Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography-based Lymph Node Atlas for Salvage Radiotherapy in Patients with Recurrent Prostate Cancer: A Validation of the New NRG Oncology 2020 guideline.

BACKGROUND: Approximately 20-40% of patients with prostate cancer (PC) who undergo radical prostatectomy (RP) experience relapse, with the majority of these cases developing pelvic lymph node (LN) metastases. Taking new data from the prostate-specific membrane antigen (PSMA) positron emission tomography (PET) era into account, the Radiation Therapy Oncology Group (RTOG) 2009 contouring guideline for the pelvic LNs from 2009 was updated by the NRG Oncology group in 2020 (NRG 2020). OBJECTIVE: To evaluate and validate the updated NRG 2020 guideline with our established LN atlas. DESIGN, SETTING, AND PARTICIPANTS: We screened 1653 PSMA PET/computed tomography (CT) data sets for patients with biochemical relapse who underwent a PET scan between November 2012 and November 2017. After screening, we developed an LN atlas using data from 233 patients. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: We evaluated LN overlap (OL) with the RTOG 2009 and NRG 2020 contouring guidelines. OL was defined as within (>90%), partly within (10-90%), or outside (<10%). RESULTS AND LIMITATIONS: In comparison to the RTOG 2009 guideline, 403 (52%), 134 (17%), and 241 (31%) of the LNs were not, were partly, or were fully covered within the overall group, respectively. By contrast, using the NRG 2020 guideline, 302 (39%), 190 (24%), and 286 (37%) of the LNs were not, were partly, or were fully covered, respectively (p < 0.001). Limitations include the retrospective design with missing data and no histopathological confirmation of the PET results. CONCLUSIONS: The updated NRG 2020 contouring guideline improves coverage of the pelvic LNs in patients undergoing salvage radiation therapy. However, PET/CT should be considered whenever possible to ensure coverage of untypical LN spread. PATIENT SUMMARY: We compared the 2009 and 2020 guidelines on the radiation area for the pelvis for patients with recurrent prostate cancer that has spread to lymph nodes. The newer guideline provides better coverage of pelvic lymph nodes than the older one and is useful in planning radiation therapy. However, a scan of the pelvis using the newest technique should be considered for individual patients to ensure coverage of untypical lymph nodes.

Feasibility and Outcome of PSMA-PET-Based Dose-Escalated Salvage Radiotherapy Versus Conventional Salvage Radiotherapy for Patients With Recurrent Prostate Cancer.

INTRODUCTION: Prostate-specific membrane antigen-positron emission tomography-(PSMA-PET) imaging facilitates dose-escalated salvage radiotherapy (DE-SRT) with simultaneous-integrated boost (SIB) for PET-positive lesions in patients with prostate cancer (PC). Therefore, we aimed to compare toxicity rates of DE-SRT with SIB to conventional SRT (C-SRT) without SIB and to report outcome. MATERIALS AND METHODS: We evaluated 199 patients who were treated with SRT between June 2014 and June 2020. 101 patients received DE-SRT with SIB for PET-positive local recurrence and/or PET-positive lymph nodes. 98 patients were treated with C-SRT to the prostate bed +/- elective pelvic lymphatic pathways without SIB. All patients received PSMA-PET imaging prior to DE-SRT ([68Ga]PSMA-11: 45.5%; [18F]-labeled PSMA: 54.5%). Toxicity rates for early (<6 months) and late (>6 months) gastrointestinal (GI) toxicities rectal bleeding, proctitis, stool incontinence, and genitourinary (GU) toxicities hematuria, cystitis, urine incontinence, urinary obstruction, and erectile dysfunction were assessed. Further, we analyzed the outcome with disease-free survival (DFS) and prostate-specific antigen (PSA) response. RESULTS: The overall toxicity rates for early GI (C-SRT: 2.1%, DE-SRT: 1.0%) and late GI (C-SRT: 1.4%, DE-SRT: 5.3%) toxicities ≥ grade 2 were similar. Early GU (C-SRT: 2.1%, DE-SRT: 3.0%) and late GU (C-SRT: 11.0%, DE-SRT: 14.7%) toxicities ≥ grade 2 were comparable, as well. Early and late toxicity rates did not differ significantly between DE-SRT versus C-SRT in all subcategories (p>0.05). PSA response (PSA ≤0.2 ng/ml) in the overall group of patients with DE-SRT was 75.0% and 86.4% at first and last follow-up, respectively. CONCLUSION: DE-SRT showed no significantly increased toxicity rates compared with C-SRT and thus is feasible. The outcome of DE-SRT showed good results. Therefore, DE-SRT with a PSMA-PET-based SIB can be considered for the personalized treatment in patients with recurrent PC.

