8th Baltic Congress of Radiology

Urogenital Radiology

oral abstract

Prostate cancer is the most commonly diagnosed solid tumor for males in all northern and western European countries. External-beam radiotherapy (RT) is most appropriate for men with intermediate-risk or high-risk prostate cancer and is associated with long-term disease control in most patients. Men with localized prostate cancer often are treated with conventionally fractionated external beam RT with 1,8-2 Gy daily fractions over 8 to 9 weeks which is an established treatment modality for men in all disease risk groups. Since development of linear accelerators and new experimental treatment regimen development, hypofractionated RT, which is given over a shorter time with larger doses per fraction than standard RT, can improve the therapeutic ratio and resource use, is more convenient for patients and has less toxicity and complications. Recent trials and studies (CHHiP for intermediate risk patients and HYPRO for high-risk patients) hypothesized that hypofractionation versus conventional fractionation is similar in efficacy without increased toxicity. Due to COVID pandemic, evidence-based reviews consider moderate hypofractionation for localised disease as the new standard of care since patients are in need to finish their treatment sooner and not be at risk for coronavirus while receiving RT in hospital. The aim of this study was to determine the side effects and to compare acute and late treatment-related gastrointestinal and urological toxicity of intensity-modulated hypofractionated RT in treating patients with localized prostate cancer. Main objectives of this research was to determine the safety and efficacy of hypofractionated high-dose intensity-modulated radiotherapy in patients with localized prostate cancer.

Altogether 57 patients were inrolled in the retrospective and descriptive study conducted at Pauls Stradins Clinical University hospital, Radiation therapy department in Riga, Latvia. Data were conducted from November 2019 to January 2022. Patients were stratified in low-risk and high-risk groups using Roach formula to predict the risk of seminal vesicle involvement demonstrating the value of combining the pre-treatment prostate specific antigen (PSA) and Gleason Score and Yale formula which calculates the lymph node involvement risk combining the pre-treatment prostate specific antigen, Gleason Score and Clinical T-stage. Using Yale formula patients were stratified in two groups: low-risk with the calculated probability of lymph node involvement <15% and high-risk (>15%). All patients received radiotheraphy treatment on Elekta Versa HD linac. Radiotherapy treatment plan was made in MONACO planning system. Patients underwent hypofractionated high-dose intensity-modulated radiotherapy (IMRT) with total dose of 60 Gy in 20 fractions every working day over 4 weeks. Patients were planned and treated each day with the use of a bowel and bladder preparation protocol. Treatment was delivered with high-energy linear accelerators with daily image guidance onto the target. Permitted image guidance techniques included implanted fiducial markers and cone beam computed tomography. Gastrointestinal and bladder complications were evaluated using Radiation Therapy Oncology Group (RTOG) late radiation morbidity scoring schema and were compared twice: before starting radiation therapy treatment and after the last radiation therapy procedure. Descriptive data were collected and analyzed using IBM SPSS Statistics program.

The average age of the patients was 73,0 years +/- 7,9 (min=55, max=86). Using clinical TNM classification, 7 (12,2%) patients had T1 cancer, 19 (33,2%) had T2, 29 (51,1%) had T3, but only 2 (3,5%) patients had T4 cancer. All 57 patients (100%) had N0 tumor. Most of the patients (55 (96,4%) had M0 disease, 2 (3,5%) patients had M1. Almost half (28 patients (49,1%) had stage III prostate cancer, 22 (38,7%) patients had stage II, 6 (10,5%) patients had stage I, 1 (1,7%) patient had stage IV disease. The most common tumor grade was Gleason score of 3+4=7 (27 (47,4%) patients), more than forth of the patients (15 patients (26,3%) had Gleason score of 3+3=6. PSA level before the treatment for all patients was in the range from 3,43 ng/ml to 84 ng/ml. Evaluation of the lymph node risk was calculated with Yale formula which classified patients in two groups: low-risk (<15%) and high-risk (>15%). 38 (66,6%) patients were low-risk, 19 (33,4%) patients were high-risk of lymph node involvement. Using Roach formula, the risk for Seminal Vecisle invasion was calculated and it variated from 3% to 86% for all patients included. Evaluating the large intestine toxicity using RTOG scoring schema, for majority (94,7%) of the patients had Grade 0 proctitis, 3 (5,3%) patients had Grade 1 proctitis. After completing hypofractionated RT manifestation of proctitis was re-evaluated and most of the patients (42 patients (73,7%) had Grade 0 proctitis, 13 (22,8%) patients had Grade 1 proctitis, 2 (3,5%) patients had Grade 2 proctitis. Bladder toxicity was also assessed using RTOG scoring schema, before RT 43 (75,4%) patients had Grade 0 cystitis, 12 (21,1%) patients had Grade 1 cystitis, 2 (3,5%) patients had Grade 2 cystitis. Re-evaluating after RT listed that half (52,7%) of patients had Grade 1 cystitis, 11 (19,3%) patients had Grade 2 cystitis, 8 (14,0%) patients had Grade 0 cystitis and 8 (14,0%) patients had Grade 3 cystitis. More than half (54,4%) had other additional diseases.

Post-radiotherapy symptoms relate to treatment methods, total dose, patient factors, and fractionation schedules. The results of this study support the primary hypothesis that a moderately hypofractionated RT regimen of 60 Gy in 20 3-Gy fractions over 4 weeks for localized prostate cancer has minor or no bladder and large intestine complications. After completing RT of 60 Gy in 20 fractions, Grade 1 cystitis was most common complication seen in 30 patients (52,7%). Radiation proctitis was experienced even less commonly since most of the patients (73,7%) finished radiotherapy with Grade 0 proctitis. Hypofractionated RT is more convenient for patients and should be considered as the new standart of care for low and intermediate-risk prostate cancer. Avoidance of excessive toxicity, particularly late bladder and bowel toxicity, is essential for hypofractionated regimens to be adopted into standard practice. The favorable results in the latest studies (CHHiP and HYPRO) reflect the mandated radiotherapy technique using an integrated simultaneous boost with relatively narrow planning target volume margins with daily cone-beam computer tomography verification to provide precise dose delivery and clinical target volume coverage with minimal damage to the surrounding healthy tissue, reducing rectal dose. Therefor no increase is to be seen in toxicity with hypofractionated RT delivered by highly conformal image-guided techniques. Rates of both acute and chronic proctitis have been decreasing with improved radiation therapy techniques that allow for the targeted delivery of higher doses of radiation. It can suggest that hypofractionated radiotherapy is safe and cause less acute and chronic bladder and bowel complications compared to conventional RT. In conclusion, results of this study provide evidence to support the use of moderate hypofractionated RT in patients with intermediate-risk prostate cancer.

External-beam radiotherapy (RT) is most appropriate for men with intermediate or high-risk prostate cancer and often conventional RT is used. Hypofractionated RT allows targeted delivery of higher doses of radiation delivered by highly conformal image-guided techniques and rates of both acute and chronic bladder and bowel complications have been decreasing. It can suggest that hypofractionated RT is safe and should be considered as the new standart of care for localized prostate cancer.

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