background: Cranial radiation therapy (CRT) for pediatric cancer often results in ototoxicity in the form of hearing loss and tinnitus. We sought to identify clinical determinants and genetic risk factors for ototoxicity among adult survivors of pediatric cancer treated with cranial radiation. Methods: Relationships between age at last observation, sex, cumulative CRT dose and self-reported ototoxicity were evaluated for hearing loss and tinnitus among 1,991 (tinnitus) and 2,198 (hearing loss) survivors in the Childhood Cancer Survivor Study who received CRT. Logistic regression evaluated associations with non-genetic risk factors and comorbidities as well as SNP dosages in GWAS of CRT-related tinnitus (cases: 146; controls: 1,845) and hearing loss (cases: 270; controls: 1,928). Results: Males were more likely to report CRT-related tinnitus (9.4% vs. 5.4%; p = 5.81x10−4) and hearing loss (14.0% vs. 10.7%; p = 0.02) than females after adjusting for dose and age at last observation. Survivors with tinnitus or hearing loss were more likely to experience persistent dizziness or vertigo (tinnitus: p < 2.00x10−16; hearing loss: p = 6.35x10−9), take antidepressants (tinnitus: p = 0.02; hearing loss: p = 0.01) and report poorer overall health (tinnitus: p = 9.40x10−7; hearing loss: p = 1.30x10−6) compared to survivors without tinnitus or hearing loss after age-adjustment. GWAS of CRT-related tinnitus revealed a prominent signal in chromosome 1 led by rs203248 (p = 1.50x10−9), while GWAS of CRT-related hearing loss identified rs332013 (p = 5.79x10−7) in chromosome 8 and rs67522722 (p = 7.78x10−7) in chromosome 6 as approaching genome-wide significance. Replication analysis in an independent cohort of pediatric cancer survivors (SJLIFE) indicated that rs67522722, intronic to ATXN1, a gene associated with the neurodegenerative disorder spinocerebellar ataxia type 1, was significantly associated with CRT-related hearing loss (p = 0.03). Enrichment analysis and LD score regression with previous GWAS results of cisplatin-related hearing loss and tinnitus in testicular cancer survivors showed no detectable enrichment in genetic architecture with CRT-related hearing loss and tinnitus, respectively. Conclusions: Radiation-associated ototoxicity was associated with sex, several neuro-otological symptoms, increased antidepressant use and poorer self-reported health. GWAS of CRT-related hearing loss identified rs67522722 that was replicated in an independent cohort of pediatric cancer survivors.