A survey among German-speaking radiation oncologists on PET-based radiotherapy of prostate cancer.

BACKGROUND: Positron emission tomography-(PET) has evolved as a powerful tool to guide treatment for prostate cancer (PC). The aim of this survey was to evaluate the acceptance and use of PET-especially with prostate-specific membrane antigen (PSMA) targeting tracers-in clinical routine for radiotherapy (RT) and the impact on target volume definition and dose prescription. METHODS: We developed an online survey, which we distributed via e-mail to members of the German Society of Radiation Oncology (DEGRO). The survey included questions on patterns of care of RT for PC with/without PET. For evaluation of doses we used the equivalent dose at fractionation of 2 Gy with α/ß = 1.5 Gy [EQD2(1.5 Gy)]. RESULTS: From 109 participants, 78.9% have the possibility to use PET for RT planning. Most centers use PSMA-targeting tracers (98.8%). In 39.5%, PSMA-PET for biochemical relapse after prior surgery is initiated at PSA ≥ 0.5 ng/mL, while 30.2% will perform PET at ≥ 0.2 ng/mL (≥ 1.0 ng/mL: 16.3%, ≥ 2.0 ng/mL: 2.3%, regardless of PSA: 11.7%). In case of PET-positive local recurrence (LR) and pelvic lymph nodes (LNs), 97.7% and 96.5% of the participants will apply an escalated dose. The median total dose in EQD2(1.5 Gy) was 70.00 Gy (range: 56.89-85.71) for LR and 62.00 Gy (range: 52.61-80.00) for LNs. A total number of ≤ 3 (22.0%) or ≤ 5 (20.2%) distant lesions was most often described as applicable for the definition as oligometastatic PC. CONCLUSION: PSMA-PET is widely used among German radiation oncologists. However, specific implications on treatment planning differ among physicians. Therefore, further trials and guidelines for PET-based RT are warranted.

Patterns of care for prostate cancer radiotherapy-results from a survey among German-speaking radiation oncologists.

BACKGROUND: Emerging moderately hypofractionated and ultra-hypofractionated schemes for radiotherapy (RT) of prostate cancer (PC) have resulted in various treatment options. The aim of this survey was to evaluate recent patterns of care of German-speaking radiation oncologists for RT of PC. METHODS: We developed an online survey which we distributed via e­mail to all registered members of the German Society of Radiation Oncology (DEGRO). The survey was completed by 109 participants between March 3 and April 3, 2020. For evaluation of radiation dose, we used the equivalent dose at fractionation of 2 Gy with α/ß = 1.5 Gy, equivalent dose (EQD2 [1.5 Gy]). RESULTS: Median EQD2(1.5 Gy) for definitive RT of the prostate is 77.60 Gy (range: 64.49-84.00) with median single doses (SD) of 2.00 Gy (range: 1.80-3.00), while for postoperative RT of the prostate bed, median EQD2(1.5 Gy) is 66.00 Gy (range: 60.00-74.00) with median SD of 2.00 Gy (range: 1.80-2.00). For definitive RT, the pelvic lymph nodes (LNs) are treated in case of suspect findings in imaging (82.6%) and/or according to risk formulas/tables (78.0%). In the postoperative setting, 78.9% use imaging and 78.0% use the postoperative tumor stage for LN irradiation. In the definitive and postoperative situation, LNs are irradiated with a median EQD2(1.5 Gy) of 47.52 Gy with a range of 42.43-66.00 and 41.76-62.79, respectively. CONCLUSION: German-speaking radiation oncologists' patterns of care for patients with PC are mainly in line with the published data and treatment recommendation guidelines. However, dose prescription is highly heterogenous for RT of the prostate/prostate bed, while the dose to the pelvic LNs is mainly consistent.

Increased heat shock protein 70 (Hsp70) serum levels and low NK cell counts after radiotherapy - potential markers for predicting breast cancer recurrence?

