Page 33 - ARNM-3-3

Advances in Radiotherapy
& Nuclear Medicine Brachytherapy versus external beam in local dose escalation

predefined eligibility criteria, 505 articles were excluded, three selected studies were retrospective and focused on
resulting in seven studies being included for full analysis. dosimetric comparisons.
Ultimately, three randomized controlled trials met the
inclusion criteria. 13-15 3.3.2. Results of individual studies
In the study by Pinzi et al., intensity-modulated radiotherapy
3.2.2. Results of individual studies (IMRT) boost plans demonstrated significantly greater
The study population comprised 703 patients, with dose homogeneity compared to IRT boost plans. This
349 receiving an IRT boost and 354 receiving an EBRT was reflected in differences in maximum and minimum
boost. The median age across both cohorts was 68 years. dose values (p=0.001 and p<0.0001, respectively), V85Gy
The groups were also comparable in terms of National and V95Gy (p=0.0002 and p=0.0001), as well as in the
Comprehensive Cancer Network risk classification, with conformation number and conformity index (p<0.0001
all patients categorized as intermediate- or high-risk, and p=0.0003, respectively). However, IRT was associated
except for a small proportion (<10%) of low-risk patients with significantly improved sparing of OARs, with the
included in the study by Hoskin et al. 13-15 mean percentage of the prescription dose delivered to the
rectum, bowel, and bladder being 47.95%, 39.12%, and
Across all studies, the use and duration of androgen
deprivation therapy were consistent between the IRT 30.95%, respectively, compared to 89.54%, 91.15%, and
78.57% for IMRT.
16
and EBRT groups. EBRT was delivered using three-
dimensional conformal radiotherapy in two studies 13,14 Cilla et al. compared HDR-IRT and volumetric
17
and a two-dimensional technique in one. The radiation modulated arc therapy (VMAT) plans using an anatomy-
14
field was primarily limited to the prostate, except in the based optimization module (PO-VMAT) and a full-inverse
ASCENDE-RT trial, where the pelvic region was also planning module (FI-VMAT) for vaginal cuff treatment in
included. IRT techniques and doses varied among the postoperative endometrial cancer. The focus was on dose
studies: two studies 14,15 used low-dose-rate IRT, while one distribution, target coverage, and normal tissue sparing.
used high-dose-rate (HDR) IRT. The biologically effective PO-VMAT achieved the best target coverage with a D99%
13
dose, calculated for prostate cancer with an α/β ratio of of 112.6%, compared to 106.0% for FI-VMAT and 107.2%
1.5, was higher in the IRT arm across all studies: 175 Gy for HDR-IRT (p=0.002 and p=0.015). HDR-IRT plans
versus 154 Gy (Sathya et al. ), 215 Gy versus 156 Gy, and showed significant dose heterogeneity, with D1% reaching
15
222 Gy versus 182 Gy (ASCENDE-RT). 250% for the clinical target volume (CTV) and 235% for the
PTV. PO-VMAT had mean CTV and PTV doses of 119.8%
The mean 7-year biochemical progression-free survival
(b-PFS) was 76% in the IRT group compared to 61.5% in and 110.0%, respectively, compared to 144.2% for both in
HDR-IRT (p=0.001 for both). VMAT plans also achieved
the EBRT group. 13,14 Long-term b-PFS rates at 10.6 and better sparing of OARs, with rectum D0.1cc and bladder
14 years were 67% and 53% for the IRT group, versus 38% D0.1cc reduced by 14% (p<0.001) and 15% (p=0.005),
16
and 30% for the EBRT group, respectively, demonstrating respectively, compared to HDR-IRT. However, HDR-IRT
a significant benefit associated with the IRT boost. delivered significantly lower doses to the femoral heads
The mean OS at 7 years was 83.5% for IRT and 85% for (D0.1cc: 12.2%) compared to FI-VMAT (24.7%, p=0.013)
EBRT. 12,13 The 10.6- and 14-year OS rates were 80% and and PO-VMAT (24.3%, p=0.016). 17
33% for the IRT group, compared to 87% and 23% for the Grelewicz et al. reported that EBRT plans provided
18
EBRT group. 15
superior target coverage and improved dose homogeneity
No significant differences were reported between compared to HDR-IRT, with V90 values of 95% for EBRT
the two techniques in terms of late gastrointestinal or versus 50 – 58% for HDR-IRT. Nevertheless, HDR-IRT
genitourinary toxicities. demonstrated lower high-dose exposure to OARs, with
D0.1cc, D1.0cc, and D2.0cc values reduced by 2% to 38%
3.3. Endometrial cancer compared to EBRT plans. 18
3.3.1. Study selection
3.4. Cervix cancer
The literature search yielded 286 records. After removing
duplicates and screening for relevance, 200 abstracts were 3.4.1. Study selection
selected for further assessment. Based on the predefined The literature search identified 3,305 records. After
inclusion criteria, 183 articles were excluded, resulting removing duplicates and screening for relevance, 827
in 17 studies being reviewed in full. Ultimately, three abstracts were selected for further evaluation. Based on the
retrospective studies met the eligibility criteria. 16-18 All predefined inclusion criteria, 753 articles were excluded,

Volume 3 Issue 3 (2025) 25 doi: 10.36922/ARNM025160017