Andreana N. Holowatyj, Ph.D., MS Assistant Professor of Medicine and Cancer Biology from Vanderbilt University Medical Center, Vanderbilt-Ingram Cancer Center discusses Spectrum of Somatic Cancer Gene Variations Among Adults With Appendiceal Cancer by Age at Disease Onset.
Instract
Significance:
The incidence of appendiceal cancer (AC) is growing with unknown etiologies, especially among individuals younger than 50 years of age (early onset of AC). In patients with early-onset AC, the unique spectrum of somatic cancer gene variations is largely undetermined.
Target:
To classify the frequency of somatic variations and genomic trends in early-onset (<50 years of age) vs late-onset (<50 years of age) AC patients.
Plan, environment, and participants: This cohort study included individuals diagnosed with pathologically confirmed AC aged 18 years and older. The International Clinicogenomic Data Sharing Consortium American Association for Cancer Research Project Genomics Proof Neoplasia Knowledge Exchange reported cases with clinical-grade targeted sequencing data from January 1, 2011, to December 31, 2019. (GENIE). From May to September 2020, data analysis was performed.
Exposures: Exposures
Age at onset of illness.
Key results and measures: The prevalence and range of somatic variance are determined in patients with AC. Using multivariable logistic regression with adjustment for sex, race/ethnicity, histological subtype, sequencing core, and sample type, variance comparisons were examined between early-onset and late-onset AC.
Outcomes:
A total of 385 individuals with AC were included in this study (mean [SD] age at diagnosis, 56.0 [12.4] years; 187 [48.6 percent] males; 306 [79.5 percent] non-Hispanic White individuals), and 109 patients (28.3 percent) were diagnosed with early-onset AC. Race/ethnicity ranged by age at disease onset; a greater proportion of early-onset versus late-onset cases is accounted for by non-Hispanic Black individuals (9 of 109 [8.3 percent] vs 11 of 276 [4.0 percent]; P = 0.04). Patients with early-onset AC have slightly higher chances of presenting with nonsilent differences in PIK3CA, SMAD3, and TSC2 compared to patients 50 years of age or older at diagnosis (PIK3CA: odds ratio [OR], 4.58; 95 percent CI, 1.72-12.21; P = .002; SMAD3: OR, 7.37; 95 percent CI, 1.24-43.87; P = .03; TSC2: OR, 12.43; 95 percent CI, 1.03-149.59; P = .047). Patients with early-onset AC, on the other hand, had a 60% decreased risk of presenting with non-silent GNAS differences compared to patients with late-onset AC (OR, 0.40; 95% CI, 0.21-0.76, P = .006). By histologic subtype, young patients with appendix mucinous adenocarcinoma had a 65% decrease in the chances of GNAS variance relative to late-onset patients in the modified models (OR, 0.35; 95% CI, 0.15-0.79; P = .01). Similarly, patients with early-onset nonmucinous appendiceal adenocarcinomas had a 72% decrease in GNAS variance odds relative to late-onset cases, although these results did not achieve significance (OR, 0.28; 95% CI, 0.07-1.14; P = .08). GNAS and TP53 differences in early-onset and late-onset cases (P < .05) were mutually exclusive in its.
Conclusions and Pertinence:
In the study, relative to AC diagnosed among older individuals, AC diagnosed among younger individuals had a distinct genomic landscape. Specifically for younger patients, the creation of therapeutic modalities that target these unique molecular features can produce clinical implications.