Brachytherapy boost in anal canal cancer - A GEC ESTRO PDR task force meta-analysis

Pierre Annede; Marjorie Ferre; Christian Kirisits; Bradley R Pieters; Maximilian Schmid; Vratislav Strnad; Henrike Westerveld; Cyrus Chargari

doi:10.1016/j.ctro.2023.100589

Brachytherapy boost in anal canal cancer - A GEC ESTRO PDR task force meta-analysis

Clin Transl Radiat Oncol. 2023 Jan 30:39:100589. doi: 10.1016/j.ctro.2023.100589. eCollection 2023 Mar.

Authors

Pierre Annede¹, Marjorie Ferre², Christian Kirisits³, Bradley R Pieters^{4

5}, Maximilian Schmid³, Vratislav Strnad⁶, Henrike Westerveld⁷, Cyrus Chargari⁸

Affiliations

¹ Center of Radiation Oncology, French Red Cross, Toulon, France, Paris Saclay University, Paris, France.
² Department of Radiotherapy, Paoli Calmettes Institute, Marseille, France.
³ Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria.
⁴ Department of Radiation Oncology, Amsterdam University Medical Centers/University of Amsterdam, The Netherlands.
⁵ Cancer Center Amsterdam, Cancer Treatment and Quality of Life, Amsterdam, The Netherlands.
⁶ Department of Radiation Oncology, University Hospital Erlangen, Comprehensive Cancer Center Erlangen-EMN, Erlangen, Germany.
⁷ Department of Radiation Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands.
⁸ Department of Radiation Oncology, University Hospital Pitié-Salpêtrière - Assistance Publique des Hôpitaux de Paris - Paris Sorbonne University, France.

Abstract

Purpose: A meta-analysis is presented comparing clinical outcomes and toxicities between high dose rate (HDR) and pulsed dose rate (PDR) brachytherapy (BT) for anal cancer.

Methods and material: Retrospective or prospective clinical trials were identified on electronical databases. Data were collected per Preferred Reporting Items for Systematic Reviews and meta-Analyses guidelines. Pooled effect size for HDR and PDR BT were compared using subgroup analyses.

Results: Nine retrospective studies with a total of 481 patients treated were included of which 219 with HDR and 262 with PDR. Significant differences were observed between the two groups for baseline characteristics and treatment. The cumulative proportion of stage T3-T4 was lower in the HDR group, 0.15 [95 % confidence interval (CI) 0.07-0.29] vs 0.27 [95 %CI 0.09-0.57] in the LDR group, p < 0.001. Lower BT doses (in equivalent 2-Gy fraction dose) were given for patients in the HDR group, 11.9 Gy [95 %CI 8.2-15.5] vs 19.5 Gy [95 %CI 15.0-24.0] in the PDR group, p < 0.001. No significant differences were found for clinical outcomes or toxicities. The pooled effect size of the overall survival at 5 years for HDR and PDR was respectively 0.82 [95 %CI 0.70-0.94] and 0.82 [95 %CI 0.73-0.91], p > 0.99. The 5 years local control was 0.86 [95 % confidence interval (CI) 0.81-0.91] and 0.83 [95 %CI 0.77-0.89], p = 0.62. Cumulative toxicity-related colostomy proportion was 0.04 [95 %CI 0.02-0.09] and 0.03 [95 %CI 0.02-0.07], p = 0.85.

Conclusion: Both modalities provided a good profile of tolerance and are effective organ conservative strategies for patients with anal canal cancer. In parallel with ongoing developments to better determine the optimal fractionation and dose for HDR-BT treatments, especially in large tumors, PDR BT still has a crucial role for dose escalation strategy in advanced cases.

Keywords: Anal cancer; Brachytherapy; High-dose rate brachytherapy; Local control; Morbidity; Pulsed-dose rate brachytherapy; Toxicity.