A groundbreaking study presented at the 2024 ASH Annual Meeting has revealed that tobacco smoking significantly impacts the genetic landscape and progression of myelodysplastic syndromes (MDS), establishing a clear link between smoking habits and disease outcomes.
The research, conducted through The National Myelodysplastic Syndromes Natural History Study, analyzed data from 1,898 patients, with nearly equal distribution between smokers (979) and non-smokers (919). The study population comprised 61% males, with most patients falling between 70-79 years of age.
Genetic Mutations and Smoking Correlation
Researchers identified specific mutation patterns more prevalent in smokers compared to non-smokers. Notably, smokers showed higher rates of mutations in critical pathways:
- Chromatin modification (15.3% vs 10.9%, P = .001)
- RNA splicing (25.5% vs 18.6%, P < .001)
Individual high-risk mutations were significantly more common in smokers, including:
- ASXL1 (12% vs 8%, P < .01)
- SF3B1 (9% vs 6%, P < .05)
- U2AF1 (6% vs 3%, P < .05)
- ZRSR2 (2% vs 1%, P < .05)
Dose-Response Relationship and Disease Progression
The study revealed a striking dose-response relationship between smoking intensity and mutation frequency. Heavy smokers in the 90th percentile of pack-years demonstrated 3.5 times more mutations than non-smokers, while those in the 75th percentile showed 1.8 times more mutations.
Disease progression rates were significantly higher among long-term smokers:
- 27% five-year cumulative incidence for those smoking 20+ years (95% CI, 19%-36%)
- 18% for those smoking fewer than 20 years (95% CI, 13%-24%)
Impact on Survival Outcomes
The research also examined overall survival in both MDS and its precursor condition, clonal cytopenia of undetermined significance (CCUS). Smokers with CCUS showed significantly lower overall survival compared to non-smokers (HR, 1.91; 95% CI, 1.03-3.55; P = .04).
Clinical Implications
"The most important take-home point of this study is we, as physicians and hematologists, can initiate the smoking cessation counseling in patients who are first diagnosed with myelodysplastic syndrome," emphasized Dr. Sangeetha Venugopal from the Sylvester Comprehensive Cancer Center at the University of Miami.
The findings underscore the importance of smoking cessation as a crucial intervention point in MDS management. The clear correlation between smoking duration and mutation accumulation suggests that early cessation could potentially alter disease trajectory and improve patient outcomes.
Study Methodology
The research utilized standardized CDC definitions for smoking intensity:
- Light: Less than 10 pack-years
- Medium: Less than 29 pack-years
- Heavy: 30+ pack-years
Pack-years were calculated by multiplying the number of packs smoked per day by the number of years of smoking. The study's robust dataset included detailed information on diagnostic categories, medical history, comorbidity indices, cytogenetics, and comprehensive bone marrow assessments and gene sequencing.
