Volumetric Modulated Arc Therapy Improves Outcomes in Definitive Radiochemotherapy for Anal Cancer Whilst Reducing Acute Toxicities and Increasing Treatment Compliance

Jacqueline Possiel; Hanne Elisabeth Ammon; Manuel Guhlich; Lena-Christin Conradi; Michael Ghadimi; Hendrik Andreas Wolff; Markus Anton Schirmer; Stephan Samel; Michael Mügge; Stefan Rieken; Martin Leu; Leif Hendrik Dröge

doi:10.3390/cancers13112533

Volumetric Modulated Arc Therapy Improves Outcomes in Definitive Radiochemotherapy for Anal Cancer Whilst Reducing Acute Toxicities and Increasing Treatment Compliance

Cancers (Basel). 2021 May 21;13(11):2533. doi: 10.3390/cancers13112533.

Affiliations

¹ Department of Radiotherapy and Radiation Oncology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany.
² Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, 37075 Göttingen, Germany.
³ University Medical Center Göttingen, 37075 Göttingen, Germany.
⁴ Department of Radiology, Nuclear Medicine and Radiotherapy, Radiology Munich, 80333 Munich, Germany.
⁵ Department of Radiotherapy and Radiation Oncology, University Medical Center Regensburg, 93053 Regensburg, Germany.
⁶ Praxis für Koloproktologie und chirurgische Endoskopie, Waldweg 1, 37073 Göttingen, Germany.

Abstract

Background: Intensity-modulated radiotherapy (IMRT) is the standard of care in chemoradiotherapy (CRT) for anal cancer. Until now, only a limited number of studies have analyzed the results with VMAT (volumetric modulated arc therapy). We conducted a retrospective study on patients treated at our institution.

Patients and methods: We included patients who received curative CRT for anal cancer. We compared VMAT-treated and 3DCRT (3D conformal radiotherapy)-treated patients. We analyzed toxicities (acute: CTCAE criteria; late: LENT/SOMA criteria), treatment compliance, overall survival, cancer-specific survival (CSS), distant control (DC), and locoregional control.

Results: A total of 149 patients (3DCRT: n = 87, VMAT: n = 62) were included. The median follow-up was longer in 3DCRT-treated patients (3DCRT: 61.3 months; VMAT: 39.1 months; p < 0.05). VMAT-treated patients had more G3 tumors (3DCRT: 12/87 (13.8%); VMAT: 18/62 (29.0%), p < 0.001). VMAT reduced acute toxicities ≥grade 3 (3DCRT: n = 48/87 (55.2%); VMAT: n = 11/62 (17.7%), p < 0.001). VMAT improved treatment compliance (less interruptions/delays) (3DCRT: 37/87, 42.5%; VMAT: 4/62, 6.5%; p < 0.001), provided a shorter median overall treatment time (3DCRT: 41 days; VMAT: 38 days; p = 0.02), and gave a higher median absolute 5-fluorouracil dose (3DCRT: 13,700 mg; VMAT: 14,400 mg; p = 0.001). Finally, we found improved CSS (p = 0.02; 3DCRT: 81.9% at 3 years; VMAT: 94.1% at 3 years) and DC (p = 0.01; 3DCRT: 89.4% at 3 years; VMAT: 100.0% at 3 years) with VMAT.

Summary: Our study is the first to demonstrate improved treatment compliance and outcomes with VMAT for anal cancer. Previous studies have indicated that organs at risk sparing might be more improved with the use of VMAT vs. with conventional IMRT. Future studies should address whether these advantages lead to a further reduction in CRT-associated morbidity.

Keywords: 3D conformal radiotherapy; acute toxicity; anal cancer; hematologic toxicity; late toxicity; radiochemotherapy; survival; treatment compliance; volumetric modulated arc therapy.