Intensity-Modulated Radiotherapy (IMRT) vs Helical Tomotherapy (HT) in Concurrent Chemoradiotherapy (CRT) for Patients with Anal Canal Carcinoma (ACC): an analysis of dose distribution and toxicities

Abstract

PurposeIntensity-modulated radiotherapy (IMRT) and helical tomotherapy (HT) have been adopted for radiotherapy treatment of anal canal carcinoma (ACC) due to better conformality, dose homogeneity and normal-tissue sparing compared to 3D-CRT. To date, only one published study compares dosimetric parameters of IMRT vs HT in ACC, but there are no published data comparing toxicities. Our objectives were to compare dosimetry and toxicities between these modalities.Methods and materialsThis is a retrospective study of 35 ACC patients treated with radical chemoradiotherapy at two tertiary cancer institutions from 2008–2010. The use of IMRT vs HT was primarily based on center availability. The majority of patients received fluorouracil (5-FU) and 1–2 cycles of mitomycin C (MMC); 2 received 5-FU and cisplatin. Primary tumor and elective nodes were prescribed to ≥54Gy and ≥45Gy, respectively. Patients were grouped into two cohorts: IMRT vs HT. The primary endpoint was a dosimetric comparison between the cohorts; the secondary endpoint was comparison of toxicities.Results18 patients were treated with IMRT and 17 with HT. Most IMRT patients received 5-FU and 1 MMC cycle, while most HT patients received 2 MMC cycles (p < 0.01), based on center policy. HT achieved more homogenous coverage of the primary tumor (HT homogeneity and uniformity index 0.14 and 1.02 vs 0.29 and 1.06 for IMRT, p = 0.01 and p < 0.01). Elective nodal coverage did not differ. IMRT achieved better bladder, femoral head and peritoneal space sparing (V30 and V40, p ≤ 0.01), and lower mean skin dose (p < 0.01). HT delivered lower bone marrow (V10, p < 0.01) and external genitalia dose (V20 and V30, p < 0.01). Grade 2+ hematological and non-hematological toxicities were similar. Febrile neutropenia and unscheduled treatment breaks did not differ (both p = 0.13), nor did 3-year overall and disease-free survival (p = 0.13, p = 0.68).ConclusionsChemoradiotherapy treatment of ACC using IMRT vs HT results in differences in dose homogenity and normal-tissue sparing, but no significant differences in toxicities.

Radiological assessment of anal cancer: an overview and update

“…The advent of new therapies, more and more personalized to the patients and the recent improvements of neoadjuvant therapies, radiotherapy and chemotherapy can cause a down staging of the lesion, such as to make operable lesions that were not resectable before treatment [ 12 – 14 ]. In addition, the choice of low-invasive surgery, with sphinter saving technique, increases the risk of recurrence.…”

“…[ 9 , 12 , 13 ] On the contrary, a delays in diagnosis might lead to an advance cancer stage at presentation with worst survival, [ 8 ]. The recent improvements of neoadjuvant therapies, radiotherapy and chemotherapy, can also down staging the lesion, as well as to allow a conservative treatment [ 9 – 14 ]. According to National Comprehensive Cancer Network (NCCN) Anal Carcinoma Guidelines the patients should be subjected to a careful clinical examination, including a digital rectal examination (DRE), an anoscopic examination, and palpation of inguinal nodes [ 15 ].…”

Neoadjuvant chemoradiotherapy delivered with helical tomotherapy under daily image guidance for rectal cancer patients: efficacy and safety in a large, multi-institutional series

“…This combination allows for a more precise definition of the planning target volume (PTV) and accurate irradiation. Dosimetric studies have shown that HT could reduce the doses delivered to the normal tissues in patients affected by lower gastrointestinal cancers (i.e., locally advanced rectal cancer or anal cancers) when compared with conventional 3D- conformal RT (De Bari et al 2018 ; Yang et al 2013 ) or IMRT (Yeung et al 2015 ). Clinical data on the role of HT in the treatment of locally advanced rectal cancer are available, but is mainly in the form of a small study which consisted of only a small cohort of 36 patients (Huang et al 2014 ).…”

Targeting Tumor Hypoxia in Radiotherapy: A Brief Review of Historical Background and Recent Progress

“…Mitomycin C lacks preferential selectivity for hypoxic cells; and, in clinical trials, it was administered once or twice during a radiotherapy course. [101] The ARO 95-06 randomized trial compared hyperfractionated accelerated chemoradiation with mitomycin C/5-fluorouracil (C-HART) with hyperfractionated accelerated radiation therapy (HART) alone in locally advanced head-and-neck cancer. Long-term results showed that C-HART remains superior to HART in terms of locoregional control and survival rates.…”