Rash is a commonly reported adverse event during combination chemotherapy with carboplatin (CBDCA) plus pemetrexed (PEM). PEM in particular has been implicated in skin reactions, and short-course corticosteroid prophylaxis with dexamethasone is used to attenuate PEM-induced rash and to help manage chemotherapy-related nausea and vomiting. Because the incidence of thoracic cancers increases with age, investigators evaluated risk factors for rash in an elderly population receiving CBDCA plus PEM while on dexamethasone prophylaxis.
This was a retrospective assessment of patients aged 65 years and older who had thoracic cancer and received CBDCA plus PEM-based treatment with dexamethasone prophylaxis. The analysis included 109 patients. The primary analysis focused on factors associated with the occurrence of any-grade rash during the first chemotherapy cycle; secondary analyses examined factors associated with any-grade rash across all treatment cycles and changes in eosinophil counts associated with rash onset.
Dexamethasone was administered at 4 mg twice daily for 3 days as prophylaxis. This regimen was applied to attenuate PEM-associated rash and served as standard supportive care in the cohort under study.
Primary endpoint: identification of factors associated with incidence of any-grade rash during the first treatment cycle.
Secondary endpoints: identification of factors associated with any-grade rash during any treatment cycle and evaluation of change in eosinophil count between baseline and the closest laboratory assessment after rash onset.
Statistical methods reported in the abstract included multivariable logistic regression to estimate adjusted odds ratios and 95% confidence intervals for factors associated with rash occurrence.
During the first treatment cycle, the incidence of any-grade rash was 18.3%. Grading distribution in the first cycle was: grade 1, 11.9%; grade 2, 3.7%; and grade 3, 2.8%.
When considering all treatment cycles, the overall incidence of any-grade rash was 20.2%, with grade-specific rates of 12.8% (grade 1), 4.6% (grade 2), and 2.8% (grade 3). Most rash events (90.9%) first appeared during the first cycle of therapy.
In multivariable logistic regression analyses, a history of prior epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) therapy was associated with a lower risk of developing rash during CBDCA plus PEM chemotherapy with dexamethasone prophylaxis. Reported adjusted odds ratios (95% confidence intervals) and p values were:
No other specific risk factors are reported in the abstract as having been significant in multivariable models.
The study examined change in eosinophil counts between baseline and the closest evaluation after rash onset. The abstract reports that the change in eosinophil level from baseline to the closest evaluation after rash development was not significant. No numerical eosinophil values or detailed timing of laboratory assessments are provided in the abstract.
In this retrospective cohort of elderly patients (≥65 years) with thoracic cancer receiving CBDCA plus PEM and dexamethasone prophylaxis, prior exposure to EGFR-TKI therapy was associated with a reduced odds of developing treatment-associated rash. Most rashes occurred during the first cycle, underscoring the importance of early monitoring after initiating therapy. The absence of a significant eosinophil change suggests that eosinophilia was not a detectable biomarker of rash in this dataset, at least as assessed by the reported comparisons.
Clinicians treating elderly patients with CBDCA plus PEM may consider prior EGFR-TKI exposure as a factor associated with lower rash risk, but this observation should be interpreted in the context of the study design and limitations described below.
Key limitations from the abstract include retrospective design and limited reporting in the abstract regarding other covariates included in multivariable models, baseline patient characteristics, duration and timing of follow-up, and detailed laboratory data. The abstract does not report additional potential confounders, sample size calculations, or external validation. These limitations restrict causal inference and generalizability; details beyond what is provided in the abstract were not reported in the source.
Among 109 elderly patients with thoracic cancer treated with CBDCA plus PEM and dexamethasone prophylaxis, any-grade rash occurred in about one-fifth of patients, most commonly in the first cycle. Prior EGFR-TKI treatment was associated with a significantly lower risk of rash (adjusted ORs ≈0.17–0.18, p=0.04). No significant changes in eosinophil counts were associated with rash development according to the abstract. Further prospective work or larger datasets would be needed to confirm these findings and to explore mechanisms.