Neo-adjuvant chemo-radiation of rectal cancer with Volumetric Modulated Arc Therapy: summary of technical and dosimetric features and early clinical experience

Abstract

BackgroundTo report about initial technical and clinical experience in preoperative radiation treatment of rectal cancer with volumetric modulated arcs with the RapidArc® (RA) technology.MethodsTwenty-five consecutive patients (pts) were treated with RA. All showed locally advanced rectal adenocarcinoma with stage T2-T4, N0-1. Dose prescription was 44 Gy in 22 fractions (or 45 Gy in 25 fractions). Delivery was performed with single arc with a 6 MV photon beam. Twenty patients were treated preoperatively, five did not receive surgery. Twenty-three patients received concomitant chemotherapy with oral capecitabine. A comparison with a cohort of twenty patients with similar characteristics treated with conformal therapy (3DC) is presented as well.ResultsFrom a dosimetric point of view, RA improved conformality of doses (CI95% = 1.1 vs. 1.4 for RA and 3DC), presented similar target coverage with lower maximum doses, significant sparing of femurs and significant reduction of integral and mean dose to healthy tissue. From the clinical point of view, surgical reports resulted in a down-staging in 41% of cases. Acute toxicity was limited to Grade 1-2 diarrhoea in 40% and Grade 3 in 8% of RA pts, 45% and 5% of 3DC pts, compatible with known effects of concomitant chemotherapy. RA treatments were performed with an average of 2.0 vs. 3.4 min of 3DC.ConclusionRA proved to be a safe, qualitatively advantageous treatment modality for rectal cancer, showing some improved results in dosimetric aspects.

Volumetric intensity-modulated arc therapy vs. 3-dimensional conformal radiotherapy for primary chemoradiotherapy of anal carcinoma

“…Previous studies of anal carcinoma [26] and other tumor types [19][20][21][22] have demonstrated the treatment planning advantages of the modern radiation technique VMAT, such as fast treatment application, highly conformal dose distributions and uncompromised target volume coverage. Despite these promising results at the planning level, there are currently no data on the potential clinical benefit of VMAT with regard to reduced toxicity and favorable outcomes for patients with anal carcinoma.…”

“…In addition to technical and dosimetric information, Richetti et al [21] investigated early clinical data from patients receiving preoperative CRT for locally advanced rectal cancer. In their study, VMAT showed, in line with our results, promising potential for improved OAR sparing and acute toxicity reduction with grade 1-2 diarrhea occurring in 40 % and grade 3 in 8 % of VMAT patients versus 45 and 5 % of 3DCRT patients.…”

“…Moreover, locoregional control (LRC) and the treatment effectiveness were maintained when combined with chemotherapy [18]. Recently, an even more advantageous treatment modality, volumetric intensity-modulated arc therapy (VMAT), was introduced into clinical practice after promising results at the planning level were reported for several tumor entities [19][20][21][22][23][24][25]. In a planning study of anal carcinoma, Clivio et al [26] showed highly conformal dose distributions with improved organ at risk (OAR) and healthy tissue sparing.…”

Volumetric modulated arc therapy: a review of current literature and clinical use in practice

“…They found similar PTV coverage, but significantly lower mean doses to small bowel and integral dose in the IMAT plans. Richetti et al [79] reported on their technical and clinical experience of 25 patients with locally advanced rectal cancer treated with VMAT and performed a planning comparison with a matched cohort of patients who underwent conventional conformal radiotherapy. Although PTV coverage was similar, single arc VMAT achieved significantly superior dose conformity with a trend to improvement in homogeneity and improved OAR sparing (small bowel, femora and healthy tissue).…”

The Impact of Novel Radiation Treatment Techniques on Toxicity and Clinical Outcomes in Rectal Cancer

“…VMAT has been compared to IMRT or 3DCRT in a few retrospective dosimetric studies (17, 18, 21, 51). The conformity index was improved with VMAT compared to 3DCRT.…”