Intensity modulated radiation therapy versus conventional radiation for anal cancer in the Veterans Affairs system
Menée à partir de données portant sur 779 patients atteints d'un carcinome épidermoïde de l'anus de stade localement avancé diagnostiqué entre 2000 et 2015 et traité par chimioradiothérapie concomitante, cette étude évalue, par rapport à une radiothérapie conventionnelle, l'intérêt d'une radiothérapie avec modulation d'intensité pour réduire la toxicité du traitement, le risque d'ostomie ou le taux de chimiothérapies incomplètes, et améliorer la survie des patients
Background : Compared to conventional radiation therapy, intensity modulated radiation therapy (IMRT) may reduce acute toxicity from anal cancer treatment, potentially leading to improved long-term outcomes. We analyze the effect of IMRT on short- and long-term outcomes among a large sample of US veterans. Methods : From a national Veterans Affairs database we identified 779 patients (403 conventional RT, 376 IMRT) with locally advanced anal squamous cell carcinoma diagnosed between 2000-2015 and treated with concurrent chemoradiotherapy. Radiation treatment planning and dosimetric constraints were not standardized across patients. We analyzed the effect of IMRT on short-term outcomes (acute toxicity, treatment breaks, and incomplete chemotherapy) and long-term outcomes (survival and ostomy placement) in multivariable logistic regression, Fine-Gray, and frailty models, adjusting for potential confounders. Results : IMRT was associated with decreased radiation treatment breaks ≥ 5 days (odds ratio [OR] 0.58, 95% CI 0.37-0.91, p=0.02), increased rates of receiving 2 cycles of mitomycin C chemotherapy (OR 2.04, 95% CI 1.22-3.45, p=0.007), increased rates of receiving 2 cycles of any chemotherapy (OR 3.45, 95% CI 1.82-6.25, p<0.001), and decreased risk of ostomy related to tumor recurrence or progression (subdistribution hazard ratio 0.60, 95% CI 0.37-0.99, p=0.045). IMRT was not associated with a decrease in grade 3-4 hematologic toxicity (p=0.79), hospitalization for gastrointestinal toxicity (p=0.59), or cancer-specific survival (p=0.18). Conclusion : Among a large sample of US veterans with anal cancer, IMRT was associated with higher rates of receiving 2 chemotherapy cycles, decreased radiation treatment breaks, and decreased rates of ostomy placement. IMRT appears to offer substantial benefits over conventional RT to patients undergoing concurrent chemoradiotherapy for anal cancer.
https://www.redjournal.org/article/S0360-3016(18)30895-2/fulltext 2018