BACKGROUND: Breast cancer is the most common invasive tumor in women worldwide and the second cause of cancer-related deaths. After breast conserving surgery the tumor bed gets irradiated. Radiation-induced tumor cell death has been found to be associated with the release of damage-associated molecular patterns (DAMPs) including free Hsp70 that can stimulate inflammatory immune responses. Therefore, Hsp70 serum levels as well as the composition of lymphocyte subpopulations have been measured in breast cancer patients during therapy and in the follow-up period as potential predictors for clinical outcome. METHODS: The serum of 40 breast cancer patients, who received a breast-conserving surgery and adjuvant radiotherapy (RT) was examined for soluble, free Hsp70 using the R&D Human HSP70 DuoSet and lipHsp70 ELISA. Lymphocyte subpopulations and total lymphocyte counts were analysed by multiparameter flow cytometry in the peripheral blood. Blood samples were collected before (t1), after 30 Gy (t2) and 60 Gy (t3), 6 weeks (t4), 6 months (t5) and 1 year (t6) after RT. Clinical responses were assessed regularly up to 5 years after RT. RESULTS: Patients who developed a contralateral recurrence or metastases within the first 2 years after RT had significantly higher serum Hsp70 values at the end of RT (t3; p = 0.03) up to 6 weeks after RT (t4; p = 0.007) compared to patients who either remained disease-free or developed a secondary endometrial carcinoma. Clinicopathological parameters such as age, tumor size, grading and TNM-stage of the resected tumors, adjuvant chemotherapy and irradiation dose did not affect serum Hsp70 levels. Elevated free Hsp70 levels might be indicative for a chronic inflammatory response which could support tumor recurrence. Lymphocyte subpopulation analysis revealed lower NK cell counts after RT in recurrence/metastases patients as compared to disease-free patients. In contrast, no significant changes were observed in the proportion of T and B cells. CONCLUSION: Longitudinal elevated serum levels of free Hsp70 up to 6 weeks after RT and dropping NK cell counts might be predictive for an unfavourable prognosis in patients with breast cancer.

Effects of definitive and salvage radiotherapy on the distribution of lymphocyte subpopulations in prostate cancer patients.

BACKGROUND: Radiotherapy (RT) is an established treatment for patients with primary and recurrent prostate cancer. Herein, the effects of definitive and salvage RT on the composition of lymphocyte subpopulations were investigated in patients with prostate cancer to study potential immune effects. PATIENTS AND METHODS: A total of 33 prostate cancer patients were treated with definitive (n = 10) or salvage RT (n = 23) after biochemical relapse. The absolute number of lymphocytes and the distribution of lymphocyte subpopulations were analyzed by multiparameter flow cytometry before RT, at the end of RT, and in the follow-up period. RESULTS: Absolute lymphocyte counts decreased significantly after RT in both patient groups and a significant drop was observed in the percentage of B cells directly after RT from 10.1 ± 1.3 to 6.0 ± 0.7% in patients with definitive RT and from 9.2 ± 0.8 to 5.8 ± 0.7% in patients with salvage RT. In contrast, the percentages of T and natural killer (NK) cells remained unaltered directly after RT in both patient groups. However, 1 year after RT, the percentage of CD3+ T cells was significantly lower in patients with definitive and salvage RT. The percentage of regulatory T cells was slightly upregulated in primary prostate cancer patients after definitive RT, but not after salvage RT. CONCLUSION: Definitive and salvage RT exert similar effects on the composition of lymphocyte subpopulations in prostate cancer patients. Total lymphocyte counts are lower in both patient groups compared to healthy controls and further decreased after RT. B cells are more sensitive to definitive and salvage RT than T and NK cells.

Comparative analysis of the effects of radiotherapy versus radiotherapy after adjuvant chemotherapy on the composition of lymphocyte subpopulations in breast cancer patients.

BACKGROUND: Breast cancer is the most common cancer in women worldwide and surgery, radiotherapy (RT) and chemotherapy (ChT) are frequently used to treat this cancer. Adjuvant RT has been shown to cause long-term changes in lymphocyte counts in the peripheral blood. Herein, the time course of changes in lymphocyte subpopulations upon RT was studied in patients with and without adjuvant ChT in order to explore its potential clinical impact. MATERIALS AND METHODS: Total lymphocyte counts and the composition of lymphocyte subpopulations before RT (t0), after 30 Gy (t1), at the end of RT (t2), and 6 weeks (t3), 6 months (t4), and 1 year (t5) after RT were studied by flow cytometry. RESULTS: Absolute lymphocyte counts were significantly lower in all breast cancer patients (n=40) before and also 1 year after RT compared to healthy controls. The percentage of CD3(+)/CD4(+) helper T cells and FoxP3(+) regulatory T cells increased significantly in patients without adjuvant ChT. Different NK cell subpopulations dropped during RT in patients with and without ChT, but recovered to initial levels 6months after RT (t4). During RT (t0-t2) the percentage of CD19(+) B cells significantly dropped in patients without ChT, but gradually increased in patients with adjuvant ChT. Both patient groups reached initial levels 6 months after RT (t4). CONCLUSION: Different lymphocyte subpopulations respond differently to RT with and without adjuvant ChT. CD4(+) T cells increase during RT, whereas NK cells and B cells decrease in patients without ChT, but recover within 6 months after RT. Treg cells gradually increase in patients without ChT from t0 to t5, but not in patients with adjuvant ChT.