Pelvic Lymph Node Irradiation Including Pararectal Sentinel Nodes for Prostate Cancer Patients

Abstract

We aimed to assess the dosimetric impact of advanced delivery radiotherapy techniques using either intensity modulated x-ray beams (IMXT), volumetric modulated arc therapy (VMAT), or intensity modulated proton therapy (IMPT), for high-risk prostate cancer patients with sentinel nodes in the pararectal region. Twenty high-risk prostate cancer patients were included in a prospective trial evaluating sentinel nodes on pelvic SPECT acquisition. To be eligible for the dosimetric study, patients had to present with pararectal sentinel nodes usually not included in the clinical target volume encompassing the pelvic lymph nodes. Radiotherapy-plans including the prostate, the seminal vesicles, and the pelvic lymph nodes with the pararectal sentinel nodes were optimized for 6 eligible patients. IMXT and IMPT were delivered with 7 and 3 beams respectively and VMAT with 2 arcs. Results were assessed with Dose-Volume Histograms and predictive normal tissue complication probabilities (NTCPs) models between the three competing treatment modalities aiming to deliver a total dose of 50.4 Gy in 1.8 Gy daily fractions. Target coverage was optimized with IMPT when compared to IMXT and VMAT.Coverage of the sentinel node was slightly better with IMXT (D 98% 5 57.3  5.1 Gy) when compared with VMAT (D 98% 5 56.2  4.1 Gy). The irradiation of rectal, bladder, small bowel, and femoral heads volumes was significantly reduced with IMPT when compared to IMXT and VMAT. NTCPs rates for rectal and bladder  grade-3 late toxicity were better with IMPT (0.4  0.0% and 0.0  0.0%) compared with IMXT (4.6  3.3% and 1.4  1.1%), and VMAT (4.5  4.0% and 1.6  1.6%), respectively. Acceptable dose-volume distributions and low rectal and urinary NTCPs were estimated to geometrically complex pelvic volumes such as the ones proposed in this study using IMXT, VMAT and IMPT. IMPT succeeded, however, to propose the best physical and biological treatment plans compared to both X-ray derived plans.

Dosimetric and radiobiological impact of intensity modulated proton therapy and RapidArc planning for high‐risk prostate cancer with seminal vesicles

“…RapidArc (a form of volumetric modulated arc therapy (VMAT) implemented by Varian Medical Systems, Palo Alto, CA) and intensity modulated proton therapy (IMPT) are two most recent EBRT modalities that are used to treat prostate cancer. 1,2 One of the fundamental differences between these two techniques is that mega-voltage X-rays (photons) are used for RapidArc delivery, whereas protons are used for IMPT. Several researchers [2][3][4][5][6][7][8][9][10] have investigated the dosimetric impact of photon and proton therapy for the prostate cancer.…”

“…1,2 One of the fundamental differences between these two techniques is that mega-voltage X-rays (photons) are used for RapidArc delivery, whereas protons are used for IMPT. Several researchers [2][3][4][5][6][7][8][9][10] have investigated the dosimetric impact of photon and proton therapy for the prostate cancer. Earlier studies 4-10 using proton therapy were mostly focused on double scattering and uniform scanning.…”

“…External beam radiation therapy (EBRT) continues to be one of the most commonly used treatment techniques for cancer treatment. RapidArc (a form of volumetric modulated arc therapy (VMAT) implemented by Varian Medical Systems, Palo Alto, CA) and intensity modulated proton therapy (IMPT) are two most recent EBRT modalities that are used to treat prostate cancer . One of the fundamental differences between these two techniques is that mega‐voltage X‐rays (photons) are used for RapidArc delivery, whereas protons are used for IMPT.…”

Haute Couture or Ready-To-Wear? Tailored Pelvic Radiotherapy for Prostate Cancer Based on Individualized Sentinel Lymph Node Detection

“…Trying to irradiate all possible areas of lymphatic drainage in all patients may increase intestinal toxicity. Using IMRT, coverage of PR SLN is feasible without increasing the dose to the intestine [30]. Studies on a limited number of patients revealed the outcomes of SLN-based pelvic radiotherapy in prostate cancer [18,31].…”

Multiple Computed Tomography Robust Optimization to Account for Random Anatomic Density Variations During Intensity Modulated Proton Therapy

“… 1 , 2 The finite range of proton beams eliminates exit dose, 3 resulting in a reduction in integral dose of radiation and better sparing of organs at risk (OARs) in many cases. 4 , 5 , 6 , 7 , 8 , 9 However, the range of proton beams is subject to uncertainties that must be understood and accounted for in the treatment plan to avoid compromising clinical goals. 10 …”